Issued August 8, 1911. 
 
 U. S. DEPARTMENT OF AGRICULTURE, 
 
 BUREAU OF ANIMAL INDUSTRY. BULLETIN 142. 
 
 A. D. MELVIN, CHIEF OF BUREAU. 
 
 3OUR1NE OF HORSES 
 
 ITS CAUSE AND SUPPRESSION. 
 
 BY 
 
 JOHN R. MOHLER, V. M. D., 
 
 Chief of the Pathological Division . 
 
 WASHINGTON: 
 
 GOVERNMENT PRINTING OFFICE. 
 1911.
 
 Issued August 8, 1911. 
 
 U. S. DEPARTMENT OF AGRICULTURE, 
 
 BUREAU OF ANIMAL INDUSTRY. BULLETIN 142. 
 A. D. MELVIN, CHIEF OF BUREAU. 
 
 DOURINE OF HORSES: 
 
 ITS CAUSE AND SUPPRESSION. 
 
 BY 
 
 JOHN R. MOHLER, V. M. D., 
 Chief of the Pathological Division 
 
 WASHINGTON: 
 
 GOVERNMENT PRINTING OFFICE. 
 1911.
 
 THE BUREAU OF ANIMAL INDUSTRY. 
 
 Chief: A. D. MELVIN. 
 Assistant Chief: A. M. FARRINGTON. 
 Chief Ckrk: CHARLES C. CARROLL. 
 
 Animal Husbandry Division: GEORGE M. ROMMEL, chief. 
 Biochemic Division: M. DORSET, chief. 
 Dairy Division: B. H. RAWL, chief. 
 
 Inspection Division: RICE P. STEDDOM, chief; R. A. RAMSAY, MORRIS WOODEN, 
 and ALBERT E. BEHNKE, associate chiefs. 
 
 Pathological Division: JOHN R. MOHLER, chief. 4 
 
 Quarantine Division: RICHARD W. HICKMAN, chief. 
 Zoological Division: B. H. RANSOM, chief. 
 Experiment Station: E. C. SCHROEDER, superintendent. 
 Editor: JAMES M. PICKENS.
 
 LETTER OF TRANSMITTAL. 
 
 U. S. DEPARTMENT OF AGRICULTURE, 
 
 BUREAU OF ANIMAL INDUSTRY, 
 
 Washington, D. C., July 5, 1911. 
 
 SIR: I have the honor to transmit herewith and to recommend 
 for publication as a bulletin of this bureau a manuscript entitled 
 "Dourine of Horses: Its Cause and Suppression," by Dr. John R. 
 Mohler, Chief of the Pathological Division. 
 
 Respectfully, A. D. MELVIN, 
 
 Chief of Bureau. 
 Hon. JAMES WILSON. 
 
 Secretary of Agriculture.
 
 CONTENTS. 
 
 Page. 
 
 Introduction : 7 
 
 Nomenclature 8 
 
 History 8 
 
 Definition 10 
 
 Cause 10 
 
 Trypanosoma equiperdum 11 
 
 Cultivation of the trypanosome 13 
 
 Searching for the trypanosomes 15 
 
 Infectiveness 17 
 
 Symptoms 27 
 
 Post-mortem lesions 29 
 
 Course of the disease 31 
 
 Prognosis 31 
 
 Differential diagnosis 32 
 
 Treatment 34 
 
 Method of eradication 35 
 
 5
 
 ILLUSTRATIONS. 
 
 Page. 
 PLATE I. Fig. 1. Trypanosoma equiperdum from plaque on mare 79. Fig. 2. 
 
 Trypanosoma equiperdum from a culture 12 
 
 II. Fig. 1. Percheron stallion 42 showing condition at the time of pur- 
 chase. Fig. 2. Same stallion after dourine had developed 18 
 
 III. Fig. 1. Percheron mare 80 showing chronic dourine. Fig. 2. Mare 
 
 47 in the last stage of dourine 18 
 
 IV. Fig. 1. Mare 80 affected with dourine, showing paralysis of the right 
 
 nostril. Fig. 2. Lesions of dourine involving the external genitals 
 
 and perineum of mare 47 28 
 
 V. Mare 79, bred to an imported stallion March 7, 1911, and developed 
 
 evidences of dourine 15 days later 28 
 
 6
 
 DOURINE OF HORSES: ITS CAUSE AND SUPPRESSION. 
 
 INTRODUCTION. 
 
 On May 27, 1911, the Bureau of Animal Industry received a letter 
 from Dr. J. I. Gibson, State veterinarian of Iowa, stating that there 
 was in Taylor County an outbreak of a disease suspected of being 
 dourine, and requesting that an expert be sent to make an investiga- 
 tion. The disease had been reported by Dr. A. H. Quin, a practitioner 
 of Creston, Iowa, and his diagnosis was subsequently confirmed on 
 the part of the bureau by Drs. A. D. Melvin, E. T. Davison, and the 
 writer, who were of the unanimous opinion that the symptoms and 
 lesions manifested were the most typical of any of the cases they had 
 observed. Three of the affected mares were at once purchased and 
 sent to Washington for experimental purposes. After a careful and 
 prolonged examination of almost 200 slides, six living, wriggling 
 trypanosomes, Trypanosoma equiperdum, were found on June 28, 
 191 1 , by the writer in the blood-tinged serum obtained from a recently 
 developed plaque on the abdomen of one of the mares (No. 79), thus 
 confirming the diagnosis and also establishing the identity of the dis- 
 ease with that of Asia, Africa, and Continental Europe. This is the first 
 discovery of the Trypanosoma equiperdum in the natural cases of dourine 
 in the United States, although in 1903 considerable work was done with 
 this trypanosome imported from France and subsequently inoculated 
 into horses at the Bethesda Experiment Station. Previous to 1911 
 there had been no authentic case of dourine reported among the 
 horses of this country since 1906, although there had been a number 
 of alleged or suspected cases brought to the bureau's attention from 
 time to time which demanded a full investigation, but always with 
 negative results. The object of this paper is therefore not only to 
 describe the methods which have been employed in suppressing this 
 insidious disease of horses but also to furnish such a description of 
 the symptoms and lesions as to make it easier to differentiate dourine 
 from other diseases which may simulate it. The chronicity of the 
 affection, its ultimate fatal results, and the valuable breeding animals 
 which are usually attacked, make it of considerable economic sig- 
 nificance and render its early recognition and the subsequent enforce- 
 ment of prophylactic measures extremely important to the horse 
 breeder and the sanitarian. 
 
 7
 
 8 DOURINE OF HORSES: ITS CAUSE AND SUPPRESSION. 
 
 NOMENCLATURE. 
 
 This disease has been described under various names, according to 
 the country in which it is found, chief among which may be mentioned 
 "el dourine," "maladie du coit," covering disease, equine syphilis, 
 genital glanders, breeding paralysis, chancrous epizootic, epizootic 
 paraplegia, and "beschalkrankheit." The most commonly employed 
 name for this affection in the United States is the short and distinctive 
 term " dourine," which is taken from the Arabic, meaning "unclean." 
 
 HISTORY. 
 
 The primeval home of the malady is supposed to be in Asia, where 
 it is considered to have existed for centuries. It was. first definitely 
 described in 1796 by Ammon as occurring among the animals belong- 
 to the sovereign of Prussia at Trakehnen. During the first half of 
 the nineteenth century it was described as occurring in many coun- 
 tries of Europe, including Germany, France, Austria, and Switzer- 
 land. It was also known to be prevalent along the northern region 
 of Africa in Algiers. It is supposed to have been introduced during 
 the early part of the nineteenth century into Continental Europe 
 through the importation of breeding horses, especially Arab stallions, 
 from the Orient. 
 
 In the United States the disease was first suspected in 1885 and 
 recognized in 1886 by Dr. W. L. Williams, who was then a practi- 
 tioner at Bloomington, 111. The infection was traced to a Percheron 
 stallion, imported from France in 1882, which had a brand mark 
 under the mane very much resembling the letter D (dourine ?). It is 
 supposed that he was affected with the disease and had been branded 
 in France before being transported to this country. The nature of 
 the disease not being at first recognized, its dissemination occurred 
 before attention was attracted to it. The State of Illinois, however, 
 took hold of the outbreak and as a result of rigid prophylactic meas- 
 ures the disease was eradicated from the State in 1888, but not 
 before an affected stallion had been shipped to Gordon, Nebr., 
 thereby starting up a new center of infection in that locality. 
 
 In 1892 dourine was again brought into public notice by the appear- 
 ance of an outbreak among the breeding horses of northwestern 
 Nebraska, the history of which suggested that it originated with this 
 Gordon stallion. An inspector of the Bureau of Animal Industry 
 investigated the outbreak and found that upward of 200 mares and 
 stallions were affected with the disease. Steps for the eradication 
 of this outbreak were begun in June, 1893, at which time some of 
 the diseased animals had died, and the breeders were using all the 
 precautions possible to prevent its spread. Under the authority of 
 the Secretary of Agriculture all diseased animals still alive, including 
 32 in Nebraska and 5 in South Dakota, were purchased and destroyed.
 
 NOMENCLATURE HISTORY. 9 
 
 After an expenditure of about $5,500 the disease was considered to 
 have been eradicated from that section of the country. Five years 
 later the infection again made its appearance in the same portion 
 of Nebraska, and early in 1899 the bureau again began the work of 
 eradication. Many inspections were made and those animals which 
 were found diseased were purchased and killed. Many obstacles 
 were encountered and the disease evidently kept smoldering during 
 1900. 
 
 In 1901 the infection appeared with increased vigor, this time in 
 the Pine Ridge and Rosebud Indian Reservations in South Dakota, 
 in addition to northern Nebraska, and more stringent measures were 
 immediately inaugurated to control the spread of the disease. During 
 the next year 10 diseased stallions and 76 diseased mares were pur- 
 chased and slaughtered and 29 diseased stallions were castrated. 
 However, eradication in this region was extremely difficult, owing to 
 the wild condition of the country as well as of the horses and from 
 the fact that many horse owners would try to conceal from the in- 
 spectors animals which they knew to be affected with the disease. 
 This reappearance of the disease among horses in Nebraska and South 
 Dakota after it apparently had been stamped out caused a thor- 
 ough investigation of its latent qualities and other peculiarities, and 
 as a result Veterinary Inspectors E. T. Davison and W. J. Fretzs 
 were stationed at Rushville, Nebr., with instructions to prosecute 
 vigorously the work of eradication. In 1903 there were 16,287 horses 
 inspected, of which 511 were found diseased and were killed, while 
 1,899 stallions were castrated. Careful and vigorous work was con- 
 tinued in this way, with the result that 8,705 horses were inspected 
 in 1905, but only 1 stallion and 8 mares were found suspicious and 
 destroyed and 9 stallions castrated. 
 
 During the year 1903 dourine was reported in Van Buren County, 
 Iowa, and steps were immediately taken to stamp it out. As a result 
 410 horses were inspected, 2 exposed stallions were castrated, and 18 
 mares slaughtered. No connection could be established between this 
 outbreak and that in Nebraska, but it was quite definitely determined 
 that an imported Percheron stallion purchased by a company of 
 farmers was responsible for its appearance. 
 
 In 1906 the last suspicious cases of dourine 1 stallion and 2 mares 
 were destroyed in South Dakota, and sufficient time has since elapsed 
 to warrant confidence that the disease has been completely eradicated 
 from that section of the United States. 
 
 In Canada the presence of dourine was discovered by Dr. Burnett 
 in 1904, and the causative trypanosome was demonstrated by Dr. 
 Watson in 1907, from the vulva of a mare. From the occurrence of 
 this disease until the latest available published report in 1909, 628 
 animals were purchased and destroyed. A marked diminution in 
 the number of infected animals is apparent in the report, and the dis- 
 ease is said to be under control. 
 834 Bull. 14211 2
 
 10 DOUBINE OF HOESES : ITS CAUSE AND SUPPRESSION. 
 
 As already stated, an outbreak of dourine has recently (June, 1911) 
 been located in Taylor County, Iowa, where 4 stallions have been 
 found affected and 5 exposed to this disease. One of the former 
 stallions has since died of the infection. In addition, 5 mares have 
 shown symptoms of dourine, 1 of which subsequently died of the 
 disease, 9 are suspicious cases, and 94 have been exposed, but at 
 present show no evidence of infection. These diseased animals, to- 
 gether with all exposed stallions and mares, were immediately quaran- 
 tined by the State. Those showing lesions of the disease were pur- 
 chased by the Government and destroyed, while the exposed animals 
 are still in quarantine under observation. Several Federal and State 
 inspectors are making farm-to-farm inspections with the view of dis- 
 covering any latent or hidden cases, and it is now believed that the 
 infection is entirely under control. The source from which this center 
 of infection was derived is only a matter of conjecture, but there is 
 apparently no connection between this and any of the previous out- 
 breaks. No authentic information as to the origin of the outbreak 
 has been discovered up to the present time, but all cases lead back to 
 a Percheron stallion, which was imported in 1909 and brought direct to 
 Lenox, Iowa. The possibility of such animals bringing the infection 
 into this country must be apparent from the following explanation. 
 
 Schneider and Buffard maintain that in France dourine appears 
 nearly every year in the Department of Basses-Pyrenees on the 
 Spanish frontier. It is stated that mares get infected by the asses or 
 horses by which they are covered. It is the custom to have a mare 
 first covered by an ass, and if not impregnated she is then served by 
 a stallion. The asses operate on both sides of the frontier, and in 
 this way introduce the disease into France from Spain, where it has 
 been known to occur for years, especially in Navarre. 
 
 DEFINITION. 
 
 Dourine is a specific infectious disease affecting under natural con- 
 ditions only the horse and the ass, transmitted from animal to animal 
 by the act of copulation, and due to a single-celled animal parasite or 
 protozoan, the Trypanosonui equiperdum. It is characterized by an 
 irregular incubation period, the confinement of the first symptoms 
 to the genital tract, the chronic course which it runs, and by finally 
 producing complete paralysis of the posterior extremities, with a fatal 
 termination in from six months to two years. 
 
 CAUSE. 
 
 Many widely different theories as to the exact cause of this affection 
 have existed and been advocated in the past 50 years. The fact that 
 the disease spread from animal to animal in certain centers of infec- 
 tion, and that large horse-breeding districts and countries which did
 
 CAUSE. 11 
 
 not import any breeding animals, such as New Zealand, Australia, 
 England, and South America, remained free from the disease, showed 
 it to be of an infectious nature. Investigations by Thanhoffer 
 resulted in his obtaining bacilli, cocci, and streptococci from the 
 blood and nervous system of animals dead of this disease. However, 
 none of these organisms were invariably present, and from the fact 
 that the disease was confined almost exclusively to breeding animals 
 and seemed to be transmitted solely through the act of copulation 
 doubt arose as to the likelihood of any vegetable organisms being the 
 causal agent in its production and dissemination. At one time it was 
 considered to be identical with human syphilis and was thought to 
 be conveyed from man to asses and mares, but the fallacy of this belief 
 was demonstrated by Haussman and Knauert. 
 
 As opposed to the theory of coition playing the entire part as a 
 means of transmission of the disease, we have the statements of 
 Hayne and Haxthusen, who have reported the disease in geldings 
 and also in mares which have never had sexual intercourse with the 
 stallion. It may be also transmitted with ease artificially by means 
 of inoculation into horses, dogs, rabbits, rats, and other susceptible 
 animals, with relatively large quantities of the blood and membranes 
 of certain organs of animals affected with the disease. However, 
 sexual intercoufse is by far the most common means of transmission, 
 and if other means do exist they are so rare that they have little or 
 no practical importance in the adoption of measures for the suppres- 
 sion of the disease. 
 
 It was not until 1896 that the true cause of the malady was dis- 
 covered by Rouget, but his work was neither credited nor confirmed 
 until 1899. At this time two French army officers, Schneider and 
 Buffard, proved that trypanosomes were associated in causal relation 
 to the disease, by successful inoculations of animals with organisms 
 from an infected stallion. Later Nocard verified these results, and 
 subsequently, in 1901, Laveran and Mesnil carefully described the 
 trypanosome, naming it Trypanosoma rougeti after its discoverer, 
 although it had previously been named by Doflein, Trypanosoma 
 equiperdum. 
 
 TRYPANOSOMA EQUIPERDUM. 
 
 This trypanosome is a unicellular animal parasite (flagellate) very 
 closely resembling the numerous other varieties of trypanosomes 
 which have during the last few years been proved to be the causes 
 of several tropical diseases of animals, chief of which may be men- 
 tioned surra, nagana, and mal de caderas. When taken from the 
 blood of an infected animal it is a somewhat spindle-shaped organism 
 with the posterior extremity bluntly conical ; anteriorly (the head) it 
 is prolonged into a long, wavy, whiplike flagellum, giving the appear-
 
 12 DOUBINE OF HOUSES: ITS CAUSE AND SUPPRESSION. 
 
 ance of a tail, thus apparently reversing the true position of the tail 
 and head. (See PI. I, fig. 1.) Along one side is a wavy, undulating, 
 flangelike membrane terminating in the flagellum. The nucleus is 
 large and located centrally, while the centrosome or kinetonucleus is 
 situated posteriorly, and is the starting point of the undulating 
 membrane and flagellum. The trypanosome is actively motile, but 
 not so much so as certain other forms found in rats. Motion may 
 occur indiscriminately forward or backward by the rapid lashing 
 movements started in the flagellum and continued in the vibratory 
 movements of the undulating membrane; also by the contraction 
 of the protoplasm of the body. The size varies from 25 to 30 microns 
 in length by about 2 microns thick. 
 
 The most satisfactory way of determining the presence of these 
 parasites is to examine fresh preparations of the suspected fluid 
 spread in a thin layer on a slide, covered with a cover slip and viewed 
 with a 4-millimeter objective and No. 4 ocular. The trypanosomes 
 may be readily stained and their structure brought out well by 
 Giemsa's azur-eosin stain, Nocht's modification of Romanowsky's 
 method, or by BorreFs blue. 
 
 In order to make a complete study of this protozoan as it exists 
 in France and Algiers, a small dog was imported by the writer for 
 the bureau in 1903 after being inoculated in Prof.. Nocard's labo- 
 ratory at the Alfort Veterinary School with blood infected with 
 Trypanosoma equiperdum. This animal arrived safely in this country 
 in an apparently healthy condition, giving rise to apprehensions as 
 to the success of the inoculation. In a few weeks, however, it began 
 to show signs of illness. The temperature rose to 103 F.; the 
 sheath and the inside of the thigh became swollen and edematous. 
 These swellings at first would disappear for a day or two, only to 
 recur over a larger area. The animal became considerably emaciated, 
 the edematous swellings spread, involving the whole inner surface of 
 the thighs, as well as the entire length of the sheath, the appetite 
 became poor, and the animal died in November, about 6 weeks after 
 its arrival or 8 weeks after the inoculation. During the life of the 
 dog after the first appearance of symptoms microscopic examinations 
 were made daily of the blood taken from the peripheral circulation 
 as well as from the serum in the edematous areas about the genitals 
 for the purpose of recording the trypanosomes present, but they 
 were always extremely scarce. After death these organisms were 
 found in great numbers in the heart, blood, lungs, liver, kidneys, 
 and spleen. 
 
 It was with the trypanosomes obtained from this dog, kept alive 
 by continued passage through white rats, rabbits, dogs, and horses, 
 that most of our work with the organism has been done. White 
 rats were by far the most satisfactory experiment animals for the
 
 Bui. 142, Bureau of Animal Industry, U. S. Dept. of Agriculture. 
 
 PLATE I. 
 
 FIG. 1 . TRYPANOSOMA EQUIPERDUM FROM PLAQUE ON MARE 79. (COMPOSITE DRAWING.) 
 
 Haines, del. 
 
 FIG. 2. TRYPANOSOMA EQUIPERDUM FROM A CULTURE.
 
 CAUSE. 13 
 
 propagation of the organism, as it proved much more pathogenic 
 for them, death usually occurring in from 2 to 6 months after 
 inoculation. The trypanosomes were also more readily recovered 
 from these animals. Although rabbits after inoculation became grad- 
 ually emaciated and finally died in from 2 to 8 months, it was only 
 by long and careful microscopic examination that any trypanosomes 
 could be found in their viscera after death. 
 
 The length of time which this protozoan lives when kept in blood 
 or body fluids taken from the dead annuals varies considerably, but 
 is generally stated as being a very short tune. Thus Rouget observed 
 it to keep its motility for 18 hours, but never after 24 hours. In the 
 blood of the French dog, as well as in physiologic salt solution emul- 
 sions of the liver and spleen, the parasites were actively motile on 
 the second day, a few were still observed on the third day, but on 
 the fourth day none could be found, showing that all were destroved 
 
 between 72 and 96 hours after the death of the host. 
 
 i 
 
 CULTIVATION OF THE TRYPANOSOME. 
 
 The attempts at cultivation of this organism were attended with 
 a great many difficulties, as it was rarely possible to obtain the 
 organisms in sufficient concentration to get more than a few try- 
 panosomes in each tube of media. Contaminations were also fre- 
 quent, as hanging drop preparations made under perfectly sterile 
 precautions from the blood and organs of the rats showed bacteria 
 in numerous cases within one-half hour after death. The media also 
 had to be made up fresh continually, as the water of condensation 
 dried out and the color of the blood in the media rapidly became 
 dark, due to the breaking up of the hemoglobin, after which change 
 the material was of little value for the growth of the parasite. The 
 medium used in these experiments was blood agar prepared after the 
 method suggested and used by Novy and McNeal. 
 
 Rabbits' blood was used throughout the experiments. The blood 
 was drawn from the carotid artery through a sterilized glass tube 
 into sterile potato tubes containing sterile beaters with which the 
 blood was defibrinated. More satisfactory results were afterwards 
 obtained with less danger of contamination by securing all the blood 
 in one flask. The sterile defibrinated blood was then mixed with 
 equal parts of melted neutral or faintly alkaline agar, or in the pro- 
 portions of 2 parts of blood or, better, 3 parts to 1 of agar, and 
 allowed to solidify in the slanting position, after which the conden- 
 sation water was inoculated. Great care had to be taken in keeping 
 the constituents of the medium sterile during all the manipulations, 
 as the sterilization of the finished product was impracticable, owing 
 to the firm coagulation and alteration of the blood by the heat.
 
 14 DOURINE OF HORSES: ITS CAUSE AND SUPPRESSION. 
 
 Rouget attempted to cultivate the Trypanosoma equiperdum at 
 37 C., but was uniformly unsuccessful, the organism never multiply- 
 ing and only remaining alive for 24 hours. The same results attended 
 all our early efforts, although the cultures were invariably kept at 
 room temperature. The organism, however, seemed to flourish in 
 white rats, and, if anything, it became more virulent for them by 
 successive inoculations, appearing in greater and greater numbers in 
 the blood and viscera at post-mortem until finally hanging-drop 
 preparations made from the blood seemed to be alive with the minute 
 wriggling organisms. One loopful of this blood would contain prob- 
 ably 200 or even more of these trypanosomes. The continued 
 inoculation of a medium composed of three parts of blood to one of 
 agar with such great numbers of the organism was finally crowned 
 with success, since which time 14 generations have been grown, cov- 
 ering a period of over nine months, and no difficulty was experienced 
 in keeping the trypanosomes alive by frequently transferring them 
 to fresh medium. The cultures were finally destroyed through con- 
 tamination of the media. The inoculation of experiment animals 
 with these cultures seems to indicate that there was some reduction 
 in their virulence, but too small a number of inoculations have been 
 made to draw definite conclusions. 
 
 The first three attempts at cultivating this protozoan were direct 
 failures, as the 6 tubes used in the first two cases and 9 in the 
 third failed to show any trypanosomes after the fourth day. The 
 fourth inoculation, consisting of 11 tubes made on March 9 with 
 blood agar (3 to 1) resulted in the multiplication and development in 
 one tube of trypanosomes, but after the sixteenth day this encourag- 
 ing culture died, and despite subinoculations no further growth could 
 be obtained. On April 12 a fifth attempt was entirely successful, as 
 3 of the 14 tubes inoculated gave evidence of development. After 
 the inoculation of the medium with the infected blood the tubes 
 were sealed with paraffin or sealing wax and placed in a dark closet 
 at room temperature. Six days later a drop of the water of conden- 
 sation was examined and found to contain a number of very active 
 trypanosomes, some that were languid, showing a tendency to agglom- 
 erate, and also many degenerated and inactive organisms. On each 
 succeeding day the number of the latter seemed to be augmented, 
 while the very active forms were rapidly decreasing, until the twelfth 
 day, when the tubes showed numerous irregular granular bodies 
 which were small, contracted, and rounded, representing degenerated 
 forms of the trypanosome. Two days later small forms, about one- 
 half the size of the adult organism, were observed gathered together 
 in colonies containing from 4 or 5 to 20 or 30 individuals. These 
 were actively motile, and by their appearance suggested a new 
 generation of parasites. The smaller colonies were in several cases
 
 CAUSE. 15 
 
 attached to a red blood corpuscle. No undulating membrane could 
 be detected on the bodies of the parasites, and it was very difficult to 
 determine whether these bodies were gathered together with their 
 anterior or posterior extremity directed inward ; in some cases, how- 
 ever, very fine filaments could be seen in the center of the colonies 
 or rosettes. 
 
 These colonies increase in number and size until one clump, by the 
 coalescence of numerous smaller groups, may contain several hun- 
 dred closely packed wriggling forms of trypanosomes. The elements 
 in these united clumps are arranged radially like the clusters of 
 actinomyces. (See PI. I, fig. 2.) Such large colonies are not fre- 
 quent and are always irregular, and usually elongate in outline. As 
 they grow older some of the individuals become disengaged and 
 wriggle around, frequently throwing their flagella about a red cell, 
 and move about in a circle, but with less activity than is shown by 
 the original organisms. The flagella appear usually longer than the 
 length of the trypanosome's body. At times individuals are seen 
 united in pairs by their posterior extremities. Many involution 
 forms and bodies representing developmental stages may also be 
 observed with an irregular nucleus, one or several vacuoles in the 
 posterior extremity, and several small granular bodies at the anterior 
 extremity. These organisms are of various shapes, from long, narrow, 
 crescentic forms to short, thick bodies like tadpoles. Some of these 
 organisms are inactive and are probably involution or transitional 
 forms, while others are quite motile and represent the developmental 
 stages. The nuclei of the former seem to be the first to alter their 
 shape, assuming various peculiar positions and finally disappearing. 
 The cell body then contains a number of small vacuoles scattered 
 irregularly throughout its protoplasm. The protoplasm finally con- 
 tracts into a spherical body or may disappear entirely, leaving the 
 centrosome attached to the flagella and giving the appearance of a 
 spermatozoan. 
 
 The growth of these protozoa in the blood-agar medium gave but 
 slight microscopic evidence of development. No colonies appeared 
 on the slanted surface of the medium, and the only indications 
 denoting growth were a slightly increased turbidity of the water of 
 condensation and a flocculent precipitate at the bottom which con- 
 tained many bodies. 
 
 SEARCHING FOR THE TRYPANOSOMES. 
 
 After the trypanosome had been obtained and studied a mare 
 and a Percheron stallion affected with the American form of the 
 disease were shipped to Washington from the West in 1904. These 
 animals, particularly the stallion, exhibited all the characteristic 
 symptoms of the disease and were considered typical cases in which
 
 16 DOURINE OP HORSES: ITS CAUSE AND SUPPRESSION. 
 
 to find the trypanosomes. Blood was drawn from the animals two 
 and three times weekly from both the veins and from plaques or 
 urticarial swellings which appeared frequently on the stallion. On 
 several occasions blood was drawn at midnight in order to insure 
 the detection of the parasites in case they were only present in the 
 circulation nocturnally. Without exception, however, no trypa- 
 nosomes were found, and post-mortem examinations held on these 
 animals were negative for these parasites in every case. Further, 
 numerous experimental animals, including rabbits, guinea pigs, rats, 
 mice, and dogs, were inoculated with small quantities of blood and 
 various other fluids from the diseased horses, with negative results 
 and although in some cases death of the small experimental animals 
 seemed to result from inoculation after a progressive emaciation 
 lasting over a period of three to five months, the majority of these 
 animals died of some intercurrent disease without showing any 
 trypanosomes. From the fact that the trypanosome was found 
 rather easily in the animals dead of the European disease, with the 
 exception of rabbits, and that the most careful examination, micro- 
 scopical as well as inoculation tests failed to show the parasite in 
 the natural disease of this country until the 1911 outbreak of dourine 
 in Iowa, it seems conclusive to the writer that the Trypanosoma 
 equiperdum are fewer in number, less aggressive, and not as virulent 
 in the dourine of the United States as they are in the countries where 
 the disease is indigenous. In fact, the disease appears to be more 
 acute and fatal in Asia and northern Africa than in Europe, and the 
 Trypanosoma equiperdum at the same time are more easily detected, 
 while in America the disease is even less acute and fatal than in 
 Europe and the trypanosome even more elusive. 
 
 The technique used in finding the trypanosomes in the recent Iowa 
 outbreak was to select a freshly formed plaque, from which the hair 
 was shaved and the skin disinfected with carbolic acid followed by 
 alcohol and distilled water. The skin over the plaque was next 
 scarified with a sharp scalpel, as in human vaccination, until the 
 serum commenced to ooze from the capillaries. A water-vacuum 
 apparatus was then prepared in order to aspirate the serum from 
 the plaque. An ordinary strong wash bottle was obtained, in the 
 neck of which was placed a rubber cork with two openings contain- 
 ing a short and a long glass tube. The long tube was connected by 
 rubber tubing to a funnel, which was held against the plaque, while 
 the short tube was connected with a water-exhaust pump. A small 
 cotton plug was left in the short tube of the wash bottle to prevent 
 the return of unfiltered air when the exhaust apparatus was removed. 
 The water was then turned on and the aspirating faucet slowly set 
 to work in order that the exhaust would not be too great at the begin- 
 ning. By this method the blood-tinged serum was readily drawn
 
 INFECTIVENESS. 17 
 
 into the bottle and about 10 c. c. collected. This was subsequently 
 centrifugalized and the upper layer of sediment examined in fresh 
 smear preparations, with the result that trypanosomes were observed 
 in limited numbers. They have always been very scanty and are 
 only found after prolonged and tedious examination. Horse-meat 
 bouillon, rabbits, and rats have been inoculated with the lower 
 strata of this fluid, but thus far only the latter have revealed the 
 presence of these protozoa. 
 
 INFECTIVENESS. 
 
 Material taken directly from infected horses seems to possess a very 
 fluctuating virulence for small experimental animals. While in Alge- 
 ria rabbits and dogs, as well as mice and rats, could be successfully 
 infected, in Hungary the material from horses affected with dourine 
 has only proved to be virulent for solipeds. Thus, as Marek has 
 already pointed out, it seems that the virus has much more viru- 
 lence in the southern than in the northern countries, or that it 
 requires the injection of a large amount of fluid, which small experi- 
 ment animals, as a rule, do not receive, in order to include a sufficient 
 number of trypanosomes to produce the disease. 
 
 The fact that under natural conditions dourine is transmitted 
 solely by coition causes it to differ from all other trypanosomiases, 
 since the latter, so far as is known, are propagated by a biting insect, 
 usually a fly, acting as a vector or carrier. Thus the trypanosome 
 of dourine has the ability to penetrate the intact mucosa of the geni- 
 tal tract, whereby it reaches the blood, and, later, the more distant 
 parts of the body. It takes its nourishment by osmosis and does not 
 invade the blood cells. Its pathogenic action seems to result from 
 the production of certain not yet determined poisons, which act first 
 on the peripheral nerves and later on the general nervous system. 
 A cellular infiltration of the nerve tissues develops, wherefrom the 
 nerve fibers as well as the nerve cells degenerate and finally com- 
 pletely disappear. 
 
 Some authors are of the opinion that the disease has a more rapid 
 and unfavorable course in stallions than in mares, while in asses the 
 disease in most cases is confined to the local infection of the genital 
 organs. Although the predisposition of solipeds to the infection is 
 quite marked, not all stallions which serve diseased mares or all 
 mares served by infected stallions contract the disease. According 
 to Roll, about 66 per cent of the mares exposed to the infection 
 become diseased. 
 
 A striking illustration of how a stallion may transmit the disease 
 from an infected to a healthy mare without contracting the disease 
 himself is given in the case of stallion 31. Frequent attempts were 
 834 Bull. 14211 3
 
 18 DOURINE OF HORSES: ITS CAUSE AND SUPPRESSION. 
 
 made to infect this horse through service with mare 30, affected with 
 dourine, but without results. Finally, on June 4, 1902, the horse 
 was allowed to serve a native Virginia mare (No. 32) shortly after 
 coition with mare 30. This was repeated during the next five days. 
 On June 20 the mucosa of the vulva of mare 32 was erythematous, 
 and rabbits and guinea pigs were inoculated with the secretion with- 
 out results. On June 29, when the mare was taken out of the stable 
 for another service, her gait was noticed to be unsteady behind. 
 She seemed to have a rolling motion from side to side, and it was 
 thought that she would not have sufficient strength to support the 
 male on her back. During the next few days she seemed nervous 
 and to be falling off in flesh, although her appetite remained good. 
 On July 5 the mare became acutely ill about 4 a. m. At 9 a. m. 
 she went down on her side with head thrown back and back curved 
 downward. She was completely paralyzed, being unable to regain 
 her feet even with assistance. Her respiration was quite rapid, both 
 abdominal and thoracic. Her abdomen was somewhat distended 
 with gas and she passed a little gas constantly. Her eyes had a 
 sunken appearance, but there was no perspiration apparent. There 
 was a slight discharge from the vulva, the mucosa of which was 
 extremely inflamed. The mare died at 6 p. m., and an autopsy was 
 made the following morning. 
 
 The autopsy showed the heart to be normal, lungs congested, liver 
 pale, yellow, and friable, kidneys slightly pale, spleen normal in size, 
 with a few ecchymoses under the capsule. The posterior portion of 
 the diaphragm was covered with fine white bands of fibrous tissue. 
 The intestines were filled with gas, but otherwise empty. Small dif- 
 fused extravasations of blood were noted under the serous membrane 
 of the cecum and the large colon. The right ovary was enlarged, and 
 softened with cysts. The left ovary appeared normal in size, but 
 contained small cysts. The mucous membrane of the uterus was 
 edematous and hemorrhagic in patches. The os was inflamed and 
 the vagina contained edematous and hemorrhagic areas. The 
 vulva was inflamed and contained one mucoid cyst and numerous 
 petechial hemorrhages. The bladder showed cystitis and was lined 
 with a yellowish exudate. 
 
 What effect the complicating attack of flatulent colic had upon the 
 course of the disease is difficult to determine, but it is the only case 
 in our experience of such short duration and with such acute lesions 
 of the genitals. Inoculations of material from this mare into rabbits, 
 guinea pigs, rats, and a dog were attended with negative results. 
 
 In order to compare the results obtained from the inoculation of 
 material from a case of natural dourine with the disease produced 
 by the injection of virulent material from France, the following exper- 
 imental cases in equines are appended. These cases have brought
 
 BUL. 142, BUREAU OF ANIMAL INDUSTRY, U. S. DEPT. OF AGRICULTURE. 
 
 PLATE II. 
 
 FIG. 1. PERCHERON STALLION 42, SHOWING CONDITION AT THE TIME OF PURCHASE. 
 
 FIQ. 2. SAME STALLION AFTER DOURINE HAD DEVELOPED. 
 Spots on side and croup give location of plaques.
 
 But. 142, BUREAU OF ANIMAL INDUSTRY, U. S. DEPT. OF AGRICULTURE. 
 
 PLATE III. 
 
 FIG. 1. PERCHERON MARE 80, SHOWING CHRONIC DOURINE. 
 
 Observe the " tucked up" abdomen and emaciation having lost over 700 pounds in the previous 
 
 four months. 
 
 FIG. 2. MARE 47 IN THE LAST STAGE OF DOURINE. 
 Notice the position of the off hind foot and the straightened hock joints.
 
 INFECTIVENESS. 19 
 
 forward some interesting facts about the transmission of the disease, 
 and may be divided into two series : 
 
 1. A case in which the American disease was transmitted by a 
 stallion indirectly from an infected to a normal mare, which has been 
 described above under the notes on mare 32. 
 
 2. Cases in which both the American and the European disease 
 were transmitted by subcutaneous inoculations of infected blood. 
 
 In conducting the latter experiments a female ass was injected 
 with serum taken from plaques which appeared intermittently on 
 stallion 42. Before describing the results of these injections brief 
 notes will be given of the symptoms and lesions manifested in this 
 stallion. 
 
 STALLION No. 42. 
 
 
 
 Black stallion received April 25, 3904, showing chronic symptoms of dourine. 
 This case was one of the most typical that had come under our observation, and one 
 of the few cases in which cutaneous plaques had been noted up to that time. His 
 condition was very poor and showed considerable loss of coordination in the hind 
 quarters. Several deep scars were noted on the penis, and the testicles were swollen. 
 Plates II and III will give a good idea of his appearance before and after showing 
 symptoms of dourine. 
 
 April 26. Stallion served mare 43 after she had been served by stallion 31. 
 
 May 2. Stallion served mare 43. A new plaque has appeared on left shoulder. 
 
 May 11. The plaque developing on left shoulder is now well developed, about 3 
 inches in diameter by one-eighth to one-fourth inch in height, and has a well-defined 
 border. 
 
 An incision was made into plaque and blood drawn to inject rats and rabbits. Fre- 
 quent inoculations of small animals were made with the contents of the plaques, but 
 always with negative results. 
 
 May 12. The plaque noted yesterday seems to be slightly decreased. A new one 
 about 1^ inches in diameter is forming back of right shoulder. 
 
 May 13. Stallion is losing in condition and is very hollow in flanks. The plaque 
 on left shoulder is still present but is reduced in height. Three plaques are present on 
 back of right shoulder. One plaque is forming in front of right shoulder. 
 
 May 14. The plaques are disappearing. 
 
 May 17. Stallion served mare 43 and then mare 36. 
 
 May 19. Has two small plaques on right side and one on left shoulder. The one 
 in front of right shoulder is disappearing. 
 
 May 20. Served mares 43 and 36 in the same manner as on May 17. Has two small 
 plaques back of left shoulder and two small ones on right side. The one in front of 
 right shoulder from which blood was drawn has disappeared. 
 
 May 21. Has five small plaques on right side, one back of right shoulder, one back 
 of and one on left shoulder; the latter is very small. 
 
 May 23. Has two plaques, one about 3 inches in diameter, and the other about 2 
 inches in diameter, back of left shoulder, and one plaque about 3 inches in diameter 
 on right side. 
 
 May 24. Has one plaque about 4 by 5 inches in diameter on left shoulder and one 
 about 6 inches in diameter just in front of left flank. 
 
 May 26. Plaques have nearly disappeared. Animal is extremely thin. An 
 attempt was made yesterday to have him serve mare 41, but he was unable to have an 
 erection.
 
 20 DOURINE OF HORSES: ITS CAUSE AND SUPPRESSION. 
 
 May 27. The plaques have about disappeared. 
 
 May 28. No plaques visible. Hind legs from hocks down are swollen. An attempt 
 was again made to have him serve mare 41, but he was unable. 
 
 May 31. Has two small plaques on left hip. The hocks and below hocks are much 
 swollen. 
 
 June 1. Stallion served healthy mare 41 to-day. 
 
 June 2. Haa one plaque 4 inches in diameter on left hip, and one about 3 by 4 
 inches in diameter on right side. Legs from hocks down are still swollen. 
 
 June 3. Plaques same as yesterday, and hocks are much swollen. 
 
 June 4. The plaques are disappearing. 
 
 June 6. The two plaques noted on left hip several days ago have not yet entirely 
 disappeared. No new ones present. 
 
 June 9. Plaque on left hip from which blood was last drawn is still present. The 
 new one near root of tall has almost disappeared. No new ones. 
 
 June 10. Has two small plaques on back to the right of the spinal column. 
 
 June 11. The plaque from which blood was last drawn has disappeared. The two 
 plaques "noted yesterday are still present. 
 
 June 15. The two plaques noted on side are slowly increasing in size and height. 
 A new one is beginning to develop on opposite side. 
 
 June 17. Plaques still present. Swollen condition of hocks has disappeared. 
 
 June 18. Has one plaque 2 by 4 inches in size on right flank, one about 2 inches in 
 diameter on back to the right of spinal column, and one on left side. 
 
 June 20. Plaques same as noted yesterday, except that a new one about 1 inches 
 in diameter has formed on left shoulder. 
 
 June 22. The plaque on left shoulder is a little larger than on yesterday. One 
 still present on left side. None present on right side. 
 
 June 24. Has three plaques on left side of back. Sheath somewhat swollen. 
 
 June 28. Has an edematous area 4 by 8 by 2 inches in size on chest to left of ster- 
 num. One plaque 2 inches in diameter in left axilla, one the same size in front of 
 left shoulder (the hair has been rubbed from the surface of this one), one 1 inches 
 in diameter on left flank, one about 5 inches in diameter on left hip, and two small 
 ones back of right shoulder. 
 
 June 29. Seems about the same as yesterday. An attempt was made to have this 
 stallion serve mare 43, but while he had no trouble to have an erection he made no 
 attempt to mount the mare, though she seemed very anxious to have him do so. 
 
 July 2. Has had a raw sore 1 inches in diameter on right flank, which looks as 
 though it might have been caused by rubbing. Has two small plaques on the chest 
 to left of sternum. No other plaques visible. Appetite is good and he is in about 
 the same condition as for some time past. 
 
 July 6. Has one plaque about 4 inches in diameter on left hip; three very low 
 ones, each about 1 inches in diameter, in front of left shoulder; one about 3 inches 
 in diameter back of right shoulder. Animal seems to be holding his own. 
 
 July 11. Has one plaque about 4 inches in diameter back of left shoulder and 
 one about 2 inches in diameter on left hip. The sore on right flank, noted some 
 time ago, does not heal and now has an unhealthy appearance. 
 
 July 16. No plaques visible. Sore on right flank healing. Condition of animal 
 is poor, but he seems to be holding his own. 
 
 July 23. Losing in condition. Has one plaque about 2 inches in diameter on 
 left hip. 
 
 July 27. Has a plaque about 3 by 4 inches in diameter on right hip at root of tail; 
 this was noticed for the first time yesterday afternoon. The one noted on left hip 
 some time ago is still present and is about 4 inches in diameter. 
 
 August 3. Plaque on left hip still present; shape and size changes from day to 
 day. The one on right hip from which blood was drawn has disappeared.
 
 INFECTIVENESS. 21 
 
 August 9. Plaque on left hip still present. No new ones. Condition of animal is 
 very poor, but he has a good appetite and is bright. 
 
 September 10. One plaque has appeared on left lumbar region. 
 
 September 20. Donkey 34 injected subcutaneously in left side of neck with 10 c. c. 
 of blood drawn from a plaque on left hip. 
 
 (NOTE. This donkey is to be injected whenever suitable plaques appear on 
 stallion.) 
 
 Stallion has three plaques on each hip, each in size from 2 to 3 inches. 
 
 September 30. Hind legs much swollen, also scrotum and sheath. Several plaques 
 on thighs. 
 
 October 3. Plaques have almost disappeared. General condition very poor. 
 
 October 5. Has been down since yesterday morning, and is helpless. Respiration 
 very much accelerated. 
 
 Forty cubic centimeters of blood drawn and used to inject donkey 34. 
 
 October 6. Still lies stretched out, and respiration is quite rapid. 
 
 October 7. Found dead this morning. 
 
 The temperature of this animal taken twice daily since April 26 shows a range 
 between 101 and 102.8 F. Many microscopic examinations of the contents of the 
 plaques failed to reveal any trypanosomes. 
 
 The post-mortem examination showed that the carcass was very 
 emaciated and anemic, and would probably weigh not more than 
 1,100 pounds. Several small bed sores were observed, involving the 
 skin and underlying tissues in the region of the pelvic prominences 
 and the elbow joint. On skinning, the hide seemed dry and tough, 
 and in the region of the gluteal muscles of the right side three yellow- 
 ish gelatinous areas with injected blood vessels were seen, about the 
 size of a quarter, which represented the location of the last observed 
 plaques. On the dependent (left) side of the carcass the subcutaneous 
 tissues were infiltrated with a thick layer of coagulated serum that 
 had exuded from the blood vessels. The great dorsal muscles on 
 both sides of the spine in the lumbar region were softened, swollen, 
 and contained numerous small hemorrhagic areas. On opening the 
 thoracic cavity both lungs were found to be edematous, while the 
 left was also engorged with blood as a result of hypostatic congestion. 
 The heart was normal and contained black, feebly coagulated blood. 
 The liver appeared normal with the exception of several small 
 yellowish areas of necrosis, probably of parasitic origin. The spleen 
 was slightly shrunken and showed numerous pin-point hemorrhages 
 under the capsule. The right kidney was apparently without lesions, 
 while the left organ was hypostatically injected. The stomach 
 contained a small number of bots, while the large intestine showed 
 several small hemorrhagic points, the result of the 40 or 50 scleros- 
 tomes which it harbored. The spinal cord in the lumbar region 
 contained many petechial hemorrhages, while the meninges were 
 slightly inflamed. There was also an excess of serous fluid in the 
 spinal canal. The penis showed many depigmented areas of irregular 
 shapes and sizes, but at least two of these patches were raised, hard, 
 and dense, resembling cicatricial tissue. The urethra was normal.
 
 22 DOURINE OF HORSES: ITS CAUSE AND SUPPRESSION. 
 
 The testicles were atrophied somewhat and slightly denser in con- 
 sistency than normal. The tunica vaginalis of both testicles showed 
 17 hemorrhagic patches of projecting villi and 2 or 3 warty neoplasms 
 were present on the tunica propria. At the apex of the testicular sac 
 on the right side a large diffused hemorrhagic patch was observed r 
 with several fibrous bands adhering to the testicle. This sac also 
 contflined an excess of yellowish transparent fluid exudate. 
 
 It is interesting to note in connection with this case that although 
 neither of the healthy mares which were served by this stallion con- 
 tracted dourine, and the injection of numerous dogs, rats, rabbits, and 
 guinea pigs resulted negatively, nevertheless serum taken from the 
 plaques and blood from the jugular when injected subcutaneously into 
 donkey 34 produced the disease, but did not show any trypanosomes. 
 The notes on this donkey follow. 
 
 DONKEY No. 34. 
 
 September 20, 1904. Injected subcutaneously in left side of neck with 10 c. c. of 
 blood drawn from a plaque on left hip of stallion 42. 
 
 October 5. Injected subcutaneously in front of left shoulder with 60 c. c. of whole 
 blood drawn to-day from jugular of stallion 42. 
 
 October 7. A firm swelling 10 inches in diameter by 3 inches high is noticed at 
 seat of injection. 
 
 October 18. No abscess has formed at seat of injection, but there is still present a 
 very firm enlargement about 3 by 3 by 1 inches in size. 
 
 November 19. Vulva somewhat swollen. Mucosa of vagina reddened. Animal 
 has a patch of edema about 6 inches in diameter by 1 inch high on abdomen. The 
 skin over an area 4 inches in diameter at seat of injection is indurated. These symp- 
 toms were first observed November 16. 
 
 November 28. Vulva still swollen; vagina congested. Edema on abdomen has 
 almost disappeared. A hard spherical nodule about 1J inches in diameter is seen 
 about 6 inches below seat of injection. This is firmly adherent to the deeper struc- 
 tures but not to the skin. 
 
 December 2. Swelling of vulva is increasing slowly. 
 
 December 6. Vulva still swollen and vagina congested. Many small eruptions 
 on shoulders and withers, which cause the hair to fall out in patches. 
 
 December 10. A patch of edema about 6 by 14 by 1 inches in size over sternum 
 and abdomen; loose tissue in left flank edematous, and left inguinal lymph gland 
 somewhat enlarged. Vulva is still swollen. The eruptions on sternum same as on 
 withers. Nodule in front of left shoulder same as last noted. 
 
 December 12. Edema on flank is slightly reduced; that on abdomen same as last 
 noted. Vulva still swollen. Mammae slightly edematous. Eruptions on skin still 
 present. 
 
 December 20. Vulva much swollen. Eruptions on skin increasing. 
 
 December 29. Animal has a large patch of edema about 1 inch in height extending 
 over ventral aspect of body. Vulva still swollen. 
 
 January 7, 1905. Edema over ventral aspect of body. Vulva much swollen. 
 Area of edema in left flank. 
 
 January 10. Vulva very much swollen, also hips for a distance of 5 or 6 inches 
 to either side. Nodule in front of shoulder is still present. Only a small amount of 
 edema on aspect of body or in left flank.
 
 INFECTIVENESS. 23 
 
 January 11. About 350 c. c. blood drawn from right jugular; 60 c. c. of this was 
 injected immediately into left jugular of donkey 37; the balance was defibrinated, 
 and 60 c. c. injected intravenously into donkey 43. (See records of donkeys 37 and 
 43.) 
 
 January 12. Swelling of vulva and hip not nearly so great as it was yesterday. 
 No edema over ventral aspect of body. Many eruptions still present on shoulders 
 and back. Appetite not as good as usual. 
 
 January 13. Vulva swollen about the same. Hips for a distance of 5 or 6 inches 
 around vulva much swollen. Appetite better. 
 
 January 16. Swelling of vulva slightly reduced; that of hips has increased slightly. 
 
 January 20. Swelling of vulva increased a little over what it had been for the past 
 few days. No change in swelling of hips. A hard nodule about 3 cm. in diameter has 
 appeared at point about 5 cm. to left of anus. 
 
 January 23. Swelling of vulva increased. 
 
 January 31. Animal has an enlargement about 3 inches in diameter by 2 inches 
 in height immediately to left of anus. This enlargement has a hard sensitive border 
 and a soft center about 1 inch in diameter. The vulva is still swollen and edema ia 
 still present on rear of thighs and in left flank. Nodule in front of left shoulder still 
 present. 
 
 February 1. Abscess which has formed at side of anus is broken and is discharging 
 aero-purulent fluid. 
 
 February 2. Abscess has discharged all of its contents. Swelling and skin lesions 
 are about same as last noted. 
 
 February 11. Has a patch of edema about 4 by 5 by 1 inch between forelegs. 
 Vulva and tissues surrounding it much swollen. Abscess completely healed. 
 
 February 17. Vulva and rear of thighs much swollen. Considerable edema over 
 abdomen and between forelegs. Many small eruptions over neck and shoulders. 
 The hair in this region has fallen out. 
 
 February 20. Same as last noted, and in addition a plaque 2 by 3 inches in area on 
 left side of neck. 
 
 February 21. About same as yesterday . 
 
 February 23. Skin disease lesions still present and spreading. Enlargement in 
 front of left shoulder increasing in size. Edema still present between forelegs and 
 abdomen. Vulva still swollen. 
 
 March 8. Portion of hips still swollen. Vulva and loose tissue below it are swollen. 
 Enlargement in front of left shoulder increasing in size. Small enlargement at seat 
 of blood injection. 
 
 March 17. Edema between forelegs and over abdomen. Vulva and loose tissue 
 between it and udder edematous. Enlargement in front of left shoulder same as last 
 noted. 
 
 April 1. Udder and vulva swollen. 
 
 April 10. Same as last noted. 
 
 May 5. Vulva and udder still swollen. 
 
 May 16. Vulva slightly swollen. Swollen area one-half to 1$ inches high and 16 
 inches in diameter surrounding anus and vulva. Both prescapular glands enlarged. 
 
 May 25. Prescapular glands still enlarged. Edema in inguinal region. Vulva and 
 hips swollen. 
 
 May 29. Hips and vulva slightly swollen. No plaques visible. 
 
 June 15. Animal seems to be recovering. Highest temperature noted, 102.4 F. 
 
 July 15. Apparently well. 
 
 August 15. Apparently well. 
 
 September 18. Gave birth to a normal male colt. 
 
 October 10. Served by male donkey 48 to-day, and on four previous occasions, 
 "without infecting the male. 
 
 May 18. Killed to-day. All organs normal.
 
 24 DOURINE OF HORSES: ITS CAUSE AND SUPPRESSION. 
 
 As already mentioned, the blood of donkey 34 was injected into 
 donkeys 37 and 43 on January 11, 1905, the first receiving the whole 
 blood, while the latter received the filtrate. The records of these 
 donkeys which follow show that the virus was successfully held back 
 by the Chamberland filter. 
 
 DONKEY No. 43. 
 
 January 11, 1905. Injected into right jugular with 60 c. c. of filtered blood of donkey 
 34. This blood was drawn at 10 a. m. to-day, was defibrinated, diluted, filtered, and 
 injected at 4.30 p. m. 
 
 Animal is now in fairly good condition and seems to be well in every respect. 
 
 May 29. Up to this date has shown no symptoms, and temperature has not exceeded 
 100.4 F. 
 
 December 9. Served by donkey 48 (by mistake). 
 
 December 26. Female foal born to-day. 
 
 January 11, 1906. Foal and dam killed. No lesions. 
 
 DONKEY No. 37. 
 
 January 11, 1905. Injected into right jugular with 60 c. c. of whole blood of don- 
 key 34. 
 
 January 23. No symptoms of disease. 
 
 January 25. Animal has a plaque about 3 inches in diameter by inch in height 
 on left hip a short distance from root of tail. 
 
 January 28. Plaque on hip still present. No other lesions. 
 
 February 11. Plaque has almost disappeared. 
 
 February 17. The plaque on rear of left hip is now about 5 inches in diameter by 
 1 inch high. 
 
 February 21. Superior portion of neck is much swollen. Patch of edema between 
 forelegs. Edema on thigh still present. 
 
 February 23. Skin eruptions of shoulders; hair beginning to fall out; enlargement 
 about 3 cm. in diameter on front of left shoulder, and a patch of edema between forelegs. 
 
 February 24. Vulva swollen, in addition to symptoms noted yesterday. 
 
 March 2. An enlargement about 4 cm. in diameter is noted at right of vulva. 
 
 March 8. Animal has eruption on neck, and vulva swollen a little. 
 
 March 17. Swelling of vulva has nearly subsided. Legs in region of hock swollen. 
 
 March 23. Large patch of edema 1 to 1$ inches in height extending over sternum and 
 abdomen. Vulva only slightly swollen. 
 
 April 1. Vulva swollen somewhat. Edema still present on abdomen but reduced in 
 height. Left prescapular gland is enlarged. 
 
 April 4. Vulva swollen. No edema on abdomen. 
 
 April 15. Same as last noted. 
 
 April 20. Vulva much swollen. Mucous membrane in region of os uteri is edema- 
 tous. 
 
 May 5. Large patch of edema on chest and abdomen. Vulva swollen, also the 
 tissue between it and the udder. 
 
 May 8. Vulva swollen, an edematous ridge 1 $ inches wide by 1$ inches high extend- 
 ing from vulva to a point on left side of udder where it broadens out into a patch 3 by 4 
 inches in area. Large patch of edema on abdomen ; small abscess formed and broken 
 over posterior surface of knee; left front leg swollen, and a shallow ulcer on anterior 
 surface of hock. 
 
 May 9. Right foreleg swollen, pits on pressure, discharging abscess at posterior 
 portion of knee joint. Vulva much swollen; its mucous membrane presents a some- 
 what granular appearance; swollen ridge noted yesterday is still present.
 
 INFECTIVENESS. 25 
 
 May 10. Has a slight vaginal discharge; has a plaque about 4 by 3 inches by inch 
 immediately in front of left flank. 
 
 May 11. Plaque noted yesterday is still present, and one about 3 inches in diameter 
 by one-half inch high is present a short distance above and in front of it. A third one 
 about 2 inches in diameter by inch high on left hip. Swelling on left front leg is 
 subsiding. Abscess on knee is still discharging. 
 
 May 12. Plaques about same as noted yesterday. 
 
 May 17. Abscess on left knee is still discharging sero-purulent fluid, which has a 
 very bad odor. This leg is swollen between knee and ankle; both prescapular glands 
 are enlarged; vulva only slightly swollen with very little discharge. Several plaques 
 on body. 
 
 May 24. Has patch of edema between forelegs. Vulva still swollen, and plaques 
 seem to be disappearing. 
 
 May 25. Vulva only slightly swollen. A new plaque has appeared in left inguinal 
 region, and old ones have not altogether disappeared. 
 
 May 29. One old plaque is still present on left side; others have disappeared. 
 Abscess on knee still discharging. Vulva still swollen. 
 
 May 31. Vulva is very much swollen. Left hind leg swollen. Old plaque on left 
 side is still present and several new ones have appeared. 
 
 June 1. Vulva much swollen. Swelling on knee reduced. Abscess still discharg- 
 ing, and an extensive patch of edema on abdomen. 
 
 June 3. Has a large amount of edema on abdomen and between fore legs. Abscess 
 still discharging. Ulcers on hocks. Vulva still swollen . 
 
 June 5. Only a small amount of edema on abdomen; abscess not discharging; a 
 few plaques still present; vulva only slightly swollen. 
 
 August 3. Several small plaques present. Highest temperature recorded, 102.2 F. 
 
 September 10. Gave birth to a healthy male colt. 
 
 October 12. Served by male 48 to-day, and three additional times since September 
 21, without infecting him. 
 
 May 18. Killed to-day. All organs normal. 
 
 1 i irh 
 Mare 33, suspected of being in foal, was inoculated on November 4, 
 
 1903, with material containing tiypanosomes obtained from the dog 
 imported from France. Two inoculations were made, 5 c. c. being 
 used subcutaneously in front of left shoulder and 5 c. c. subcutaneously 
 into the left hip. 
 
 MARE No. 33. 
 
 November 8. Has a soft sensitive swelling about 4 by 6 by ^ inches in size at seat 
 of injection in front of left shoulder, and a very flat sensitive swelling about 5 inches 
 in diameter on left hip. 
 
 November 9. The swellings on hip and in front of shoulder have become much 
 smaller. 
 
 November 11. The swellings have increased, are hard and very sensitive. The 
 one in front of left shoulder is about 4 by 5 by 1 inches in size, and the one on left hip 
 is about 8 inches in diameter by $ inch high. 
 
 November 12. The swellings are about the same as yesterday. 
 
 November 16. The swellings have almost disappeared. No lesions to be seen 
 elsewhere. 
 
 November 20. The swellings have disappeared. 
 
 December 1. Has a patch of edema about 6 by 8 by 1J inches in size between the 
 forelegs; also has some edema over the abdomen. Udder enlarged. Hind legs below 
 hocks are edematous. No swellings at seats of injections. Animal seems to be well 
 otherwise.
 
 26 DOURINE OF HORSES: ITS CAUSE AND SUPPRESSION. 
 
 December 2. Has a sharply defined patch of edema about 2 inches high which 
 extends over almost the entire sternum and abdomen. The legs are edematous. No 
 lesions at seats of injections or in vagina. Animal seems to be well otherwise. 
 
 December 3. Same as yesterday. 
 
 December 12. Edema about 2 to 3 inches in height and extends over entire sternum 
 and abdomen. No lesions to be seen in vagina. Animal otherwise appears normal. 
 
 December 15. No further reduction in amount of edema. Animal seems to be well. 
 
 December 23. Still has considerable edema over abdomen. 
 
 December 30. Has been quite lame in left hind leg for several days past. Edema 
 over the sternum is slowly disappearing. 
 
 December 31. The edema is nearly gone. Animal is still quite lame, but appetite 
 is fairly good. 
 
 January 2. The edema has entirely disappeared from sternum and abdomen. The 
 lameness is slowly disappearing and health seems to be good. 
 
 January 6. Very lame in left hip; can bear no weight on this leg, which seems to be 
 very painful. Mare seems to be well otherwise. No lesions to be seen in vagina. 
 
 January 8. Leg seems to be more painful than ever, so much so that she will not 
 stand up long enough to eat all of her morning feed. 
 
 January 11. Seems unable to remain on her feet but a few minutes at a time, but 
 appetite is fairly good. 
 
 January 12. Lameness is slowly becoming worse, and right hind leg seems to be 
 affected also. Appetite seems to be fairly good, but she does not seem able to stand 
 on her feet long enough to eat very much. 
 
 January 15. Unable to get up without assistance, and can not stand owing to weak- 
 ness in lumbar region. Appetite is good. Mucous membrane of vulva is injected. 
 
 January 18. Mucous membrane of vulva and vagina very much congested. Animal 
 unable to get up, lies stretched out and seems to be in considerable pain, but holds 
 head up to eat and has considerable sticky muco-purulent vaginal discharge which 
 contains a few trypanosomes. Temperature is commencing to rise; 103.2 F. at 9 
 a. m., 103.8 F. at 5 p. m. 
 
 January 20. Animal considerably weaker than heretofore; has very little appetite, 
 and a profuse yellowish discharge from vagina, which is still much congested. Rab- 
 bits and rats inoculated with this discharge showed the presence of numerous trypano- 
 somes. 
 
 January 21. Little change since yesterday, but mare is weaker. 
 
 January 22. One sharply defined patch of edema about 4 by 3 by 1 inches in size 
 on opposite side to that on which the animal is lying. 
 
 Is much weaker than she has ever been; respiration accelerated; does not take 
 notice of anything. Temperature at 8.30 a. m., 105.6 F.; at 10 a. m., 106 F.; at 
 1.30 p. m., 106.4 F. 
 
 Has several bed sores which have an offensive odor. Wounds made over jugular 
 for drawing blood do not heal. 
 
 Found dead about 4.20 p. m. 
 
 The post-mortem examination showed the animal to have fallen 
 off gradually in flesh. The skin contains several bed sores involving 
 the adjacent muscles. The heart is normal; left lung hypostatically 
 congested; liver enlarged and friable; kidneys softened, pale, swollen, 
 and contain a few extravasations; spleen darkened, enlarged, and 
 shows several petechise under the capsule; uterus contains an 8- 
 months fetus, which is apparently normal; vagina is edematous, with 
 a gelatinous infiltration of the mucosa; vulva appears swollen and 
 slightly congested, with a gelatinous exudate adhering to its walls.
 
 SYMPTOMS. 27 
 
 The left coxo-femoral articulation shows a roughened erosion on the 
 acetabulum one-eighth by one-third of an inch in size, while the head 
 of the femur contains a similar ulcerated area, which no doubt was the 
 cause of the pain and lameness in this leg. 
 
 Many smear preparations were made and various small experi- 
 mental animals were injected at different times with material from 
 this mare, and although the trypanosomes were elusive and at times 
 exceedingly difficult to find, they nevertheless were usually located. 
 
 SYMPTOMS. 
 
 There are many variations in the symptoms of dourine, and this is 
 particularly true of the disease as it occurs in this country. In order 
 to give a fair idea of the "symptom complex" it will be necessary to 
 describe manifestations which may appear in a number of horses, it 
 being understood that each individual may have several but not all 
 of the symptoms enumerated. Two distinct stages may be noted, 
 which vary somewhat from those described in textbooks, but prob- 
 ably no more than could be expected when differences of climatic 
 conditions and methods of handling are taken into consideration. 
 
 The first stage chiefly concerns the sexual organs, and therefore 
 differs somewhat in the male and female. In the second stage symp- 
 toms indicating an affection of the nervous system are more promi- 
 nent and are not dependent on the sex of the animal. 
 
 Following a variable period of incubation of from eight days to 
 two months, there is seen in the stallion an irritation and swelling 
 about the penis first noticed in the glans. This swelling extends 
 throughout the organ, and the penis may be continually protruded 
 and frequent erections noticed. The edematous swelling also 
 involves the groin, with enlargement of the adjacent inguinal glands, 
 and extends forward along the abdomen. In a few days small 
 vesicles or blisters appear on the penis, which break, discharging a 
 yellowish serous fluid and leaving irregular raw ulcers. Where pri- 
 mary ulcers are in proximity to each other there is a marked disposi- 
 tion to coalesce, a large raw surface with an irregular border resulting. 
 The ulcerative process may form a wound extending almost entirely 
 around the penis. The ulcers show a tendency to heal rapidly, 
 leaving white cicatrices or scars which are permanent. In some 
 cases the urinary meatus is very red and swollen, and according to 
 some observers, especially European, more or less of a thick catarrhal 
 exudate is discharged from its orifice. This condition, however, has 
 been rarely seen in cases in this country, a more or less continuous 
 dripping from the urethra of a yellowish, serouslike discharge alone 
 being present. The stallion retains his full genesic instinct and 
 becomes very amorous when brought in the vicinity of mares. If 
 allowed access to mares in season, service is often impossible, due to
 
 28 DOURINE OF HORSES: ITS CAUSE AND SUPPRESSION. 
 
 the fact that a complete erection of the penis does not occur. The 
 testicles may be involved and tender to pressure, and abscess forma- 
 tion may occur, with sloughing. 
 
 In the mare the first symptoms may be so slight as not to be 
 noticed by the owner. This is especially so where the mares are 
 running on the open range and not seen by the owner for long periods. 
 In fact, the first knowledge in such instances frequently comes from 
 finding a diseased mare astray in the foothills, having been driven 
 out of the band by the stallion. This custom of getting rid of unde- 
 sirable or diseased mares is quite general with the leader of a harem 
 of mares running at large in distinct bands on the western ranges. 
 However, the disease, being the result of copulation, begins with 
 swelling and inflammation of the vulva and vagina. The labia are 
 continually everted, exposing the clitoris, which is constantly in a 
 state of erection. There will also be a muco-purulent discharge like 
 that coming from the penis of the male, which may be slight or pro- 
 fuse in quantity, agglutinating the hairs of the tail. The mare will 
 switch the tail, appear uneasy, and urinate frequently. Shortly 
 papules and vesicles appear on the external vulva, as well as on the 
 mucosa of the vulva and vagina. These vesicles soon rupture, but 
 before doing so the contents undergo a change from a transparent 
 to a purulent fluid. The rupture of these pustules is the initial 
 stage in the formation of deep, angry ulcers. These ulcers show a 
 tendency to heal rapidly, but invariably leave a cicatrix, which is 
 permanent, causing a slight puckering of the tissue. On the dark 
 skin on the external vulva the scars will always be white, more or 
 less circular in outline, from one-eighth to one-half inch in diameter, 
 and pitlike, similar to the depression in a pockmark. This depig- 
 mentation of the skin about the external genitals, due to healing of 
 the ulcer, is permanent and not temporary, as in coital exanthema 
 and other affections simulating it. Edematous infiltration of the 
 perineum and the mammary gland frequently occurs. 
 
 Sometimes, and especially in the mare, the above-described lesions 
 tend to disappear gradually, and in case the mare is not served again 
 the disease may remain in abeyance for months or a year. The 
 apparent recovery, however, is not permanent, and any excessive 
 work or excitement, and especially being served by a stallion, even 
 if he be healthy, may set up the disease anew. In case an affected 
 mare conceives, she is liable to abort at any time during her term of 
 pregnancy. When the fetus is carried to full term, it occasionally 
 is a weak and imperfectly developed foal; but in this country many 
 fine colts have been born to affected mares. 
 
 The nervous or constitutional disturbances of the second stage may 
 not come on for months or even a year after the appearance of the 
 local lesions, and are similar in both male and female. They consist
 
 But. 142, BUREAU OF ANIMAL INDUSTRY, U. S. DEPT. OF AGRICULTURE. 
 
 PLATE IV.
 
 BUL. 142, BUREAU OF ANIMAL INDUSTRY, U. S. DEPT. OF AORIULTURE. 
 
 PLATE V. 
 
 -- -s 
 
 
 I
 
 POST-MORTEM LESIONS. 29 
 
 of a general nervous disorder with staggering, swaying gait, especially 
 in the hind limbs. The animal becomes extremely emaciated, partic- 
 ularly in the hind quarters, and the abdomen assumes a " tucked-up" 
 appearance. (See PI. Ill, fig. 1.) The first indication of paralysis 
 will be noted in traveling, when the animal fails to pick up one of 
 the hind feet as freely as the other. There is a tendency to drag the 
 foot partially, which will wear off the toe more than normal. This 
 condition may shift from one hind foot to the other, or both may 
 become affected simultaneously, at which time knuckling is a com- 
 mon symptom. (See PI. Ill, fig. 2.) Only occasionally are the 
 nerves of the front extremities and the face affected, the latter find- 
 ing expression in paralysis of an ear, eyelid, nostril, or lip. (See PI. 
 IV, fig. 1.) Twitching of the superficial muscles has also been noted 
 in several instances. Urticarial eruptions oc plaques may break out 
 over various parts of the body. These swellings, which prior to the 
 recent Iowa outbreak had been observed in only a few cases in this 
 country, disappear in a few days, only to reappear at some other 
 point. In the outbreak just referred to almost every horse showed 
 two or more plaques. They are sharply defined, round, flat, edema- 
 tous infiltrations of the papillary layer of the skin, about the size of a 
 half dollar, or may be even larger. Some have a depressed center 
 and an elevated periphery. When punctured, a bloody serum exudes 
 from the cut surface. The usual locations of these plaques are the 
 croup, belly, and neck. (See PL V.) There may also be noted 
 pruritis of the skin, which causes the animal to rub itself fre- 
 quently. White spots appear on the hind legs and in the region of 
 the perineum, as a result of the discharge from the penis and vagina 
 coming hi contact with and causing a depigmentation of the integu- 
 ment. (See PI. IV, fig. 2.) The temperature of the animal seldom 
 goes above 101 or 102 F. Labored breathing is occasionally noted. 
 In some cases the glands under the jaw swell and a discharge appears 
 from the nostril simulating glanders. When the paralysis of the hind 
 limbs starts to appear, it usually progresses rapidly, the horse goes 
 down, is unable to rise, and dies in a short time from nervous exhaus- 
 tion. Up to the last, however, the appetite remains good, and the 
 stallion will show a desire for the mare, although service is impossible, 
 as the horse can neither get a complete erection nor raise himself on 
 his hind legs. 
 
 POST-MORTEM LESIONS. 
 
 On autopsy there are noted swelling and gelatinous infiltration of 
 the mucosa of the vulva and vagina, together with marked hyperemia. 
 The uterine mucosa is thickened, infiltraced, and corrugated, resem- 
 bling the mucous membrane of the large intestine in Johne's disease. 
 Ulcers are sometimes present, although rarely so in the disease as it
 
 30 DOURINE OF HORSES: ITS CAUSE AND SUPPRESSION. 
 
 exists in this country. The mucous membrane is not infrequently of 
 an orange-colored hue, covered with a muco-purulent exudate and 
 occasionally supports small, irregular yellowish patches of mucoid 
 degeneration. The ovaries are frequently involved, and their paren- 
 chyma may be the seat of hemorrhage and large blood clots may be 
 found within their capsules. The skin in the region of the perineum 
 where the discharge has come in contact with it is depigmented, 
 leaving irregular white patches. In the male the penis is usually 
 found to be enlarged, although in some cases it is normal in size. It 
 frequently contains ulcers and scar tissue both on its surface and in 
 urethral canal. The sheath is also tumefied and the skin thickened. 
 The testicles in some cases are soft and atrophied, while in others just 
 the opposite is found. Adhesions may occur between the tunica 
 vaginalis and the tunica propria. In nearly all cases the scrotum is 
 more or less infiltrated. The lymphatic glands in the inguinal region 
 are also inflamed, and in many cases may be plainly visible as irregular 
 wavy lines under the skin. There is also a yellow gelatinous exudate 
 beneath the skin in those areas where plaques were situated just 
 before death. In cases of long duration there is more or less marked 
 atrophy of .the muscular system, a condition naturally following the 
 paralysis which precedes death. 
 
 The changes in the spinal cord have been principally studied by 
 Thanhoffer. The meninges, especially the pia mater, are severely 
 congested; in some places adhesions have taken place between the 
 pia and the cord, while in others the pia is severely congested. The 
 central canal in the spinal cord is dilated in certain points and may 
 contain an excessive quantity of fluid. On section softened areas 
 may be found in the substance of the cord, and dark red spots may 
 also be present, indicating hemorrhage. The supporting framework 
 of the spinal cord (neuroglia tissue) is hypertrophied, especially 
 around the central canal, producing sclerosis, or hardening of the cord. 
 The large spinal nerve cells are involved, and the nuclei frequently 
 undergo granular disintegration. In other cells the axicylinder pro- 
 cess is affected and its outline is wavy and tortuous. According to 
 Marek, the change observed in the nerves is a polyneuritis. The 
 ventricles of the brain also contain an excessive amount of fluid. 
 In summarizing, we may say that there is a general hydrops of the 
 central nervous system with a tendency to degeneration in the spinal 
 cord, and multiple hemorrhage formation in the substance of the 
 cord with slight leucocytic infiltration. The skeleton is also affected, 
 and the bones may be softened. The medullary substance (marrow) 
 is congested, and hemorrhages and erosions may be seen on the 
 articular cartilages of the joints. A discoloration of the synovia, due 
 to red blood cells, is frequently seen, giving it a peculiar pinkish 
 coloration.
 
 COURSE OF THE DISEASE PROGNOSIS. 31 
 
 The intestines usually contain but small quantities of alimentary 
 matter, and ulcers may sometimes be found in the mucous membrane. 
 The peritoneum is hypertrophied and has a yellowish cast, due to 
 the serum it contains in its meshes. The mesenteric and inguinal 
 lymph glands may be enlarged and softened or small and firm in con- 
 sistency. The liver contains areas of fatty degeneration, is severely 
 congested, and may contain minute hemorrhages in its parenchyma. 
 The spleen may also contain these petechia, but it is usually only 
 slightly enlarged, soft, and doughy, although it may be normal in 
 size and appearance in the horse. In experimental animals, how- 
 ever, and particularly white rats inoculated with trypanosomes, 
 this organ is enlarged to two to three times the normal and very 
 severely congested. 
 
 The kidneys are enlarged and soft in consistency and show the 
 presence of parenchymatous degeneration. The lungs are almost 
 invariably very much congested, and suppurative foci may some- 
 times be found in their substance. The blood is watary and forms 
 imperfect soft clots, the red blood cells having undergone extreme 
 .diminution in number, although there is a decided leucocytosis with 
 a marked increase in the quantity of tymphocyte cells. 
 
 COURSE OF THE DISEASE. 
 
 The course of the disease, as will be seen from the symptoms, is 
 extremely variable, and may cover a period ranging from nine 
 months to two years. At the commencement of the attack the 
 genital symptoms alone are observable. These, however, sooner or 
 later become complicated by the appearance of the systemic or 
 nervous disturbances, including loss of flesh, staggering gait, and 
 paralysis of the posterior extremities. These symptoms gradually 
 become intensified until the animal, reduced to skin and bone, is 
 unable to rise, and death at last results from exhaustion, lack of 
 nutrition, or from septic infection. This course is markedly influ- 
 enced by the condition and environment to which the animal has been 
 subjected. Bad weather, exposure, insufficient food, and compli- 
 cating diseases like influenza, distemper, or in fact any condition 
 whicli tends to lower the vitality of the animal, will hasten the 
 termination of the disease. On the other hand, good care and 
 abundant food will prolong life, and in this country has even resulted 
 in recovery. It is also possible under favorable conditions that an 
 animal may have dourine in the latent form for several years without 
 manifesting any alarming symptoms and yet be a source of danger. 
 
 PROGNOSIS. 
 
 Although now and then a case of dourine may recover, as a rule 
 the disease is present merely in a latent state, and the excitement
 
 32 DOURINE OP HORSES: ITS CAUSE AND SUPPRESSION. 
 
 caused by copulation is very likely to cause it to reappear with 
 renewed vigor. The outlook, therefore, from a prognostic point is 
 always to be considered unfavorable, and in a country where a rela- 
 tively small number of cases appear temporizing methods of suppress- 
 ing the disease are not warranted. 
 
 DIFFERENTIAL DIAGNOSIS. 
 
 In countries where dourine is the only infection caused by 
 trypanosomes, the diagnosis is made certain by the demonstration 
 of these parasites; but, as has already been noted, this is connected 
 with considerable difficulty, as the parasites in the blood appear very 
 seldom and then only in small numbers. They are most constant 
 in the serous fluid of the cutaneous plaques and in the edematous 
 swellings and muco-purulent discharges of the vagina, but even here 
 they appear only periodically. While it is a comparatively easy 
 task to diagnose the disease in its acute form if ulcers are present on 
 the genitals and edematous patches on the skin, those cases which 
 have apparently recovered, or which may more properly be termed 
 chronic, present many difficulties. The diagnosis is much easier ii 
 several animals are affected at the same time. 
 
 Coital exanthema or vesicular exanthema is the disease most fre- 
 quently mistaken for dourine, as both appear shortly after the act of 
 copulation with nearly similar symptoms. During the ulcerative 
 stage and without a history of the case, it is somewhat difficult to 
 make a differential diagnosis. However, the period of incubation in 
 coital exanthema is shorter, the ulcers produced by the ruptured 
 vesicles are more superficial and heal more rapidly, the resulting 
 depigmention is only temporary, and permanent scars on the mucosa 
 of the genitals are not observed, neither does it cause abortion or 
 terminate in paralysis. 
 
 At times the initial stage of dourine is confounded with a traumatic 
 inflammation of the genital organs. However, the traumatic origin 
 may easily be excluded, on the one hand, through the lack of observ- 
 able lesions; and, on the other, through the character and persistent 
 continuance of the edematous swelling. 
 
 The plaques of dourine are similar to urticaria, but in the latter 
 disease lesions of the genital tract and nervous symptoms are absent, 
 and there is no evidence of contagion. 
 
 The paralysis of the hind quarters is only characteristic for dourine 
 when taken in connection with other nervous symptoms. Among 
 other diseases showing a similar paralysis may be mentioned azoturia, 
 forage poisoning, and swamp fever, but these diseases are as likely to 
 affect geldings as stallions or mares. They may also be discriminated 
 from the paralysis of dourine mainly through the absence of lesions
 
 DIFFEKENTIAL DIAGNOSIS. 33 
 
 of the sexual organs. In the latter disease the accessory conditions, 
 such as the infection of several animals shortly after the act of copu- 
 lation, as well as the different aspect of the symptoms in the affected 
 animals, offers a sufficient foundation for a correct diagnosis. 
 
 Although the vaginal discharge of leucorrhea may resemble that of 
 dourine, the characteristic ulcer or cicatrix of dourine is always 
 absent. The nearest approach to it is a raw and abraded condition 
 of the lips of the vulva due to the irritating properties of the discharge. 
 Nervous symptoms terminating in paralysis are not observed. 
 
 On the western range it is not unusual to see several stallions 
 ranging with a small band of mares. This is especially so on the 
 Indian reservations, where in several cases as high as 40 per cent of 
 the band were stallions. Under such conditions a mare during the 
 period of heat is served repeatedly. The vaginal mucous membrane 
 becomes a livid red and slight abrasions are not uncommon. If exam- 
 ined shortly after the subsidence of the period of heat the vaginal 
 mucosa will present a mottled variegated appearance, being red, 
 dark red, and even purple in patches. 
 
 In the alkali districts during hot weather it is not uncommon to 
 see horses with extensive chafing between the thighs, in the folds of 
 skin on either side of the vulva, or on the loose folds of the sheath, 
 as a result of the natural secretions mixed with alkali dust. Exten- 
 sive depigmentation of the affected area is the result. Such depig- 
 mented areas and those resulting from abrasions or lacerations are 
 irregular in outline and, unless from a deep laceration, are not per- 
 manent, whereas those due to dourine are usually circular in outline, 
 cicatricial in character, and permanent. Natural depigmented areas 
 are common in the so-called " Arabian" horses of the western range 
 and in those animals with an admixture of the blood of the pinto 
 pony, a species of equine albino very popular among the Indians. 
 
 Ulcers on the mucosa of the genitals may be mistaken for glanders, 
 especially when the lymph vessels and lymph glands are simultane- 
 ously inflamed. In this case the further progress of the disease, 
 serum diagnosis, mallein test, or inoculation experiments will fur- 
 nish definite diagnostic information. 
 
 Dourine may also be mistaken for surra in countries where the 
 latter disease prevails, but as surra does not exist in the United States, 
 it need not be considered from a differential standpoint in this 
 country. 
 
 Phlegmonous inflammation and pyemic abscesses, with swelling of 
 the adjacent lyrnph glands, may sometimes occur after copulation in 
 mares and stallions which are suffering from an ichorous purulent 
 discharge, but the absence of further progress of the condition will 
 easily decide the diagnosis.
 
 34 DOURINE OF HORSES: ITS CAUSE AND SUPPRESSION. 
 
 Melanotic tumors appearing about the anus and vulva of gray 
 horses and carcinoma of the penis have been the cause of several 
 inspections for suspected dourine, but they should never be mis- 
 taken for lesions of dourine by anyone in the least familiar with this 
 disease. 
 
 TREATMENT. 
 
 Little benefit can be obtained from the medicinal treatment of 
 this chronic malady, nor is such treatment desirable in this country, 
 where the disease has existed only in restricted areas and where 
 sanitary considerations demand its prompt extirpation. Some cases, 
 however, have been observed where improvement and recovery fol- 
 lowed local treatment when applied in the early stages of the infec- 
 tion. When, however, any systemic symptoms appear, drugs seem 
 to be useless and deaths follow after very varying periods of time in 
 different cases. 
 
 As the infection takes place through the genital apparatus, the 
 thorough application to these parts of antiseptic solutions with the idea 
 of destroying the trypanosomes before they obtain access to the gen- 
 eral circulation may be looked upon as the most rational treatment. 
 This, although practicable in the male, is extremely difficult to 
 accomplish thoroughly in the female. Toward this end corrosive 
 sublimate, 1 to 2,000, or 2 per cent solution of carbolic acid or creolin, 
 should be injected into the vagina of the mare and the sheath and 
 penis of the stallion immediately upon the first appearance of inflam- 
 mation of the genitals following the act of coition in infected localities, 
 or where for any reason the presence of the disease is to be suspected. 
 
 After the systemic symptoms of urticarial eruption and paresis 
 with rapid loss of flesh in spite of a good appetite begin to appear, 
 the symptomatic treatment with stimulants and alteratives has been 
 recommended, but is of very slight value except to prolong the life 
 of the patient. Among such drugs may be mentioned strychnin (1 
 grain three times daily) or potassium iodid (2 to 5 drams daily) for 
 their alterative action. Marchal, of the remount depot, Constantine, 
 Algeria, reports on the treatment of six stallions with cacodylate of 
 soda, 1 gram in 5 c. c. of distilled water, given in two doses daily 
 subcutaneously for five consecutive days with seven days interval, 
 while others have recommended atoxyl, and recently Meissner has 
 been experimenting with arsenophenylglyzin. Although the statis- 
 tics of these lines of treatment are very limited, they seem to give 
 very promising results and at least deserve further trial in those 
 foreign countries where the disease is indigenous. 
 
 During the course of treatment care should be taken not to excite 
 the sexual ardor of the patient, as this under all circumstances aug- 
 ments the symptoms, and indeed the act of copulation, hi the mare 
 especially, may revive the symptoms of the disease in the acute
 
 METHOD OF EEADICATION. 35 
 
 stage when to all external appearances the animal had recovered 
 from a previous infection. 
 
 METHOD OF ERADICATION. 
 
 Sanitary measures looking to the eradication of dourine must 
 depend on the principle that horses infected with dourine should be 
 excluded from breeding. This action is well founded, for, in spite of 
 the possibility of cure, there are as a matter of fact frequent relapses, 
 and further, trypanosomes may exist for months in the sexual organs 
 of the apparently cured animal. Therefore, it is very essential to 
 destroy the diseased mares and to castrate the affected stallions. 
 The objection to spaying mares is that if they should be sold and 
 attempt to breed, the disease may be contracted by the serving 
 stallion and thus spread. On the other hand, stallions which are 
 castrated before the appearance of paralytic symptoms become sound 
 and well, but the stallions even after castration will frequently serve 
 mares. They should therefore be prevented from mingling with 
 mares for a month after the ulcers are healed. 
 
 Dourine, being conveyed solely by coitus, is not a difficult disease 
 to stamp out in a farming community such as in Illinois, where the 
 first outbreak occurred, or in Iowa, where the infection appeared in 
 1903 and 1911. But when the disease reached the open range and 
 infected horses which ran in the foothills and "bad lands " of Nebraska 
 and South Dakota, respectively, the difficulties increased manyfold, 
 as inspections in many cases could be made only at the spring round- 
 up. Even then there were but frequently but 60 to 70 per cent of 
 the horses gathered up, owing to the rough condition of the land and 
 the impossibility of seeing the stray animals. 
 
 After mature consideration a definite policy was decided upon 
 which consisted in the slaughter of diseased mares, castration or 
 slaughter of diseased stallions, castration or quarantine of exposed 
 stallions, and the frequent reinspection of exposed mares. It was 
 further decided to keep a sufficient number of men in the infected 
 districts to carry out this policy, and Dr. E. T. Davison was placed 
 in charge of the work of eradication with headquarters at Rushville, 
 Nebr. To his capable and energetic efforts must be largely credited 
 the satisfactory results which have been accomplished. 
 
 With the view of preventing the shipment of diseased animals 
 from the infected districts the Secretary of Agriculture issued an 
 order under date of January 20, 1903, prohibiting the transportation 
 or movement of any horses in the counties of Dawes, Boxbutte, 
 Sheridan, and Cherry, in the State of Nebraska, and in the Pine 
 Ridge and Rosebud Indian Reservations and the counties of Custer 
 and Fall River, S. Dak., to any other State or Territory or the District 
 of Columbia, unless first inspected by an inspector of this bureau 
 and accompanied by a certificate issued by the said inspector.
 
 36 DOUEINE OF HORSES: ITS CAUSE AND SUPPRESSION. 
 
 On March 10, 1903, the Secretary of Agriculture, with the con- 
 currence of the Secretary of the Interior, issued an order which was 
 posted throughout the above-named Indian reservations prohibiting 
 any stallion or stallions from running at large within the bounds of 
 these reservations, also directing that any uncastrated male horse 
 1 year of age or older found running on the range or at large in these 
 reservations be castrated, and that all stallions belonging to owners 
 living on Whito Clay Creek, or within 1 mile thereof, should be either 
 castrated or kept under close quarantine until further orders; also 
 prohibiting, furthermore, the breeding of horses in herds in which 
 diseased animals had been found, under any circumstances, whether 
 in fenced pastures, inclosures, or otherwise; and directing, with a 
 provision for appraisement and indemnity to owners, that any animal 
 or animals showing symptoms of dourine or known to have been 
 exposed to the disease should, in the discretion of an inspector or 
 employee of the Department of Agriculture, be immediately quar- 
 antined, and maintained in quarantine at the expense of the owner 
 or owners until released by the inspector or condemned and slaugh- 
 tered. A statement was also included to the effect that any person, 
 company, or corporation knowingly violating the provisions of this 
 order would be guilty of a misdemeanor, and on conviction liable to 
 a fine of not less than $100 nor more than $1,000, or to imprisonment 
 not more than one year, or to both such fine and imprisonment. 
 
 As a result of the thoroughness of method followed in the pros- 
 ecution of this work, all the diseased animals in Nebraska were soon 
 detected and either destroyed or castrated. But cases continued to 
 appear on the Pine Ridge Reservation with disconcerting frequency 
 as a result of the many difficulties attendant upon range inspection. 
 With a view of handling this work of eradication to better advan- 
 tage, a number of veterinarians, including the writer of this paper, 
 were sent to the Pine Ridge Indian Agency in June, 1903, for the 
 purpose of making inspections at the time of the annual round-up. 
 Inspection camps were established, one veterinarian and an expe- 
 rienced roper being assigned to each of the five districts on the res- 
 ervation Wakpamini, White Clay, Porcupine, Wounded Knee, and 
 Medicine Root. All the animals were rounded up in each district, 
 and all diseased mares as well as affected stallions, which were of the 
 inexpensive broncho type, were purchased and killed, while the 
 healthy stallions were castrated unless the owner agreed to keep the 
 animal off the open range. In this case the stallion was tagged and 
 kept quarantined on the premises. The five round-up parties grad- 
 ually worked toward Pass Creek, where the final round-up took place. 
 At this time all animals which estrayed from one district to the other 
 during the year were returned and animals which strayed in from 
 the adjacent sections of Nebraska and South Dakota were claimed 
 by owners and removed by them after inspection. This arrangement
 
 METHOD OP ERADICATION. 37 
 
 made possible the inspection of practically all the horses running at 
 large on those ranges. Thus the advantages to be gained were 
 numerous, and large numbers of animals which habitually ran at 
 large on the open range, a great majority of which had never been 
 handled, were subjected almost at the same time to careful veterinary 
 examination, as in the case of those usually kept in barns or inclosed 
 pastures. 
 
 During the round-up season from June 1 to June 30, 1903, 9,455 
 horses were examined; 173 were slaughtered because of showing 
 evidences of the disease, 6 of which were stallions and 167 mares. 
 In addition, 1,270 stallions running at large, these being the most 
 effective spreaders of the disease, were castrated, and 185 stallions to 
 be used for breeding purposes were tagged for identification. During 
 the year the total number of animals inspected was 16,287; number 
 found diseased and slaughtered, 511; number quarantined as sus- 
 picious, 277; number of stallions castrated, 1,889. The average 
 price paid by the department for animals slaughtered because of 
 being diseased was $17.52. Castrations, having been performed by 
 employees of the bureau, incurred no expense, and because of this 
 operation the probability of the transmission of the disease through 
 the animal operated on was removed. Some of the Indian owners 
 objected strenuously to the castration of their pinto stallions, but as 
 a rule very little opposition was met from them, although many 
 regretted the prospects of only a few "papoose ponies" the following 
 season. All stallions left for breeding purposes were tagged with a 
 quarantine tag, kept under quarantine restrictions, and regularly 
 inspected, so that should the disease develop at any point it could 
 be promptly detected and stamped out. This same systematic 
 policy was followed during the next few years in this section. 
 
 Notwithstanding the subsequent failure of any cases to appear, 
 constant vigilance was kept over the horses in the infected sections 
 to make sure that none of the contagion persisted. In order to make 
 it an incentive to report any diseased animals which might have been 
 hidden by owners, an order was issued by the Secretary of Agriculture 
 on April 15, 1907, offering a reward of $50 for authentic information 
 leading to the discovery of the ownership and location of a stallion or 
 a jack affected with dourine, and the sum of $25 for similar informa- 
 tion leading to the discovery of a female animal affected with the 
 disease in the quarantined district, provided that when more than 
 one diseased animal should be found belonging to the same owner, 
 or on the same premises, only one reward should be paid. This 
 reward was offered in addition to the usual compensation to the 
 owner. Notwithstanding that this order has been in force since 1907, 
 not one case of dourine has been found in that district, and conse- 
 quently no reward has ever been claimed. Numerous suspected
 
 38 DOURINE OF HORSES: ITS CAUSE AND SUPPRESSION. 
 
 cases, however, have been reported from time to time since 1906 in 
 different sections of the country by veterinarians and horsemen, but 
 with the exception of the recent Iowa cases they have been shown on 
 investigation to have been some other disease simulating dourine in 
 some particulars, and usually proving to be coital exanthema. 
 
 Investigations have been made in various parts of South and North 
 Dakota, Nebraska, the Indian reservations, Washington, Oregon, 
 Wyoming, Oklahoma, Utah, and Montana. A careful inspection has 
 also been made of the range horses in some of the principal range 
 States, several thousand animals having been inspected in such 
 States in the round-up work, with the assistance of veterinary 
 inspectors engaged in other lines of field service, such inspections 
 having been made for the detection of scabies, glanders, and dourine. 
 The general method has been to have the horses in any section of the 
 country that has ever been regarded with suspicion rounded up 
 during the breeding season and examined. In the States of Montana 
 and Wyoming the horses on the Indian reservations have likewise 
 been examined, not because of disease having been reported among 
 the Indians' horses in these States, but because of the fact that if 
 there were any disease in the country the conditions prevailing on 
 the Indian reservations would be likely to furnish an ideal medium 
 for its development and dissemination. For many years the Crows, 
 Arapahoes, Sioux, and Shoshones have journeyed back and forth in the 
 fall of the year between the Sioux Reservation at Pine Ridge and ths 
 Wind River Reservation in central Wyoming and the Crow Reservation 
 in southern Montana. It is their custom to leave some of their horses 
 as gifts to their friends, and it was the possibility that some of these 
 animals might have been affected with dourine that caused such 
 careful inspections to be made at the neighboring Indian reservations. 
 Representative herds of range horses have likewise been examined, 
 even when such herds have never been regarded as suspicious, and all 
 herds that were ever regarded with suspicion were kept under sur- 
 veillance for several years. 
 
 In the eradication of a disease like dourine, especially when it is 
 confined to a relatively small area, compensation for the affected 
 animals destroyed has a very wholesome influence on the owner in 
 inducing him to notify the proper authorities of the presence of 
 suspected cases of the disease. In many instances the diseased 
 animals are capable of doing some work, and unless they are bred 
 there is no danger to other animals from them. It is this danger 
 of being bred which makes it essential that they should be destroyed. 
 The existence of this disease is a great menace to the horse industry, 
 and speedy eradication wherever it is discovered is therefore very 
 important. 
 
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