key: cord-0040503-ntikbuer authors: Wakenell, Patricia title: Management and medicine of backyard poultry date: 2016-04-15 journal: Current Therapy in Avian Medicine and Surgery DOI: 10.1016/b978-1-4557-4671-2.00024-0 sha: 73cf0208a38f3deecde96ea5e25ee44457d3d961 doc_id: 40503 cord_uid: ntikbuer nan The term "poultry" includes all species of birds that can be consumed for food. Traditional poultry species are the chicken, turkey, duck, and goose. Other species such as pheasants, quail, chukar partridges, pigeons, guinea fowl, and ratites have variable popularity dependent on cultural tradition, geographic location, and availability. "Backyard" or "pet" poultry loosely refers to any of the above species of birds that are maintained for pleasure and/or small-scale sale of birds, meat, or eggs. Often included are those birds owned by breeders and exhibitors of fancy poultry and small commercial operators selling to niche markets (e.g., live bird markets, range eggs, local production). In contrast, the commercial poultry industry is a billion dollar business involving large numbers of birds worldwide. The industry is split into meat (broiler chickens, turkeys, ducks, and geese) and egglaying (table-egg and breeder) types of birds. Large meat-bird operations are generally vertically integrated-the company controls all aspects of production from hatch to processing. Chicken farms maintained for table-egg production are often individually owned, but may market their eggs cooperatively. Breeding is centralized with only a few primary breeders controlling the pedigreed genetic stock. Commercial companies often employ contract farms that are owned by an individual farmer; however, the birds belong to the larger commercial entity. Young female chicks are called pullets, young males are called cockerels, adult males are called cocks or roosters, and adult females are called hens. A genetic female chicken with a male phenotype is called a pollard. Broiler is a meat chicken approximately 2.27 kg (5 pounds) live weight at slaughter and a roaster is a meat chicken 2.72 to 3.63 kg (6 to 8 pounds) live weight at slaughter. Chooks are the popular Australian term for chickens. A capon is a castrated male. Alektorophobia is the fear of chickens. The pecking order is a descriptive term for the dominance hierarchical system of the social organization in chickens. Chickens that have no feathers growing from their shanks are referred to as clean legged, whereas feather-legged breeds, such as Cochins or Brahmas, do have feathers. The crest refers to the puff of feathers on the heads of breeds such as Houdan, Silkie, or Polish, and is also called a "topknot." Feathers that curl rather than lay flat are referred to as frizzle feathers, and this term is also a common show category. The saddle is the part of a chicken's back just before the tail. The shank is the part of a chicken's leg between the foot and ankle, called the tarsometatarsus. A sex feather is a hackle, saddle, or tail feather that is rounded in a hen but usually pointed in a rooster. Sickles are the long, curved tail feathers of some roosters. Turkeys have a snood, which is a long fleshy appendage attached to the face behind the nares. The snood has no known use but can be raised and lowered at will. Cannibalism is the general term used to describe chickens eating each other's flesh, feathers, or eggs. A pickout or peckout specifically describes cannibalism at the vent. Hatch refers to either the process by which a chick comes out of the egg or a group of chicks that come out of their shells at approximately the same time. A batch of eggs that are hatched together, either in a nest or in an incubator, is termed a clutch. A nest egg is an artificial egg placed in a nest to encourage hens to lay there. A straight run refers to a clutch of newly hatched chicks that have not been sexed. A hen that is no longer laying well is referred to as spent. Tiny eggs that have been quickly passed through the oviduct without reaching full size may be referred to as fart eggs, rooster eggs, or oops eggs. Poultry are adaptable to a wide variety of housing, and there are many designs to the buildings mostly because of aesthetic reasons rather than a specific need. Generally, the variables that should drive the choice of housing are climate, bird type, number of different species owned, and neighbors. Housing that has an outdoor component will require protection from predators with a fenced roof and fenced siding and side fences set into the ground at least 1 foot (30.5 cm). [1] [2] [3] Most adult poultry are able to withstand climate changes, with the exception of extremely hot or cold regions. If birds are not ill and are completely feathered (not in molt), heating of buildings is not required (certain breeds can be more cold resistant than others). In fact, housing is often sealed too tightly to retain heat, resulting in lack of adequate ventilation, which causes the onset of respiratory disease. Ventilation is crucially important in all climates. 2 If bird density is high, then better ventilation and more frequent cleaning are necessary. Lack of proper ventilation will result in the buildup of ammonia. High levels of ammonia destroy the cilia on the trachea and allow viruses and bacteria free entry into the lower respiratory tract. In hot climates, forced ventilation (fans) and misters may be necessary to reduce heat. Swamp coolers that cool air by forcing the air over cold water can be inexpensive and beneficial. In cold climates, often the combined body heat of the birds will be sufficient to keep them warm. Additional heat can be provided by a red heat lamp often used for the posthatch period or heated floor mats (Figure 15-1) . For both types of heating, extra caution must be taken to not overheat the birds or cause a fire hazard from flammable materials (shavings and wood) touching a heat source. The flock behavior will be evidence of overheating. If the heat is a point source, birds will crowd away from the source. With central heat, the birds will crowd near exits, windows, and outside walls. If birds are housed entirely outside, a source of shade is necessary. If birds are raised for show, sun exposure can cause the feathers to change color and result in disqualification. All housing should be predator proof. This may require sinking walls 12 or more inches (30.5 cm) in the ground, using concrete aprons surrounding the buildings, or raised wire floors. Bird type will help determine the type of housing required. Most breeds of chickens are hardy although meat-type birds are usually sturdier than egg layers. Show breeds often do not have hybrid vigor and require heated or cooled housing. Be sure to check the normal space requirements for the birdsthese may not be exclusively determined by the size of the bird but also by activity levels. Commercial breeds of turkeys often will be frightened by loud and unusual noises, sometimes causing them to pile in corners and suffocate. Heavier breeds can damage their feet jumping down from perches that are too high and smaller birds can become trapped in corners and small spaces. For all perching birds, perches need to be round, rough, and placed so that when the birds jump down they will not land on hard surfaces or sharp objects. Covering wooden dowels with artificial turf helps provide the roughness for removing extra keratin on the surfaces of the feet (Figure 15 -2). If birds are nesting, at least two nest boxes for flocks of three to five hens and one additional nest box for every two to three hens will help reduce fighting for nest space. Mixing species of birds is a common, but risky, practice in backyard operations. Certain species are more aggressive and "lifestyles" may not be compatible (ducks and geese water play, creating an environment that is too moist for chickens). Some species can carry diseases that do not affect them but will be harmful to other species (e.g., histomoniasis). It is best to have individual housing units for each species. If this is not possible, keep the most valuable (economically or emotionally) species in separate housing. In highly populated areas, both poultry and human neighbors are a concern. Poultry create a tremendous amount of dust and feather debris and are a magnet for flies and other insects. Indoor housing reduces these problems and noise concerns. Many communities ban ownership of roosters and peafowl. Neighboring poultry are a disease risk, and housing should be placed as far away as possible and upwind from these areas. Chickens will destroy all vegetation, so the outside area is often either dusty or muddy. Absorbent material, such as wood shavings, can be helpful for controlling wet ground. It is always a good practice for clients to use the same degree of care in choosing the species and/or breed of poultry as they would exercise in choosing any other companion animal. 2,4 Commercial types of birds are genetically selected to optimize their function, meat or egg production, and should not be recommended for the average backyard operation. A commercial broiler is genetically selected to reach market weight in 6 to 7 weeks and will continue to grow if not processed at that time. Without significant feed restriction, "old" broilers will rapidly outgrow the ability of their legs and cardiopulmonary systems to support their weight. Most noncommercial chicken breeds are dual-purpose breeds that offer both good egg production and adequate meat. Generally, laying-type breeds are more active and lighter weight but can be more aggressive. Meat breeds are less commonly kept in backyard Probably the largest determinant to the decision of buying hatched chicks or hatching your own is the size of the flock that is desired. For small flocks, inexpensive incubator/ hatchers that are easy to operate are available either at farm stores or through mail-order catalogs. When first starting out, as many as 50% of the eggs may not hatch, making egg space a concern if a large hatch is needed. Most inexpensive incubators have good temperature control but inadequate control of humidity. 5 Chicken eggs can withstand shifts in humidity during incubation. Other species such as turkeys, however, are much more sensitive to fluctuations in humidity during incubation. In the commercial industry, chicken eggs are switched from the incubator to the hatcher at 18 days of embryonation (incubation to hatch 5 21 days). This is done primarily to keep down and egg debris from contaminating the incubators, to prevent chicks from falling to the bottom of the incubator, and to change temperature and humidity requirements between incubation and hatching. These changes are not necessarily required for hatching, but optimize the hatch for commercial companies. With home incubators, temperatures should be regulated for at least 2 to 3 days before the eggs are placed. During incubation, the temperature should be checked twice daily (fluctuations between 98° F [36.7° C] and 101° F [38.3° C] are fine for chicken eggs, but temperature requirements for other species should be researched before incubation) and the water pan kept full. Eggs (except dark shelled) should be candled at least once during incubation. Candling consists of shining a light through the egg to determine embryo viability by detecting movement of the embryo and presence of blood vessels. Dead eggs can then be removed before possibly exploding. Eggs need to be turned approximately four times a day until the last few days before hatch (embryonation Day 18 for chicken eggs). If eggs do not hatch, examination of the dead embryos can yield some clues to the cause. Common problems with the hatch include (1) early deaths (infertile eggs, too long or improper storage of eggs prior to incubation, and extreme temperature fluctuation), (2) late deaths but not pipped (extreme temperature fluctuation and poor humidity), (3) pipped but dried and stuck to the egg shell (generally poor humidity in late incubation and hatching period, and can also be due to weakened embryos from temperature fluctuations), and (4) pipped but drowned in egg fluids or malpositioned embryos (turning malfunction during incubation). 6 Once chicks are hatched, they should not be moved until dry and fluffed (Figure 15-3) . Occasionally chicks will hatch that have not completely absorbed their yolk sac and/or intestines. These chicks should be euthanized. Euthanizing newly hatched chicks to 10 days of age can be accomplished by cervical dislocation. One practical method is to take a scissors handle (ones that close completely opposed to each other), place directly behind the skull, and squeeze together to cervically dislocate. Embryonated eggs are best euthanized by chilling (as discussed in Chapter 22) . If possible, all chicken chicks should be vaccinated for Marek's disease within 24 hours post hatch (see Disease Prevention and Control). If chicks are obtained from an outside source, efforts should be made to receive them as soon as possible after hatch (unless they are raised at the hatchery). Chicks can withstand a period of 24 to 48 hours post hatch without food or water if they are kept warm. Longer periods will result in weakened and immunocompromised birds. Chickens acquired from the hatchery should be vaccinated for Marek's disease and, for all species, it is recommended to inquire about which vaccinations the hens have received (chicks get their antibodies from the hens via the yolk). This information can be important when making decisions in some flock management situations. Chicks need to be shipped without feed or water and in a container labeled prominently "do not feed or water," because they can drown in very small amounts of liquid. For commercial flocks, chicks and poults are sexed at hatch by manual inspection of the vent or feathering. As the birds grow, it is difficult to determine sex until secondary sex characteristics become apparent. In some strains, sex can be visually determined by using sex-linked traits such as color or feathering. Two common varieties are the black sex link and the red sex link. Blacks are a cross between a Rhode Island Red or New Hampshire rooster and a Barred Rock hen. Black sex-linked males have white natal down on their heads, whereas hens do not. Red sex links are a cross between a Rhode Island Red or New Hampshire rooster and a White Rock, Silver Laced Wyandotte, Rhode Island White, or Delaware hen. Red sex-linked hens have red natal down, whereas the males are white/yellow. With adult birds, the phallus can be observed by eversion of the vent (all that is needed in waterfowl where the organ is easily visible) and manual stimulation (chickens and turkeys). Male chickens and turkeys do not have an actual phallus but have two dorsal papillae that can be observed after eversion of the vent. 7 All young poultry need a source of heat until fully feathered. 8, 9 The least expensive option is to arrange a screen-covered heat lamp so that the distance from floor to lamp is 18 inches (45.72 cm) to 2 1 ⁄2 feet (76.2 cm) depending on the lamp wattage. The lamp should be red rather than white to discourage cannibalism in older chicks. Floor temperature should be approximately 100° F (37.8° C) directly under the lamp. A round, 1-to 2-foot-high (30.4 to 60.1 cm) brooder ring is placed under the lamp to keep chicks from straying too far from the heat source ( Figure 15-4) . It is unwise to use a square enclosure because some species will pile in corners and suffocate or suffer from hypothermia. This ring can be removed after the first week. The best rule of thumb for achieving the proper temperature is observing the distribution of the chicks at rest under the lamp. Chicks should be in an even and fanned pattern outward from the lamp. If they are piled under the lamp, the temperature is too cold; if they are pressed against the brooder ring, the temperature is too hot. Most young poultry species need some introduction to feed and water. If the flock size is large, about 25% of the flock can have "formal instruction" and those can be counted on to "teach" the rest. Instruction consists of dipping the beak into the water and then the feed. The appearance of the shiny drop of water and/or feed on the beak will also encourage exploration of these new objects by other chicks. It is best to place the feed into egg trays or flat low-sided dishes for the first week. Chicks continually peck at objects around their toes and will become familiar with the feed by this method. Feeding trays can be kept in the ring at the same time, and they will learn to eat from these gradually. Feeder trays are covered to keep the older chicks from scratching out feed and wasting it. In addition, older birds need feeders and waterers raised from ground level to be approximately equal to the thoracic inlet to help prevent fecal contamination. Waterers must have a small lip for the chicks to drink from, and it should be smaller if the species has tiny chicks. Generally waterers are bell shaped, allowing water from the center holder to refill the lip as needed. Water sources that are big enough for the chicks to fall into should be avoided. Newly hatched chicks are unstable on their feet and have trouble righting themselves if flipped over. This can result in mass drowning if waterers consist of open dishes. If this is a concern, placing brightly colored marbles or stones in the waterers reduces the depth of the water and the possibility of entrapment. Gradually, the feeders and waterers can be replaced with larger units to accommodate the growing birds. The number of different feed types can be overwhelming for the novice, and veterinarians should familiarize themselves with what is available in their area. 9 Generally, feed falls into three growth-related categories: starter, finisher, or meat builder and laying/breeding ration. It is extremely important to buy the right feed for the right growth stage, particularly for breeder/layer hens. When in doubt, it is best to choose a name brand feed supplied in a labeled bag. When purchasing bulk feed from a feed mill or farm store, it is recommended to see the label (or nutrient list) from the feed mix and/or obtain a copy. Often problems occur when inexperienced store clerks sell feed that is different from what the consumer expects. Scratch or single-source feeds (corn only) are not advisable unless used only as a supplement to the complete feed. Birds will preferentially eat the scratch, so it should not be offered until the nutritionally balanced feed is consumed. Laying birds must have calcium supplementation and layer ration. Another feed option is medicated feed. This is a general term used to describe feeds that have either anticoccidials or antibiotics added or both. For pet poultry, the addition of anticoccidials is recommended because of the prevalence of coccidiosis in backyard flocks. Feed containing antibiotics will need to be prescribed by a veterinarian, but these additives can be useful in situations where posthatch mortality is high from bacterial infections. Management changes during the adult stage need to address adequacy of housing and feed adjustment, as described earlier. For laying hens, nest boxes that are just large enough to fit one "seated" hen are desirable ( Figure 15 -5). 6 If eggs are to be collected only for consumption, then efforts need to be made to curb broodiness in the hens. The term "broody" refers to a hen that stops laying eggs to sit on the eggs, even when there are none in the nest box. As soon as this behavior is noticed, the hen should be moved to a wire cage. Broody hens can be aggressive, so caution must be taken during handling. Most hens treated this way will recover from their broodiness in 2 to 3 days. Without intervention, hens may remain broody for 3 to 4 weeks. Broodiness is breed dependent, with Silkies having the highest incidence ( Figure 15 -6). Artificial lighting will increase the number of eggs laid during the winter months, but will not increase the total number of eggs laid by the hen. 10 Light schedules for laying hens are usually 13-hour days or lights are kept on all night. Supplemented lighting will increase the risk of cannibalism in birds that are not individually caged. In general, light is progressively decreased throughout the growing period and is changed to a progressive increase at sexual maturity. The average targets for the start of increased lighting are 20 weeks for layer pullets and 23 weeks for meat pullets. These can vary depending on the season and the breed. Commercial chickens used for tableegg production are kept in lay for approximately 1 year and then are usually force molted. Broiler breeders rarely are kept in production longer than 44 weeks (layer breeders generally 52 weeks). Pullets used for table-egg production are usually caged and those used for production of hatching eggs are usually floor maintained with nest box access. Breeder pullets must be taught to use the nest box to prevent floor eggs. In commercial laying operations, hens are force molted by reducing light and providing low nutrition feed to bring the whole flock into molt at the same time. 10 This way commercial farmers provide a needed rest for the birds and can concurrently be sure that all hens are fed appropriately. Often backyard flocks will undergo a 3-to 4-month or longer molt period. As long as feather loss is not associated with ectoparasite infestation, reddened or abraded skin, poor nutrition, or open wounds, an "unusual molt" can be assumed for lengthy or bizarre-appearing feather loss ( Figure 15-7) . All hens need to be molted after approximately a year in lay. Hens need this rest period to rebuild calcium and energy stores. If hens do not molt naturally, then reduction of light will usually stimulate them to do so. If desired, this is also the time period that hens can be culled from the flock. In general, even the best hens will only approach about 70% of their former production level in their subsequent production period. Chickens that are fed xanthophyll-containing feeds will continually blanch (skin, shanks, and beak) throughout lay. The vent in a laying hen will be larger, moist, and pliable compared with a small, hard, and puckered vent in a nonlayer. The easiest way to determine lay on farm is to palpate the pubic bones. The bones in a nonlayer almost meet just below the vent, whereas the layer will have a "2 to 3 finger spread." The comb and wattles will be large, smooth, and firm in a layer and shriveled in nonlayers. When a hen lays an egg, her vent will evert to allow passage of the egg without contamination by feces. Once the egg is laid, her vent will usually return to the normal position quickly. Most backyard flock clients will be satisfied with random, natural mating in their flocks. With chickens and turkeys, the phallus does not actually penetrate the vagina; rather, the female cloaca everts exposing the vaginal opening and the male deposits the semen at the opening via gravity. If specific breeding is needed for breed maintenance, artificial insemination can be used. Turkey breeders virtually require artificial insemination because their size makes natural mating difficult. Artificial insemination is also used by many meat chicken primary breeders. The male is stimulated either by rubbing the back at the base of the tail and gently squeezing behind the tail or by massaging the soft part of the abdomen toward the vent. Semen quantity will be approximately 0.75 mL from the rooster and a little less from the tom. The semen needs to be used immediately because semen storage does not maintain adequate quality for most avian species. The National Poultry Improvement Plan (NPIP) is a voluntary cooperative plan involving State and Federal governments and the poultry industry. 11 It was started in 1935 to coordinate State control of Salmonella pullorum and it is aimed at reducing/eliminating predominantly vertically transmitted diseases in breeder flocks. Since its inception, the incidence of S. pullorum and Salmonella gallinarum has been significantly reduced. States may require that chickens/turkeys entering the state be from NPIP participants, or be proven free of certain diseases. NPIP is primarily aimed at preventing vertically transmitted diseases, but it does have a provision for monitoring low pathogenicity avian influenza (LPAI). The plan is administered by the United States Department of Agriculture (USDA) Animal and Plant Health Inspection Service and "Official State Agencies" (usually the poultry association in the State or the State Veterinarian). Producers sign onto state participation plans and the rules are outlined in the #9CFR Sections 145 and 147. Producers with farms in multiple states can establish cooperative agreements between the states. Backyard poultry owners who have breeding birds can become NPIP participants through Section E for exhibition birds. In addition to providing assurances of a commitment to health and disease prevention to customers purchasing chicks or eggs, NPIP is an amazing source of information on biosecurity, disease prevention, maintenance of flock health, and management. Pecking or cannibalism is one of the most frustrating and difficult problems to control in floor-reared birds. Certain species such as pheasants and quail are notorious for cannibalism, often leading to the use of individual cages as the only housing option. Even within a species, certain breeds can be more aggressive than others. Cannibalism usually does not begin in earnest under 2 to 3 weeks of age. If observed in young chicks, it is generally the result of insufficient feed or diarrhea (soiled vents can be attractive pecking sites). In older birds, methods of controlling pecking and cannibalism include reduction of lighting, reduction of bird density, increased numbers of feeders, and trimming the beaks. If a bird has been pecked, spraying the affected area with pruning tar (used for trees) is a good, practical at-home solution. The tar protects the skinless area from fluid loss, is nontoxic even when used on open wounds, and has the advantage of "identifying" the perpetrators by staining their beaks black. Pruning tar can be used for large areas as long as the deeper body cavities have not been penetrated. More severe wounds may be treated with a variety of bandages, appropriate pain management, supportive care, and surgical closure. If small numbers of birds are the aggressors, these birds can be given red spectacles that attach to their nares or be fitted with red contact lenses (available at most poultry supply stores). This is the most common "disease" condition of pet poultry and includes predator injury, entrapment of limbs in cages or other equipment, cannibalism, crushing injuries (e.g., stepped on, trapped in doors), and self-trauma (from spurs, beak, and nails). Most adult poultry are highly resilient and seem to recover from extensive injuries. Supportive therapy that can be accomplished at home includes providing warmth (via brooder lamp), providing adequate hydration (powdered milk at half-concentration provides extra protein), and force-feeding warm molasses-sweetened feed. If a pet bird owner is force-feeding, he should select a soft, flexible feeding tube and place it into the esophagus just past the laryngeal opening. Since most poultry have a crop, the food will enter the crop first, allowing for a slower filling of the proventriculus. The tube should not be forced because lacerations of the cervical esophagus or crop and subsequent fungal/yeast infections can result ( Figure 15-8) . Aspiration and regurgitation are also risks associated with forcefeeding procedures. Wounds that are not penetrating into the respiratory or abdominal cavities can typically be treated with topicals and basic wound care and management procedures. Parenteral antibiotics may not be required for treatment of many wounds. Most poultry will show evidence of recovery in 2 to 3 days. After this period of time, the prognosis for full recovery is generally poor, without more intensive veterinary care. Bumblefoot is an inflammatory condition of the foot characterized by swelling, ulceration, and erythema. 12 It is commonly localized to the plantar metatarsal pad or plantar digital pads. Primary foot trauma at the weight-bearing aspects of the foot is followed by secondary bacterial infections (Figure 15-9) . Staphylococcus sp. and Escherichia coli are the more commonly identified infectants. Heavy-bodied species are at the greatest risk, and trauma can be from puncture (direct inoculation) or from pressure necrosis. There is no age predisposition for bumblefoot, but common contributors to the condition include poor perch design, untrimmed claws, hypovitaminosis A, and poor weight management of birds. The epidermis is thicker in areas of pressure and plantar scabs inhibit healing and cause pressure ischemia. Heterophils can ingest Staphylococcus, but the enzymatic degradation is not efficient because of their lack of a specific lysozyme and dependence on other enzymes to kill bacteria. Acute infections are more often associated with caseous necrosis rather than purulent and liquefied exudate. Soaking the foot in magnesium sulfate (Epsom salts) twice a day for 10 minutes can help remove the scabs. Topical antibacterials and bandaging are usually sufficient for most poultry. Appropriate analgesia should be a part of most treatment regimes. Pressure and weight-deferring bandages can add great benefit by functionally removing any further pressure on the lesions as they are treated and given time to heal. There is a direct venous return from the foot to the kidney in birds and oral antibiotics may be needed to prevent systemic infection. The prognosis for successful treatment declines when there is osteomyelitis. Although all laying birds retain more fat in their livers than nonlayers or males, this condition is characterized by extreme fat deposition, sudden drop in egg production, and increased mortality. 7 The hens are often obese, have pale combs, and wattles and combs may be covered with dandruff. The etiology is thought to be a combination of fatty feed consumption and decreased exercise. Birds that are kept as house pets and are fed table scraps are at high risk for this condition. Mortality is a result of liver rupture and hemorrhaging with large blood clots found in the abdomen on postmortem examination ( Figure 15-10) . Treatment is by prevention-most backyard birds have adequate access to exercise but diet needs to be controlled. Lipotropic agents and dietary supplements (alfalfa, wheat bran, fish meal, dried brewer's yeast, soybean mill feed, vitamin E, and torula yeast) have been used with sporadic results. Caged-layer fatigue is similar to milk fever in mammals. 7 It is common in chickens, coturnix quail, and khaki Campbell ducks. Birds are unable to stand and have brittle bones. The ribs are often caved in or fractured at the junction of the sternal and vertebral components. Paralyzed birds are alert and responsive unless dehydrated from inability to access water. The probable causes are vitamin D 3 , calcium, and phosphorus deficiencies and/or imbalances. Birds may die acutely (often from fractured spinal vertebrae and severed spinal cords) or can rapidly recover (4 to 7 days) after placement on the floor with easy access to food and water. With backyard poultry, treatment with intramuscular vitamin D 3 or intravenous calcium gluconate can be helpful. Where indicated, appropriate analgesia should be a part of the treatment plan. Oyster shell can be added to the diet ad libitum to prevent this condition. The oyster shell must not be ground so small that it passes through the intestinal tract because it needs to be retained in the gizzard. The strain of bird and type of housing also affect the incidence of the condition. The key is to ensure good nutrition (and good cortical bone formation) prior to onset of lay. However, increased calcium in the diet for too long prior to production can result in urolithiasis and/or a permanent cessation of parathyroid gland activity. Normally the vent will prolapse during delivery of the egg. However, slow retraction due to obesity or in poorly developed hens (those that came into lay too early) will attract cannibalism, trauma, and edema formation, which will often prevent retraction. 7 Normally, these chickens are culled and prevention is practiced by controlling obesity, stocking density of cages, lighting, precocious onset of lay, and proper beak trimming. For pet poultry, stopping lay (reduced light and sharp reduction in feed), isolation, and keeping the vent clean until retracted will sometimes be effective in mild cases. In more severe cases of cloacal prolapse, medical and surgical options may be pursued. If chicks are hatched in the fall, an increase of light in the early spring can induce them to come into lay when they are physically immature, predisposing those young hens to prolapse. Controlling light is extremely important in this circumstance. Again, this is seen most commonly in pullets that are brought into production too early or in hens that are obese. 7 Ranges of this condition can be from a temporary binding observed in pullets that lay large eggs to complete obstruction of the oviduct. There can be eggs in the abdominal cavity (refluxed); single or multiple eggs in the oviduct; or shell membranes, shells, and yolk/albumin concretions in the oviduct. Egg binding and dystocia can be seen concurrently with other reproductive tract disease. The impaction can generally be identified upon abdominal palpation, ultrasound, and/or radiographic examination. Commercial hens are culled. Medical and surgical management methods vary from the conservative provision of warmth and massaging the abdomen, to using analgesia, parenteral fluids, manual obstetrical delivery methods, salpingotomy, and salpingohysterectomy ( Figure 15-11) . After removal of the oviduct, other reproductive problems can be seen because the hypothalamic-pituitary-gonadal axis remains intact. Internally ovulated ova may be absorbed or can lead to egg-yolk coelomitis. Cystic ovarian disease may be seen and ovarian neoplasia still can ultimately be encountered. Some salpingohysterectomized hens will assume male characteristics (crowing, aggression, and spurs) after surgery and these birds are called pollards. Losses from disease can be reduced substantially if good biosecurity practices are followed. 13 The biggest single source of pathogen entry is the introduction of other birds both from the same species and from different species. No person or animal should be allowed to visit the flock if they have recently been around other birds. Frequent transgressors are domestic animals (dogs and cats) and rodents. These animals can mechanically transmit disease or function as biological vectors. Attractants that bring animals to the area where birds are housed need to be removed. Feed must be kept in rodentproof containers and spilled feed rapidly cleaned up. Carcasses should be removed immediately and disposed of appropriately (local regulations are important). If burial is chosen, carcasses can be covered with lime to reduce the likelihood of being dug up by animals or exploding out of the ground during the summer. Good rodenticide and insecticide programs, including monthly rotation of chemicals, are essential. Waterers and feeders must be cleaned daily and disinfected at least every 2 to 3 days and houses should be cleaned when litter becomes moist. Store feed in containers that are not exposed to the sun, which can cause condensation when the containers cool at night, resulting in subsequent mold growth. Use feed rapidly and store no more than a 1-week supply. Foot pans filled with a dilute iodine solution or diluted bleach can reduce the risk of carrying in infectious organisms on boots. When the iodinated water becomes clear, it needs to be replaced. Bleach water needs to be changed every 24 hours. All equipment must be thoroughly cleaned and disinfected before use. Organic matter left on equipment can render even the best disinfectant useless. Again, species should not be mixed and, in best conditions, ages should not be mixed as well. All birds leaving the premises and encountering other birds (i.e., shows) and newly purchased birds should be quarantined for 6 weeks in a separate facility. Be sure not to use medicated feed during quarantine. Any equipment used at shows such as cages, feeders, waterers, and egg flats needs to be disinfected before storage or reuse. Be sure to check and service quarantined birds last. Birds should never be purchased from auctions or sale barns. These birds are often sold because of "deficiencies," and they are housed with numerous other species, increasing the potential for infectious disease. Ideally, birds are purchased from a reputable supplier and preferably NPIP certified. A visit to the farm of origin, prior to purchase, can be helpful. NPIP breeders can be found through the USDA website http://poultryimprovement.org/statesContent.cfm. A good source of information is your state's poultry association. Most pet poultry, unless used for show, rarely encounter the same intensity of disease exposure as commercial poultry. Many "disease" conditions are actually the result of environmental or feed mismanagement or are unusual presentations of normal events (molt). Vaccinations, with a few exceptions, are unnecessary for resident birds and can be difficult to obtain in the proper dose size. Most vaccines are sold in bottles of 500 to 10,000 doses and mixing errors can be devastating. In addition, waterborne and foodborne medication is also frequently tailored for commercial flock sizes and dilution errors for small flocks are common. Be sure to document all In general, when using medications off-label, the dosage recommendations for cats work well for poultry. Poultry are considered food animals even when they are pets, and medications banned for use in food animals (e.g., enrofloxacin) must not be used in backyard poultry, even off-label. The following list of diseases is not meant to be comprehensive, but includes some of the more common conditions that are encountered in backyard poultry practice. As in other species, the common poultry parasites are mites, lice, ticks, worms, and protozoa. Some parasites can present a public health concern and/or be transmissible to other food animals and pets (bed bugs). Regular monthly examinations by owners for external parasites are recommended. Parasites, both internal and external, can also be carriers of other disease agents. Two common mites of poultry are the northern fowl mite (Ornithonyssus sylviarum) and the red mite (Dermanyssus gallinae). 14 The northern fowl mite lives on its host and is most commonly found around the vent, tail, and breast of the bird (Figure 15-12) . They are easily observed and are a reddish brown color. The red mite does not live on its host and only feeds at night, making daytime diagnosis difficult. They can be found in cracks and seams near the bedding areas and appear as white fuzz balls or salt-and-pepper-like deposits. Red mites will cause feather loss, irritation, and anemia. Insecticides are available over the counter (OTC) in both powder and spray application for treatment of both mites. Do not use carbaryl powder (Sevin) either on the bird or on the premises. Either oral or injectable (200 mg/kg) ivermectin may be used off-label. Treatment with ivermectin should be monthly for at least 3 months even if mites are not observed. In flocks with a chronic or persistent problem with mites, monthly preventive treatment with OTC insecticides is recommended. Be sure to rotate the type of insecticide used to prevent resistance. Although poultry mites prefer to feed on poultry, they can move onto humans and will bite if trapped by tight clothing or other binding objects such as casts. There are several species of lice that live on poultry and lice or nits can be observed at the base of the feathers (see Figure 15 -12). 14 With severe infestations, growth and egg production can be affected because the birds will become anemic. The previously mentioned insecticides used for mites are available for treatment and the same prevention methods for mites can be used for lice. Lice are obligate parasites of poultry and will not transfer to other species for any length of time. Fowl ticks comprise a group of soft ticks that parasitize many species of poultry and wild birds. 14 Ticks are easily missed because they spend relatively little time on the bird. Heavy infestations can cause anemia or tick paralysis and ticks can be vectors for Borrelia anserina (spirochetosis) among other diseases. Spraying of buildings with insecticide (not Sevin) is the treatment of choice. Chlorpyrifos, pyrethroids, or chlorpyrifos and dichlorvos combined can be used for houses that are not occupied. Professional pest control may be needed for frequently infested flocks. Bed bug (Cimex lectularius) infestation of commercial poultry houses is a sporadic condition but is of concern both because of public health aspects and difficulty in controlling the problem. 14, 15 Bed bugs are reddish brown and approximately the size of ticks. Heavy infestations can cause a reduction in egg production, cloacal irritation, feather loss, and anemia. As with ticks, relatively little time is spent on the bird. Treatment of the house can be as described for ticks but pyrethroids generally do not work well for bed bugs. As with ticks, professional pest control treatment may be required. Large roundworms and tapeworms are the most common poultry worms and are generally the result of soil contamination and poor management. 16 Unless infestations are heavy, clinical disease is usually not evident (Figure 15-13 ). Piperazine can be used for roundworms and dibutyltin dilaurate for tapes. Do not use these compounds in laying hens. Resistance to piperazine is common, and fenbendazole (10 to 50 mg/kg) may be used off-label and needs to be repeated 7 to 10 days later. Piperazine may stun tapeworms without killing them and whole, live worms may be found in the litter. Proper litter management will reduce parasite loads and reinfection. Yearly fecal examination is recommended to ascertain the endoparasite status of flocks. Control of coccidia is one of the more costly problems of raising commercial and backyard poultry. 17 Coccidia are found primarily in the intestinal tract of most poultry, but occur in the kidney in geese. Coccidiosis is generally observed in young birds between the ages of 1 and 4 months. Birds under 1 week of age do not have chymotrypsin and bile salts for breaking apart oocysts and are not susceptible to disease. Coccidia are species specific. The disease causes diarrhea that is often bloody and frequently leads to death if not treated. Lesions in the intestinal tract vary with the species of coccidia involved, but the same treatment/preventive regimens can be used. Coccidia thrive in moist, heavily soiled litter and disease is often a result of too high a population density of birds. The kind of crowded housing found more often in winter months is an example of when population density may increase from acceptable to excessive. Poultry yards should be rototilled monthly after treatment with dilute bleach or lime to reduce oocysts available to birds. Prevention can be obtained by supplying coccidiostats in the feed. Coccidiostats are not included in organic feed, and these flocks must be monitored closely for coccidia. Outbreaks of disease can be treated with amprolium or with sulfadimethoxine (Albon) off-label. Sulfa drugs should not be used in laying hens. Amprolium has a very narrow margin for error and overdoses can lead to hemorrhagic diathesis and death. Vaccines are available but are generally only used in commercial birds in ovo or at hatch. It is recommended to submit a pooled fecal sample once a year for routine parasite screening and more often for problem flocks. The disease caused by Histomonas meleagridis is commonly known as blackhead and was first described in turkeys in 1895. 17 When it was determined that a milder form occurred in chickens who became carriers, the poultry producers stopped rearing turkeys on land previously used for chickens. The chicken cecal worm, Heterakis gallinarum, and earthworms are accessory hosts. Turkeys become infected by eating infected Heterakis eggs or earthworms containing juvenile heterakids. Direct transmission through feces is uncommon because of low survivability of histomonads when unprotected by Heterakis eggs. Losses are greatest in turkeys (especially under 3 months of age) but Histomonas can infect chickens, pheasants, chukars, ruffed grouse, peafowl, guinea fowl, bobwhite quail, and pheasants. The natural incubation period is 7 to 12 days and mortality in turkeys can approach 100% and morbidity is 80% to 90%. Recovered birds may continue to harbor histomonads in their ceca. Affected turkeys have sulfur-colored feces; depressed, drooping wings; and a stilted gait. Although the disease is called blackhead, not all turkeys will have a cyanotic head. Chickens often have an unapparent infection without sulfur-colored feces but can have blood in the feces. Leukocytosis, decreased uric acid and hemoglobin, transient rise in blood sugar, and increased aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) are usually seen. The gross lesions are primarily in the ceca and liver. Lesions in the ceca include enlargement, thickened hyperemic walls, caseous luminal cores, and ulceration of the mucosa. Lesions in the liver commonly have circular, depressed areas of necrosis circumscribed by a raised ring (targets). Diagnosis is generally based on clinical signs and gross lesions. Demonstration of histomonads in ceca from freshly killed birds is difficult because the histomonads die quickly and are harder to identify. The best prevention is not to place turkeys on ranges inhabited previously by chickens or other game birds and to control earthworms. Range rotation is not practical as histomonads have tremendous survivability in heterakid eggs (4 years or more). There are no vaccinations or treatments available in the United States, since the use of imidazoles has been banned in all foodproducing animals. Marek's disease (MD) is a common viral disease of chickens caused by a herpesvirus. MD is one of the top two diseases (along with coccidia) found in backyard chickens in the United States The primary lesions are tumors of the viscera, muscle, skin, and peripheral nerves. 18 Nerve lesions can be an early indicator of the disease resulting in a condition termed range paralysis. Birds with visceral tumors will often have only cachexia as a clinical sign. Tumors of the muscles and skin are frequently palpable. In a small percentage of birds, tumors of the iris can be observed antemortem, producing a grayish discoloration to the iris. Backyard chickens often present with enlarged crops from paralysis of the vagus nerve. Secondary impactions with ingesta are not uncommon, and, as such, MD should remain on the differential diagnosis when treating crop impactions. The crop can be manually or surgically emptied, but the prognosis is grave as morbidity caused by MD ultimately equals mortality (Figure 15-14) . The virus is shed by the feather follicles and therefore is found in feathers and dander. In this form, MD virus is quite hardy and can last for many months, making control by disinfection and biosecurity difficult. MD cannot be treated, but is preventable by vaccination at hatch. The vaccine is either applied via the in ovo route (at the hatchery) or subcutaneous in the skin of the neck after hatch. The vaccine cannot be overdosed even if all 1000 doses were applied to one bird, making it safe for clients to apply. The efficacy of vaccinations applied to birds older than 1 to 2 weeks of age is unknown. Vaccination does not prevent infection or shedding of the virulent virus but it prevents clinical disease. Clinical MD typically affects birds between 4 and 14 weeks of age; however, it is not uncommon in older birds. Outbreaks with high mortality are generally seen in younger birds, and older birds will usually succumb sporadically and often subsequently to an immunosuppressive event. If tumors are found in the viscera of deceased birds, carcasses should be submitted to a diagnostic laboratory for differential diagnosis between MD and another common lymphoid tumor disease, avian leukosis. Avian leukosis is more often found in birds older than 14 weeks and tumors are very similar to those found with MD. Avian leukosis also has no treatment or vaccination but is only a sporadic problem in backyard flocks. If MD virus is diagnosed in a flock of mature birds, depopulation is not necessary as mortality is generally sporadic. However, all incoming birds must be vaccinated, regardless of age. Infectious bronchitis virus (IBV) causes a rapidly spreading respiratory disease in young chicks. 19 Laying hens experience reduced production, egg shell abnormalities, and decreased internal egg quality. Certain strains of IBV will also cause kidney disease. The disease is caused by a coronavirus and IBV can be easily killed by disinfectants as long as it is not in organic matter. Chicks that are infected early in life may have permanent damage to the oviduct, which will prevent them from laying eggs (false layers). Although IBV is highly transmissible, most birds will recover with supportive treatment including increased housing temperature and half-normal concentration of powdered milk instead of water. Antibiotics can be applied to the water to prevent secondary infection. Vaccines are available; however, backyard chickens are usually not vaccinated unless they come in contact with other chickens (neighbors and shows). Live vaccines are applied in the water, by spray or via eye drops, and killed vaccines are applied intramuscularly. Newcastle disease virus (NDV) affects numerous species of birds and was the reason quarantine regulations for birds entering the United States were established. 20 Both velogenic (exotic) NDV and highly pathogenic avian influenza (HPAI) are on the United States select agent list, making them a national security concern. Exotic ND is highly fatal and does not exist in the United States at this time. However, in any incidence of acute mortality involving large numbers of birds or more than 50% of the flock over a 24-to 48-hour period, velogenic NDV and HPAI must be considered. Outbreaks in the United States have occurred in the past, resulting in the slaughter of thousands of birds and export bans. Birds with NDV die acutely with no gross lesions. Common lesions for both HPAI and velogenic NDV include blue discoloration of the shanks, wattles, and comb; skin hemorrhages; torticollis; ataxia; and piling. NDV does exist in milder forms in the United States, and they are primarily characterized by respiratory disease and a drop in egg production. Mortality is variable and depends upon the strain of the virus. As with IBV, vaccination is available (same routes of application) but is generally only given to pet poultry exposed to other birds. Vaccination is not used for prevention of exotic NDV but for prevention of infection by pathogenic endemic strains. Fowl poxvirus causes nodular lesions primarily on the unfeathered portions of the bird (Figure 15-15 ). 21 Occasionally, it can cause lesions in the mouth and trachea, causing death from suffocation (wet form). Once the bird recovers from the disease, immunity is generally lifelong. Not all pox outbreaks are caused by fowl poxvirus; they can be caused by related strains such as turkey pox, psittacine pox, and quail pox. Strains are somewhat species specific but can occasionally affect other species. One strain may not cross-protect with another. Vaccination is available and should be applied to flocks on premises with a previous history of pox or with presence of pox in nearby birds. The poxvirus vaccine is not attenuated, but is applied in a location that pox does not occur. For this reason, it is important to follow the label directions for vaccine application. The most common application is using a "stab stick," which is dipped into the vaccine and then passed through the wing web. The cups in the two sticks deposit the vaccine into the thin tissue of the wing web. Approximately 7 to 10 days post vaccination the area is checked for two small bumps at the inoculation site called "takes." With turkeys and other birds that sleep with their heads under their wings, the vaccine should be applied to the drumstick after parting the feathers. Turkeys can actually get pox infection of the head transferred from the vaccine takes, which is the reason for the alternate location for application. Poxvirus is transmitted through contact of infected lesions with open wounds and by insect bites (mosquitoes). Elimination of standing water and other mosquito sources is important for prevention. Preventing cannibalism during an outbreak and keeping Avian encephalomyelitis (AE) occurs in chickens, turkeys, pheasants, and quail and primarily affects young chicks 1 to 3 weeks old. 22 Nearly all commercial flocks are infected, but clinical disease is low due to the passage of maternal antibodies. AE can be transmitted vertically in eggs laid between 5 and 13 days post infection, and it is an enteric infection under natural conditions. The spread is more rapid in floorraised birds than in cage-raised birds. Clinical signs include central nervous system deficits such as spinning, seizure-like activity, and torticollis. Mortality can be 50% or more and recovered chicks may be permanently blind in one or both eyes. Chicks hatched from recovered birds may also have blindness for unknown reasons, so keeping recovered birds for breeding is not recommended. There is no treatment. Vaccination of the breeders (both chicken and turkey) provides maternal antibodies for the young that are critical for prevention of infection. Since many specialty breeders, particularly those that sell stock to feed stores or other secondary distributers, do not vaccinate, AE is a fairly common viral disease in backyard birds. Vaccination should be given after 8 weeks of age but by at least 4 weeks prior to production. The vaccine can be co-applied with the pox vaccine using the stab-stick method. Avian influenza (AI) is worldwide in distribution and occurs in multiple species. 23 Migratory waterfowl yield the most viruses but disease is primarily in chickens and turkeys. Waterfowl can shed for long periods and often do not have detectable seroconversion whereas chickens and turkeys generally stop shedding after seroconversion. Transmission occurs via the respiratory tract and feces, and the incubation period is from a few hours to 3 days. Influenza is caused by an orthomyxovirus with three antigenically distinct types: A, B, and C. It is typed by the antigenic nature of the nucleoprotein and matrix antigens. Type A is classified into subtypes based upon the hemagglutination and neuraminidase types and B and C occur only in humans. The standard nomenclature is name 5 type of host (except human), geographic origin, strain number, year of isolation, and hemagglutinin-neuraminidase (HN) category. As with velogenic NDV, HPAI should be considered in any cases of acute mortality involving many birds. However, screening for LPAI is of national importance for HPAI prevention in both commercial and backyard flocks. The NPIP has an LPAI program and individual states often have monitoring programs for both resident and imported birds. Testing is done either by a direct antigen test or polymerase chain reaction (PCR) on swabs from the choanal cleft (gallinaceous birds) or cloaca (waterfowl) or an agar gel immunodiffusion test conducted on either serum or egg fluid. Serology and direct antigen tests are generally used for screening and PCR is used for confirmation. Flocks positive by screening tests must have samples sent to an accredited laboratory for PCR confirmation. If it is H7 or H5, the samples are sent by the laboratory to the National Veterinary Services Laboratories (NVSL). All flocks confirmed positive for either LPAI or HPAI will be depopulated. No vaccination for AI is permitted in the United States without permission from the USDA. There are many different species in the bacterial genus of Salmonella, not all of which carry the same pathogenicity. 24, 25 Generally speaking, S. pullorum and S. gallinarum cause the greatest problem for poultry while Salmonella typhimurium and Salmonella enteritidis (SE) are important from a public health aspect. S. pullorum is egg transmitted and causes a diarrheal disease in young chicks and poults resulting in high mortality. Adult birds are asymptomatic carriers. Diagnosis is based upon disease history and isolation of the bacteria. Prevention is achieved by purchasing birds from disease-free flocks. Treatment is not recommended because it can cause birds to become carriers. Fowl typhoid (S. gallinarum) occurs in chickens and turkeys and many other game and wild birds. Fowl typhoid is similar in disease presentation and diagnosis to pullorum, although mature birds can show clinical signs of fowl typhoid. Prevention is again achieved by obtaining disease-free stock (NPIP certified). As with LPAI, small flock owners can participate in NPIP and have birds tested for pullorum/typhoid (PT) for show and breeding purposes. PT testing can be conducted by certified trained individuals or veterinarians, and consists of taking a small blood drop from the wing vein and conducting a plate agglutination test right on the farm (Figure 15-16) . Commercial PT antigen and equipment are available for purchase by the public, and the USDA provides a training DVD (Figure 15-17) . Any birds that test positive by the plate test must have serum tested by an accredited veterinary diagnostic laboratory for confirmation. Clinical signs are infrequently observed in poultry infected with SE and S. typhimurium. Flocks can be monitored by obtaining egg samples and environmental samples for culturing the organism. In the United States, owners of Colibacillosis is caused by the organism E. coli and is usually secondary to other infections such as IBV and mycoplasmosis. 26 A wide variety of clinical signs, both respiratory and enteric, can be observed and the organism occurs in most species and age groups. Vigorous adherence to biosecurity and sanitation programs will effectively prevent the organism from causing disease. Many antibiotics can be used for treatment and sensitivity to the antibiotic should be obtained. Treatment is usually successful if the disease is caught in the early stages. Chronic respiratory disease in poultry (primarily chickens and turkeys) is generally caused by Mycoplasma gallisepticum (MG) infection. 27 Pathogenicity of the organism is enhanced by infection with other organisms. Clinical signs of respiratory disease develop slowly in a flock, and feed consumption drops (Figure 15-18) . Infection of the sinuses is common in turkeys. Since there are no certified MG-clean noncommercial breeders, it is crucial that clients only purchase birds from a reputable supplier or to visit the farm before purchase to be sure the birds are free of respiratory diseases. Serology, PCR, and isolation and identification of the organism can be used for diagnosis. An on-farm plate test, similar to that for PT, is available for screening purposes. Both live and killed vaccines are available, but the use of live vaccines may need State or Provincial approval. Killed vaccines can be effective for preventing/reducing clinical signs but will not prevent the birds from transmitting the disease vertically or horizontally. Depopulation and restocking is advised for breeding flocks. Treatment is expensive and the disease often recurs after cessation of treatment. Either injectable or feed/water-based Tylosin is the best approved treatment. It can be used for up to 1 month but egg and meat withdrawal times must be observed. MG is a reportable disease in turkeys in some states and provinces, and depopulation may be required. Other important mycoplasmas in poultry include Mycoplasma synoviae (infectious synovitis) and Mycoplasma meleagridis (venereal infection and airsacculitis), but are not commonly seen in backyard poultry. In the 1850s it was discovered that fowl cholera (FC) could be transmitted both by cohabitation of infected birds with naive birds and via inoculation. 28 This discovery stimulated the first attempts to prevent the disease. FC is one of the four diseases for which the veterinary division of the USDA was created. It is more prevalent in the late summer, fall, and winter and occurs both sporadically and enzootically. FC is primarily a problem in chickens, turkeys, ducks, and geese but it is probable that all types of birds are susceptible. Turkeys are the most severely affected and it is most common in young mature birds, but all ages are susceptible. Mortality is variable but can approach 80% or more depending upon the virulence of the strain and the environmental conditions (in turkeys). Laying chickens are more commonly affected than broilers because of their older age; chickens less than 16 weeks old are very resistant. FC occurs primarily in ducks over 4 weeks of age and mortality ranges up to 50%. P. multocida from avian species will kill rabbits and mice, but other mammals are fairly resistant to clinical signs. Chronically infected birds are the major sources of infection and birds are essentially infected for life. There is no relationship between FC and human cholera but humans can transmit FC to poultry or become infected from poultry via excretions from the nose or mouth. Clinical signs of FC include both acute and chronic forms. The acute form is very rapid and signs may only be present for a few hours before death including fever, anorexia, ruffled feathers, mucous discharge from the beak, diarrhea, increased respiratory rate, and cyanosis just prior to death. Geese may just die acutely with no premonitory signs. The chronic form can occur following an acute stage or be from low-virulence organisms. It consists of localized infections whose site(s) determine the type of clinical signs, which include swollen wattles, sinuses, joints, foot pads, and sternal bursae; exudative conjunctivitis and pharyngitis; torticollis; tracheal rales; dyspnea; and roup and bloody discharge from the beak. P. multocida can be isolated from viscera of acutely infected birds and from lesions from chronic cases, and the bacteria can be tentatively identified by observing bipolar organisms in liver imprints stained with Wright's stain. The organism is gram-negative on Gram stains. For live birds, the nasal cleft can be swabbed. Serology is primarily used to evaluate efficacy of vaccination. Antibiotics have variable success depending on the sensitivity of the strain and the duration of the disease before treatment. Sulfonamides are only bacteriostatic and usually cannot be used to cure localized abscesses or the effect of toxins. Sulfamethazine doses are 0.5% to 1% in food or 0.1% in the water for at least 5 days and often the FC will recur after treatment is discontinued. Streptomycin, penicillin, and chlortetracycline administered intramuscularly can also be used. If tetracyclines are used, the addition of citric acid to the drinking water and reduction of calcium use will increase the efficacy of the antibiotic. Biosecurity is very important especially since this is not a disease of the hatchery. There are vaccinations including both live and killed products, but these would be only advisable for flocks with a history of FC or at risk for FC in their immediate area and the causative serotypes need to be ascertained to select the best vaccine. Mycobacterium avium and Mycobacterium intracellulare are called M. avium complex (MAC), which affects both mammals (miniature schnauzers, Siamese cats, Bassett hounds, various ruminants [deer], pigs, and rabbits) and birds. 29 Food animals and rarely humans are infected with an M. avium subsp. Paratuberculosis, which causes an infectious inflammatory bowel disease. Mycobacteriosis in chickens was first recognized as a separate disease around 1884 but is seldom observed in commercial poultry. It is more common in small flock operations that maintain older chickens and in game birds. Mycobacterial disease has a prolonged clinical course with high total morbidity and mortality. MAC in birds is a chronic wasting disease and is a World Organization for Animal Health (OIE) list B disease. All species of birds are susceptible but it is rare in turkeys. Mycobacteriosis usually occurs after 3 weeks of age and clinical signs include biliverdinuria, lameness, and diarrhea. The liver and spleen are enlarged grossly and may rupture. In addition, granulomas are seen in the spleen, liver, intestine, and rarely lungs. Transmission is from ingestion of materials contaminated with bird feces, which contain large numbers of bacilli. Mycobacterium persists in the environment for long periods. Importation of live poultry into countries free of MAC may require tuberculum testing. There is no treatment because of the associated public health aspects, and depopulation and destruction of equipment and housing through burning and application of cresylic compounds to the ground is advised. Brooder pneumonia occurs in many poultry and nonpoultry species of birds. 30 Birds under 3 weeks of age are most commonly affected and infection is obtained from hatchers or brooders that are contaminated with fungal spores. Older birds can be chronically affected and lesions can occur in virtually any tissue. Voice changes and ocular infection are common in chronic infections. Morbidity is variable and mortality can be high in clinically affected birds. Gross lesions include white caseous nodules scattered throughout lungs, air sacs, trachea, tongue, syrinx, and bronchi, and the nodules eventually become yellow or green (fungal mats) and caseated. Aspergillosis is generally observed in birds that are already immunosuppressed for other reasons. Antibody responses to infection are not well defined because of difficulty with testing methods. Antemortem diagnosis is often difficult because of nonspecific clinical signs. Culturing of the fungus, demonstration of typical fungal hyphae, or PCR from fresh preparations from lesions is used for diagnosis. Prevention is obtained by thoroughly cleaning hatchers, incubators, waterers, feeders, and ventilation fans and keeping litter clean and dry. Alternating wet and dry conditions encourage fungal growth. Treatment is expensive and may not be effective. Ketoconazole has been used with variable success, and itraconazole and voriconazole offer greater success as the systemic component of a treatment strategy. For prevention of spread within a flock, a 1:2000 aqueous solution of copper sulfate is provided in place of drinking water and the ground can be sprayed with either nystatin or copper sulfate. The essential mechanism of action for all mycotoxins is interference with protein synthesis and destruction of rapidly dividing cells. 31 The target organs can vary among the different mycotoxins. There is no treatment and identification of the mycotoxin and removal of the source is crucial. Where there is concern for the potential for foodborne mycotoxicosis, for every new batch of feed used, a small Ziploc bag sample should be held back for possible future testing. Aflatoxin includes aflatoxins B1, B2, G1, and G2. Aflatoxin B1 is most common in grains but all are toxic and carcinogenic. Aflatoxin primarily affects the liver and can be found in virtually all kinds of feed and many types of litter. Clinical signs include decreased appetite and growth, decreased carcass pigmentation, abnormal crying, picking at feathers, purple discoloration of legs and feet, lameness, ataxia, convulsions, death, decreased semen volume, and decreased hatchability of eggs. The major gross lesions are enlarged and pale liver and kidneys. In chronic cases, the liver may be shrunken and the gallbladder enlarged. Ergotism is caused by Claviceps in cereal grains (rye) and is the oldest known mycotoxin. Mold in the feed replaces grain with a hard black mass called an ergot. Ergotism killed thousands in the middle ages (St. Anthony's fire) and it produces alkaloids. Toxins affect the nervous, vascular (vasoconstriction and resultant gangrene), and endocrine systems. Clinical signs include decreased food intake and growth; necrosis of beak, comb, and toes; distorted feather development; and enteritis. Ergotism primarily affects leghorns and other laying breeds and only trace amounts remain in the meat. Trichothecenes have both caustic and radiomimetic effects and are primarily caused by Fusarium. They were first observed in Russia in the early twentieth century. Overwintering of grains in the field promoted mold growth and caused "alimentary toxic aleukia" with morbidity and mortality often greater than 50%. Trichothecenes are found in numerous feedstuffs and usually cause feed refusal. Clinical signs include necrosis of oral mucosa and skin, acute gastrointestinal signs, severe depression, and skin lesions on feet and legs. Necrosis of oral mucosa, reddening of gastrointestinal mucosa, mottled liver, distended gallbladder, visceral hemorrhages, and splenic atrophy are the most common gross lesions. The bone marrow is altered and there is a decrease in egg production. Birds generally recover when given new feed. Nutrition is the process of furnishing cells inside the animal with that portion of the external environment for optimum functioning of the many metabolic chemical reactions. 32 It involves procurement, ingestion, digestion, and absorption. Water is also considered an important "nutrient." Poor nutrition can result from inappropriate diet for the bird type, lack of important nutrients, inability to ingest or digest the offered food, and loss of nutrients in the feed from improper storage, among other causes. It is extremely important to have a trustworthy and reliable source of feed. Since backyard flocks are such small consumers of feed, often large feed mills will sell their lower quality feed for noncommercial flocks. In addition, feed mills dedicated to specialty food animal herds or flocks may be mixing different feeds on the same day and residual ingredients can be problematic. Be sure always to save a copy of the feed label for later examination. Water intake should be double the feed intake. Drop in water intake may be observed 24 hours before other clinical signs in a flock. Dehydration can be identified by increased skin turgidity and shriveled shanks. Some of the causes of dehydration are prolonged hatch, prolonged shipping time, dry brooders, drinkers at the wrong height or water pressure, and water refusal. Vitamin A is associated with depleted feed corn due to improper storage, no alfalfa added to the feed, or hatchlings from vitamin A-deficient hens. Xerophthalmia (dry eye), anorexia, retarded growth, and ataxia are usually observed from 1 to 7 weeks of age. Chicks often die before xerophthalmia develops. Gross lesions include pustules in the upper gastrointestinal tract, exudate in the conjunctiva and nasal cavity, opaque and dry cornea, scales surrounding the choanal cleft, and hyperkeratosis of the plantar surfaces. Feed samples should have 5000 IU/lb, liver samples 60 to 300 ppm, and serum 0.3 to 1.7 ppm of vitamin A. Treatment consists of water-dispersible vitamin A. Rickets is the term used for younger birds and osteomalacia for mature birds. In poultry, the etiology is a deficiency or imbalance of calcium, phosphorus, and vitamin D 3 . Lesions include a soft and pliable beak, claws, and keel; beading of the ribs; enlarged epiphysis; fractures of the long bones and spine; and enlarged parathyroid glands. Vitamin D 3 deficiency can be treated with three times the normal levels of vitamin D 3 provided in the feed or liquid vitamin D 3 in the water for 2 to 3 weeks. Calcium and phosphorus levels need to be adjusted for the species, breed, reproduction status, and age levels of the birds. The etiology of this condition is vitamin E/selenium deficiency and most commonly occurs in chickens, quail, turkeys, and ducks. Gross lesions include subcutaneous green-tinged fluid and pale streaks in the skeletal muscles, gizzard, and heart; degeneration of the skeletal muscle and cardiac muscle; and pancreatic acinar necrosis. Encephalomalacia can be prevented by providing synthetic antioxidants in the feed but there is no treatment. Muscular dystrophy can be treated by adding cysteine to the feed and exudative diathesis is treated by adding selenium to the feed. For individual birds, a single oral dose of 300 IU of vitamin E is effective. It is crucial to know what drugs are banned for use in food animals versus those that are not labeled for poultry. Pet, show, and backyard poultry are still considered food animals by the FDA. There are few drugs labeled for use for hens in lay. Most commercial poultry veterinarians will be able to give advice concerning drug withdrawal times and approved drugs. For information contact aaap.info or the local State or Provincial Veterinarian. The Avian Disease Manual (aaap.info) has Reproduction in poultry Use of thermography to screen for subclinical bumblefoot in poultry Wakenell PS: Biosecurity, cleaning and disinfection, California egg quality assurance plan External parasites and poultry pests What to do about bed bugs in poultry houses Internal parasites Protozoal infections Marek's disease Infectious bronchitis Newcastle disease Saif YM, Fadly AM, et al Avian encephalomyelitis Saif YM, Fadly AM, et al Pullorum disease and fowl typhoid Saif YM, Fadly AM, et al Saif YM, Fadly AM, et al Mycoplasma gallisepticum infection Fowl Cholera Saif YM, Fadly AM, et al Fungal Infections Saif YM, Fadly AM, et al Nutritional Disease Backyard Poultry and Pigeon Houses Building chicken coops Breeds of poultry and their characteristics A guide to better hatching Commercial chicken production manual Obstetrics and reproduction of backyard poultry Storey's guide to raising poultry Scott's nutrition of the chicken Note: Prior to use, seek specific guidance on egg and meat withdrawal times.