key: cord-255139-hswef5ky
authors: Khan, Safdar A.
title: Differential Diagnosis of Common Acute Toxicologic Versus Nontoxicologic Illness
date: 2018-11-30
journal: Veterinary Clinics of North America: Small Animal Practice
DOI: 10.1016/j.cvsm.2018.07.003
sha: 
doc_id: 255139
cord_uid: hswef5ky

This article provides a display table laying out the differential diagnosis of common acute toxicologic versus nontoxicologic illnesses in small animals. Major clinical abnormalities are listed, along with common toxicologic rule outs and nontoxicologic rule outs. Further readings are also provided.

Safdar A. Khan, DVM, MS, PhD a,b, *

Upon presentation of an acutely ill animal, a veterinary professional must consider poisoning as a potential cause among the differentials. A complete and thorough case history in this regard is essential for differentiating a poisoning situation from a naturally occurring disease. Obtaining a clear recent history may sometimes be quite challenging, especially in situations where the pet was unsupervised before the initiation of clinical signs. History questions must include animal signalment (breed, sex, and age) and weight, previous medical history, vaccination history, type of feed used (brand; home-made or commercial) and any medications the pet is taking. Initial information about any other animals present in the household, timeline of clinical signs, types of clinical signs reported by the owner, number of affected animals, pet's environment (indoor vs. outdoor; fenced or free roaming), location (urban vs. rural), time of the year (summer vs. winter), recent renovations/ updates (construction material; lead in older farms/houses), recent visitors, availability of human medications in the pet's environment (antidepressants, pain killers, stimulants, nutritional supplements), presence or recent use of chemicals (insecticides, herbicides, rodenticides) in the house/yard, information about neighboring animals (outbreaks; illnesses; death) and information about indoor/outdoor plants may help provide clues to the clinician to narrow down the search for a possible cause for the pet's illness. A good case history can help speed up the process of narrowing down a potential cause; eliminate several unnecessary steps, save time, and money.

Before obtaining a complete case history, the first goal should be to stabilize the patient and preserve life of the acutely ill animal irrespective of the cause. Relying too much on specific antidotal treatment may be dangerous. A majority of clinical cases on presentation are treated supportively as only a very few specific antidotes are available or needed for treating specific poisonings. Therefore, on presentation, make sure the animal has a patent airway and adequate ventilation. Support and maintain cardiac functions. Monitor heart rate, rhythm, and blood pressure, and treat cardiac arrhythmias and blood pressure changes as needed. Hydration status, fluids, electrolytes, and acid-base balance should be checked and corrected accordingly. Treat central nervous system abnormalities (excitation, depression, seizures) as required, and maintain body temperature within the normal range (treat hypothermia or hyperthermia). After stabilizing the vital functions, obtain a history; then, provide other necessary treatment such as decontamination (administration of activated charcoal, gastric lavage, bathing, dilution), supportive care, and carrying out other diagnostics (complete blood count, chemistries, urinalysis, radiographs, ultrasound) as needed. Collect samples for toxicologic analyses if required. Toxicology testing performed in a diagnostic laboratory can be expensive and time consuming and mostly, results are not available immediately. Therefore, to rule in or out a suspected cause, first perform commonly used in-house diagnostics before ordering toxicology analysis. For example, monitoring prothrombin time or clotting times can be useful in anticoagulant poisoning cases. Other samples for toxicology testing in a diagnostic laboratory include whole blood for heavy metal analysis (lead), blood cholinesterases (organophosphate poisoning), and presence of pesticides (anticoagulant rodenticides). Similarly serum/plasma can be used for some metal analysis (zinc), drugs, alkaloids, and electrolytes (useful in sodium chloride poisoning or water intoxication). Stomach contents (vomitus; freeze upon collection) can be used for detecting pesticides, metals, baits, alkaloids, and drugs. Urine (chilled or frozen) can be used for some metal analysis, drugs and their metabolites, and alkaloids (strychnine). Table 1 outlines some important toxicologic versus nontoxicologic rule-outs based on clinical abnormalities one must consider in an acutely ill animal. Where necessary, with each rule-out, along with major clinical abnormality, a brief description of other clinical signs is also provided. An acutely ill animal with sudden onset of clinical effects may often have multiple major clinical signs/abnormalities present. The purpose here is to provide an initial guideline for considering toxicologic versus nontoxicologic rule-out. Once a reasonable etiology has been narrowed down or established, the reader is encouraged to review a more detailed discussion on management of the particular poisoning or disease listed in this reference (see Table 1 ). 

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2,4-D, Dichlorophenoxyacetic acid; AKI, acute kidney injury; ALT, alanine aminotransferase; aPTT, activated partial thromboplastin time; CKD, chronic kidney disease; CNS, central nervous system; CV, cardiovascular; FeLV, feline leukemia virus; FIV, feline immunodeficiency virus; GI, gastrointestinal; NPK, nitrogen, phosphorus, potassium; NSAID, nonsteroidal antiinflammatory drug; PCV, packed cell volume; PT, prothrombin time; RBC, red blood cell; SLUD, salivation, lacrimation, urination, defecation.