Toxicants Commonly Used in Intentional Animal Poisonings

Although there are literally thousands of potential poisons available for those who wish to maliciously poison animals, most poisoners aren’t terribly knowledgeable about poisons, and they tend to use what they know (Merck, 2013; Gwaltney-Brant, 2016). So, it’s not surprising that the most common poisons used in malicious animal poisonings are compounds that are fairly

298

Table 14.3 Toxicants associated with intentional poisoning of animals

Toxicant	Species Most Commonly Affected	Mechanism	Effects	Best Samples
Anticoagulant rodenticides (e.g., brodifacoum, bromadiolone, difethialone)	All	Interference with vitamin K recycling results in decreased formation of vitamin K-dependent coagulation factors	Uncontrolled hemorrhage, anemia	Liver (anticoagulant screen)
Acetaminophen	Dogs, cats	Toxic metabolites cause injury to liver and red blood cells	Vomiting, diarrhea, icterus, weakness, difficulty breathing, chocolatecolored gums	Plasma, serum, urine
Alcohols	Dogs	Cause central nervous system depression	Disorientation, vomiting, incoordination, coma, seizures	Blood, urine
Amphetamine, methamphetamine,	Dogs	Overstimulation of nervous and cardiovascular systems	Agitation, hyperactivity, heart arrhythmias, seizures	Blood, plasma, urine, stomach content
pseudoephedrine
Arsenic	Livestock	Damages capillaries, causes kidney damage	Acute collapse, anemia, hemorrhagic vomiting and/or diarrhea, kidney failure	Gastrointestinal contents, urine, liver, kidney
Blister beetle (Epicauta spp.)	Horses	Vesicant action in gastrointestinal and urinary tracts	Acute death, hemorrhage of epithelium of gastrointestinal tract, urinary tract	Urine, intestinal content, examination of hay for insect
Bromethalin rodenticide	Dogs, cats	Interference with cellular pumps in nervous system causing edema	Ascending paresis, paralysis, weakness, seizures, coma	Brain, adipose tissue, liver, kidney
Caffeine	Dogs	Overstimulation of nervous and cardiovascular systems	Agitation, hyperactivity, heart arrhythmias, seizures	Stomach content, serum
Cardiac glycoside-containing plants Oleander (Nerium oleander)	All	Alters cell membrane transport pumps, resulting in cell dysfunction	Vomiting, diarrhea, acute heart failure	Gastrointestinal contents
Foxglove (Digitalis spp.)
Cholecalciferol rodenticides	Dogs, cats	Causes elevated blood calcium levels, which result in mineralization of soft tissues	Increased thirst, increased urination, kidney failure	Kidney
Ethylene glycol	Dogs, cats	Initial alcohol effects, then kidney damage	Disorientation, vomiting, coma, seizures, kidney failure	Serum, kidney

Veterinary Forensic Toxicology

(Continued)

299

Table 14.3 (Continued) Toxicants associated with intentional poisoning of animals

Toxicant	Species Most Commonly Affected	Mechanism	Effects	Best Samples
Ionophores	Horses, dogs, occasionally other livestock	Damages heart and/or skeletal muscle (species specific)	Acute heart failure in horses, other livestock; weakness, paresis, paralysis in dogs	Stomach content, feed samples
Metaldehyde	Dogs	May alter nerve conduction	Tremors, seizures, hyperthermia	Stomach content, serum, liver, urine
Nicotine	Dogs	Overstimulation of nicotinic nerves early, then neuromuscular blockade	Agitation, hypersalivation, vomiting, diarrhea, tremors, seizures followed by weakness, progressive paralysis	Stomach contents, blood, urine, kidney, liver
Organochlorine insecticides	All	Overstimulation of nerve conduction	Tremors, seizures	Adipose tissue
Organophosphate and carbamate insecticides	All	Overstimulation of muscarinic and nicotinic nerve receptors	Hypersalivation, vomiting, excessive bronchial secretions, diarrhea, lacrimation, tremors, weakness, seizures	Brain, retina
Paraquat	Dogs	Damages cells in lung, resulting in progressive lung injury and fibrosis; corrosive	Oral, esophageal or gastric ulcers; progressive respiratory failure (over days to weeks)	Urine, lung
Red maple (Acer rubrum)	Horses	Damages red blood cells	Weakness, collapse, anemia, death; secondary kidney injury	Gastric contents
Selenium	All	Depletes cell metabolic enzymes resulting in acute cardiovascular collapse	Weakness, tetanic spasms, respiratory depression, heart failure	Blood, liver, kidney
Strychnine	Dogs, cats	Loss of inhibitory function in spinal cord results in uncontrollable muscle activity	Convulsions, respiratoryfailure	Stomach contents, liver, bile, kidney
White snakeroot (Ageratina altisimmia, formerly Eupatorium rugosum)	Livestock	Damages heart and skeletal muscle	Acute heart failure, weakness, death	Urine
Yew (Taxus spp.)	Horses, dogs	Damages heart muscle cells in horses; causes central nervous stimulation in dogs	Horses: Acute heart failure Dogs: Seizures	Gastric contents
Zinc phosphide rodenticide	All	Converts to corrosive and toxic phosphine gas	Restlessness, agitation, abdominal pain, tremors, seizures, coma	Serum, liver, kidney, pancreas

Veterinary Forensic Toxicology Investigations

Source: Gwaltney-Brant (2016)

widely known to be toxic, such as rodenticides and insecticides. More sophisticated poisoners might be aware of the toxicity of other compounds such as acetaminophen, caffeine, or nicotine. Most poisons used are compounds that are easily obtained and common in the environment; for companion animals, that might mean rodenticides, insecticides, snail killers, ethylene glycol, caffeine, nicotine, and human medications such as antidepressants or acetaminophen. Livestock poisonings commonly involve agricultural pesticides and fertilizers, rodenticides, and feed additives that are readily accessible in an agricultural setting. In attempts to collect on insurance, valuable horses have been intentionally poisoned with “natural” toxins such as blister beetles and yew plants in attempts to make the toxicosis appear accidental. There do seem to be some regional tendencies throughout the country, probably reflecting relative availability of the toxicants in these areas; for example, strychnine is a common malicious poison used in the U.S. Pacific Northwest, while aldicarb, a highly toxic carbamate insecticide, is often used in the southeastern United States (Gwaltney-Brant, 2012). A brief synopsis of some of the more commonly used toxicants to poison animals is listed in Table 14.3.