Veterinary Forensic Toxicology Investigations

Malicious Animal Poisonings

As noted earlier, the lack of a central agency for reporting animal poisonings makes determination of their frequency difficult. Add to that the fact that many toxicoses may be misidentified as natural disease, and the actual incidence of animal poisonings, both accidental and intentional, is not known. What little information is available on animal poisoning incidence generally comes from human and animal poison control centers (PCCs) who receive calls from animal owners and veterinarians regarding potential animal poisonings (Gwaltney-Brant, 2012). Assuming PCC data is a cross-section of all animal poisoning incidents, some generalities can be determined. Most reported animal poisonings are accidental in nature, with intentional or malicious poisonings making up less than 1/2 of 1% of all reported poisonings. Most single-animal poisonings involve companion animals, whereas most multiple-animal poisonings involve livestock. Dogs account for more than 75% of malicious poisoning cases, and cats are involved in ~15% of cases, with the remainder involving other species such as livestock and wildlife. Large breed (especially German shepherd dogs), intact male dogs of 2-4 years of age are at increased risk for malicious poisonings. More malicious poisonings are reported in the summer months, presumably because animals tend to be less closely confined and a variety of toxicants (e.g., rodenticides, pesticides) are readily available.

It is safe to say that the vast majority of malicious animal poisoners get away with their offenses. There are little data available regarding those who maliciously poison animals, and there are no good forensic profiles on animal poisoners (Gwaltney-Brant, 2016). Poisons make ideal weapons in that they are readily available, easily distributed, and difficult to trace to the source. One way to consider what type of person might be inclined to maliciously poison animals is to consider the various motives a person might have for doing so. Elimination of a perceived or real nuisance animal is likely at the top of the list of motives for malicious animal poisonings. Animals that make excessive noise, trespass, threaten humans and other animals, eliminate on or damage property of another, or injure livestock or other animals may become such an annoyance to trigger someone to take action. Indeed, it is not illegal to poison certain species universally accepted as threats to public health, such as mice and rats, so poisoning other species might be considered by some people to be a legitimate activity. Other malicious poisoners may act in order to retaliate against a particular animal and/or its caretaker; this has occurred in many livestock poisonings where the poisoners turned out to be disgruntled former employees. Would-be burglars might poison pets, watchdogs, or guard dogs in order to gain free access to protected property. Some people might poison an animal to gain some sort of control over its owner; this most commonly happens in situations involving domestic violence. Persons who are suicidal have poisoned their pets along with themselves. Some poisoners might derive a sort of pleasure over seeing an animal die from poison. Poisons have been involved in cases of Munchausen syndrome by proxy involving pets, whereby the pet caretaker (usually the owner) intentionally injures the pet in in order to gain sympathy and attention for themselves.

Forensic Investigations

Because the clinical syndrome produced by many poisons can mimic those caused by natural diseases, a toxicosis may not be initially suspected when dealing with ill or dead animals (Galey & Hall, 1990; Ensley, 1995). Conversely, when a toxicosis is suspected, it is important to consider whether other nontoxic diseases processes such as infectious disease, metabolic disease, neoplasia, and so on, may be involved instead. Determining the cause of an animal’s illness or death requires an open mind and sound investigative work. Historical information is a vital component of the investigation, as it can help identify potential risk factors in the patient’s background. When a poisoning is suspected, careful questioning of the animal’s caretakers is essential to get an idea of the animal’s husbandry, environment, and potential for exposure to toxicants. Questions about the patient should be asked such as basic signalment (species, breed, age, reproductive status, weight) and health history (e.g., vaccination status, prior health, current and past medications/supplements, etc.). For cases involving multiple animals, the number of animals at risk, number affected, and number of deaths should be determined. Time frames such as when the animal was last noted to be normal, gradual or sudden onset of clinical signs, and duration of signs should be documented. Also documented should be a list of signs that were noted (including any signs that have since resolved), the severity of signs, and any treatments administered by a caretaker or veterinarian (as well as response to treatment). The results of any diagnostic procedures (laboratory tests, diagnostic imaging, etc.) should also be obtained. If necessary, a trip to the animal’s environment (home, farm, zoo, etc.) should be made to investigate potential hazards (e.g., toxic plants, questionable feeds) that might not have come up in the initial questioning (Galey & Hall, 1990). Physical examination of the affected animal(s) along with necropsy of any dead animals should be undertaken, with thorough documentation of both normal and abnormal findings.