Certain situations surrounding the death of an animal may result in litigation either for the veterinarian or the client. Anesthetic deaths, previously healthy animals found dead, and suspected poisons are often very traumatic to owners who frequently demand answers. The sudden and unexpected death of a previously healthy pet while in the care of a veterinarian often raises the suspicion of malpractice in the mind of the owner. Owners may commission a necropsy from another veterinarian in hopes of confirming their suspicions. For previously healthy animals found dead around the home, owners may suspect poisoning or some other form of foul play and commission a necropsy to provide documentation for use in court against a neighbor. In these situations, it is prudent to have a necropsy done by a veterinary pathologist who, as a professional and objective third party, can answer as many questions as possible and ensure the final report is beyond reproach and will hold up in court.

Anesthetic deaths in previously healthy animals during the induction, maintenance, or emergence phases of general anesthesia are usually not related to an overdose of anesthesia, but rather to an unexpected reaction to the anesthesia. Idiopathic Anesthesia Reactions (IAR) is thought to be a cardiac hypersensitivity of some individuals when given the anesthetic at its accepted and standard dosage. Studies put incidences of IAR at around 1 in 400-800 anesthetic inductions. IAR has no detectable predisposing factors, does not appear to favor one breed or species over another, is not revealed during standard screening laboratory tests, and is thus impossible to predicted in advance. IAR causes no significant gross or microscopic changes aside from general, nonspecific evidence of heart failure. In diagnosing IAR at necropsy, it is imperative that all other conditions, particularly conditions that could cause heart failure, be eliminated. IAR remains an unfortunate, albeit very rare, risk of anesthetic induction in animals as well as humans.

In situations where a previously healthy animal is found dead, the owners always suspect poisoning, though this is rarely the case. Most of these cases often turn out to be one of the following rule-outs: anaphylaxis, bleed-out (ruptured tumors), intestinal malpositions (volvulus, intussusception), cardiomyopathy, electrocution (lightning or chewing on electric cords), physical trauma (moving vehicle, falls), small caliber gunshot, drowning, botulism, septicemia, heat stroke, or ingestion of poisonous plants. While some conditions may be obvious on necropsy, others require a good history and/or histopathology to arrive at the definitive diagnosis. Samples collected for histopathology should be placed promptly in 10% formalin to minimize autolytic change. Any tissue with gross lesions should be collected, as well as standard samples of lung, heart, liver, kidney, spleen, stomach, intestine, and brain.

Poisoning is one of the most difficult conditions to diagnosis on necropsy. While a few poisons produce lesions that are diagnostic during the gross necropsy or the subsequent microscopic exam (like warfarin and ethylene glycol), most produce no lesions, or at best nonspecific changes. Even when poisoning is suspected, veterinary toxicology has very few "screening tests" that cover a wide range of toxins. To make a diagnosis, the specific suspected toxin must be requested. In such cases, history of access to a potential toxin, as well as the clinical signs displayed prior to death, becomes very important in deciding which toxin to request. The tissues to be collected for toxicology testing may depend on the type of toxin suspected (i.e. fatty tissue in suspected hydrocarbon toxicity). Generally, however, stomach contents, blood, liver, kidney, and urine are the tissues most likely to contain a toxin owing to its ingestion, processing, and/or excretion. These tissues should be packaged separately, frozen immediately to prevent further the breakdown of the toxin, and never placed in formalin.

Like all medical procedures, necropsy has its limitations, and not "all the answers" as is commonly believed. It is very common for the necropsy findings to be inconclusive as to the cause of death or clinical syndrome. Some conditions are just not characterized by changes that can be detected either grossly or microscopically. This is often the case in poisoning. In addition, necropsy lesions cannot always be interpreted properly in a vacuum, without the benefit of the rest of the clinical picture. As with all medical procedures, the necropsy is often just another piece of the entire clinical puzzle.