Published November, 2014

A necropsy is not something most horse owners contemplate until faced with the death of a horse. And upon losing an equine companion, most owners don't immediately think, "does my horse need a post-mortem exam?" While not all horses warrant a necropsy, in this article we will aim to educate horse owners before they are faced with an urgent need for information about necropsies.

The necropsy procedure is also referred to as a post-mortem examination (PME), or autopsy, though the latter is generally reserved for humans. A necropsy involves multiple procedures; the first step is a “gross examination” (what can be see without a microscope) of the inside and outside of the body. Prior to the gross exam, the examiner will read the case history, which should include details such as the length of illness, signs the animal displayed, any other animals affected, vaccination history, possible exposure to toxins, etc. Although the necropsy is a visual exam, it’s also a multisensory experience: Do tissues feel normal by palpation? Is there an unusual smell? Based on case history and gross observations, the examiner might choose to save tissues for microscopic examination and select further tests to run. For example, he or she might elect to carefully examine the spinal cord in a horse that could no longer stand, but not in a horse that had difficulty breathing. He or she might request bacterial cultures of the lung in a horse with clinical and/or gross evidence of pneumonia but not in a horse with suspected liver failure.

Microscopic examination (also referred to as histology) is conducted by a veterinarian who has undergone post-graduate residency training in pathology, similar to human medical pathologists. The examiner might find changes in organs that he or she did not observe grossly. If microscopic changes elucidate a process that went clinically or grossly undetected, the veterinarian might request other tests. For example, evidence of acute liver damage might warrant toxicologic testing for known liver toxins. The range of tests includes bacterial culture, virus isolation, fecal examination for parasites, serology (for detection of antibodies that indicate exposure to a disease-causing pathogen), molecular biology (for identification of pathogens that might be present in very low numbers), mineral analysis, and toxicologic analysis for specific toxins. The pathologist will consider all of these results to arrive at a diagnosis--a summary of the case--to report to the client.

The reasons most owners choose not to pursue a necropsy upon a horse's death include cost (particularly after a prolonged and expensive illness), the desire to retain the body for burial or cremation, and the lack of an available veterinary professional to perform the procedure. Necropsy costs range anywhere from $130-500 or more, depending on the lab and in-state/out-of-state status. Discuss your options with your veterinarian before ruling out a necropsy.

A few reasons to perform a necropsy include:

1. The most obvious is to determine the cause of death or the event leading up to the necessity for euthanasia. This is often for owner’s peace of mind, but is also commonly for insurance or legal documentation. It is difficult for all parties, including owners, managers, and veterinarians, to experience a death loss without an explanation. The primary goal of the necropsy is to answer: Why did this horse die?
2. Owners and veterinarians often desire further characterization or confirmation of a disease process that was diagnosed clinically. In some cases a second or predisposing condition is present that exacerbated the disease or made it difficult to treat. This information provided by the necropsy guides owners and veterinarians in future diagnostic and treatment decisions for their horses.
3. In horses that received treatment, veterinarians and owners often question whether the treatment had any effect, side effects, or unintended reactions. Reporting adverse reactions to treatments is vital to ensuring other horses are not harmed by similar therapy and practitioners to take steps to prevent adverse reactions when that treatment is required.
4. In some cases owners or veterinarians would like to answer questions about a condition the horse had that was unrelated to the cause of death such as mild recurrent colic, infertility, or lameness.
5. An extremely important reason, particularly in cases of sudden or multiple deaths, is to determine if other horses in the same herd or barn are at risk for contagious illness or death. A timely diagnosis can prevent future death losses.

Lynne Cassone, DVM, Dipl. ACVP, a diagnostic pathologist at the University of Kentucky Veterinary Diagnostic Laboratory, provided this information.