When an animal dies, producers often simply have it disposed of.
But that often means valuable information is lost — so decisions for the rest of the herd or altering treatments for subsequent cases cannot be made. An experienced veterinarian can glean very valuable information from a complete autopsy and often give you the cause of death immediately.
A post-mortem is relatively quick to do and allows the internal organs to be directly viewed. This takes the guesswork out of any diagnosis. The tissues can be cut open and touched for texture, and relative size of the organs assessed. All these clues help in the definitive diagnosis.
The poultry and swine industries have incorporated post-mortems as a major part of their preventive medicine protocols. With cattle, an experienced veterinarian can usually make a definitive diagnosis on an autopsy. Cattle and bison, especially in their abdomens, have the ability to wall off infection making the site fairly obvious to the trained eye. If the exact cause of death can be determined the main questions to be asked are:
1) Is this an individual problem (in which case there are no worries for the rest of the herd)?
2) If a transmissible disease, what can be done as a preventive for the rest of the herd?
3) How long has the disease been progressing and does it suggest the condition was missed for a time? (Suggestions can be given to watching for certain clinical signs on subsequent cases.)
4) If the problem was rightly diagnosed and treatment was initiated, what was the reason for the treatment failure?
5) Were two or more disease entities happening at the same time?
Producers in my experience are often distraught and often want reassurance as to whether they missed any clinical signs and whether the death could have been prevented. Sudden deaths are extremely important to post-mortem since no clinical signs were evident. Several serious diseases such as blackleg (clostridial diseases in general), anthrax, and plant poisonings have sudden death as the only presenting complaint. Keep in mind most animals bloat up somewhat after death.
Any post-mortems for insurance reports should be documented with a complete identification of the animal and, in some instances, digital photos may be very valuable. Some farm insurance policies do cover acts of God (such as death resulting from lightning or drowning), but a veterinary examination will be necessary. Auction markets carry insurance, so most unexplained deaths are autopsied — primarily to find out when the problem started, and if an injury during transport or at the facility can be ruled out or not.
In order to help the veterinarian, the carcass needs to be preserved as much as possible. On a hot summer day it only takes a few hours to start to decompose. Until the veterinarian can arrive, keep it covered in a cool location and make sure predators such as coyotes don’t ravage it. The opposite occurs in the winter where fresh carcasses make the diagnosis easier. Freezing has a tendency to disrupt the tissues — however, it is a far superior storage method than allowing the carcass to rot. Bison producers must remember autopsies on this species is almost an emergency. Their hide is so thick I have seen mature cows autolize (decompose) just from sitting overnight.
As well as determining the cause of death, post-mortems also allow the monitoring of other herd parameters such as parasite burdens or nutritional status. Samples of the liver can be sent to a lab to check for some trace mineral analysis such as copper, iron or zinc.
Years ago, a lot of provincial labs would perform complete post-mortems. This service has since been phased out and it is now common that local veterinarians perform the autopsies and take tissue samples for histo (microscopic analysis). It’s now common for private labs to do a culture, and if bacteria are the cause recommend the best choices of antibiotics. This can give an effective option to the farmer with outbreaks such as pneumonia and are especially important with AMR (antimicrobial resistance) being of concern. Other specific tests called PCR tests determine the causative organism and this can provide valuable information so treatments could be tailored for future cases or changes made to the preventive vaccination program.
Veterinarians can also preserve the necessary tissues at the clinic in the event another similar case comes along. Commonly abortions can be handled this way. Tissues can be saved and sent in if a higher-than-normal abortion rate starts to develop.
Use your veterinarian for most deaths on your farm (they can be autopsied on farm or at most large-animal clinics). This can go a long way towards preventing other disease situations in the future. Most cases can be quickly diagnosed and preventive steps can be initiated immediately if needed.
There is a lot to be learned from autopsies and that knowledge will help your veterinarian further enhance the health and productivity of your herd. The dead cattle may identify a contagious condition or it could be specific to that animal and these are the important things post-mortems illustrate for us. If a diagnosis is made, a specific course of action can be taken which renders the rest of your herd healthier. New graduate veterinarians are highly trained in pathology or have excellent labs to send tissues to if the initial diagnosis is hard to make. Please have your veterinarian do post-mortems, but get them done in a timely manner.