Often producers, when an animal dies, simply have it disposed of. Often 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 much valuable information from a complete autopsy.
A postmortem is relatively quick to do and all the internal organs can be directly viewed. This takes the guesswork out of any diagnosis. The tissues can be cut open 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 postmortems as a huge part of determining their preventative medicine protocols. With cattle most times an experienced veterinarian can make a definitive diagnosis. It is often not as difficult as the CSI television program series would lead you to believe. 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:
Is this an individual animal problem in which case there are no worries for the rest of the herd?
If a transmissible disease, what can be done as a preventative for the rest of the herd?
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)
If treatment was initiated and against the right cause what was the reason for the treatment failure.
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 postmortem since no clinical signs were observed. Several serious diseases such as blackleg, anthrax and plant poisonings have sudden death as their only presenting complaint. Keep in mind all animals bloat up somewhat after death but that is not the cause of death.
Any postmortems 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 lightning or drowning, but a veterinary examination will be necessary. Auction markets carry insurance so most unexplained deaths are autopsied to primarily find out when the problem started. Injuries during transport or at the facility can be ruled in or out.
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 for decomposition to start. 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 autopsy’s on this species is almost an emergency. Their hide is so thick I’ve seen mature cows autolize (decompose) just from sitting overnight.
As well as determining the cause of death postmortems also allow the monitoring of other herd parameters such as parasite burdens or nutritional status. Samples of the liver can often be sent to a lab to check for some trace mineral analysis such as copper, iron or zinc.
Years ago many provincial labs would perform complete postmortems. This service has since been phased out and now commonly local veterinarians perform the autopsies and if necessary extra tissues can be taken for histo (microscopic analysis).
A culture and sensitivity analysis can be performed by most private labs to help determine if bacteria are the cause of death and the best choices of antibiotics to be used. This can provide producers with an effective treatment option with outbreaks such as pneumonia.
Veterinarians can also preserve the necessary tissues at the clinic in the event other similar cases crop up. Commonly abortions can be handled this way where tissues can be saved and sent if a higher-than-normal abortion rate starts to develop.
Use your veterinarian for most deaths on your farm. This can go a long way towards preventing other disease situations in the future. Most cases can be quickly diagnosed and steps at prevention if necessary can be initiated immediately. In some provinces autopsies on mature animals (greater than 30 months are covered under the BSE programs). What an ideal opportunity to find an exact cause of death. This information may lead to ways to alter your management practices to prevent further cases or allow you to rest easy knowing it was an individual case.
Roy Lewis is a practising Large Animal Veterinarian at the Westlock Veterinary Center, north of Edmonton, AB. His main interests are bovine reproduction and herd health.