The Importance of a Post-Mortem Exam

J. L. Goelz, D.V.M.

SheepLetter, Vol.26, No.6, August 2006

When investigating flock health problems the Veterinarians at the Pipestone Veterinary Clinic often find that a post-mortem exam is more revealing than examining a live lamb. Flock problems can usually be ruled-in or out depending on the findings. Often the Veterinarian can determine the organ system involved which will gives us clues to which diseases are possible and likely. Generally the Veterinarian can also get a sense of the length of the disease process such as acute (sudden) or chronic (prolonged).

A basic post-mortem exam includes examining each accessible organ system for the presence or absence of lesions. A lesion is simply areas of the organs that are considered abnormal. Just as in examining a live animal, observing that something is abnormal is the first step to arriving at a diagnosis. While most producers turn up their nose at dissecting a dead lamb there is tremendous value in the carcass. The difficultly becomes determining what is normal post-mortem change and what is abnormal. This is the part where you Veterinarian can bring value. Your Veterinarian is trained to determine abnormalities in the carcass of dead sheep. If your Veterinarian cannot determine the actual cause of death or disease he/she will often submit samples to a veterinary diagnostic lab for further testing.

Many diseases can be rapidly confirmed with a quick post-mortem exam. The list includes: starvation/hypothermia, parasitism, Clostridia entertoxemia (Type C and D), Casseous Lymphadenitis, bloat, grain overload, copper toxicity, pneumonia, white muscle disease, ovine progressive pneumonia, salmonellosis, and many others. Generally a preliminary diagnosis can be made in a matter of minutes and flock treatment, if necessary, can begin immediately. If a diagnosis cannot immediately be made or if further testing is necessary at least the flock owner can have an idea of diseases that are ruled-out. In other words the absence of lesions can identify diseases that are unlikely and thus should not be a concern.

What can you do to help? First of all, inform your Veterinarian of the history of the sheep. Did it act sick prior to death? If you have had multiple sheep die is this animal similar or representative of the others? How much time elapsed between when you noticed the sheep as sick and when it died? How long has the sheep been dead? Next, having the carcass as fresh as possible is the most important aspect of having good results on the exam. Carcasses begin to decay immediately after death and the speed of decay is proportional to the outside temperature. A carcass that is two days old but in a 35 degree environment has good diagnostic value. Alternatively, a carcass that is 6 hours old in 90 degree weather is often to decomposed to drawn much information. If the carcass cannot be examined immediately find a way to keep it cool until it can be examined. During lambing season this may be throwing the dead lambs outside of the barn to keep them cool. During summer placing ice on the carcass and keeping it in the shade will slow the rate of decomposition of the carcass. If you can get the carcass to Veterinarian in reasonably good condition you may find out that in terms of flock health information, a dead sheep can be worth a lot.