A post-mortem helps to diagnose disease
Death is a touchy subject on farms.
No one likes losing animals, but a post-mortem examination (PM) can reveal vital information, not just in determining what the individual died of, but also to identify if a disease is affecting the whole group.
Many diseases can’t be diagnosed purely by examining the live animal.
Chronic weight loss in sheep can be caused by liver fluke, but also by several other diseases which are hard to diagnose. Some have severe consequences.
Without a PM, it is very difficult to differentiate fluke from OPA, a contagious tumour of the lungs, or Johne’s disease.
Fluke is easily treated and prevention is not difficult. However, undiagnosed OPA is a contagious disease, which can be devastating if left to run its course.
If lambs are scouring and dying, then a PM will identify the specific disease process, enabling a more targeted approach to treatment and prevention.
Coccidiosis treatment will have been wasted if lambs have actually got nematodirus or vice-versa.
Even when you know an animal has died of pneumonia, a PM can still be useful. Samples taken can confirm what caused the pneumonia and allow appropriate vaccination, antibiotic treatment or other preventative measures to be instigated.
With some diseases, such as liver fluke or lungworm, PMs can allow an instant diagnosis, and there are an increasing number of on-farm tests which can give instant results.
However, others may require tissue samples to be sent for further tests. Histopathology and PCR are very useful and can be turned around within a week.
It can be frustrating when a PM does not provide any answers so to increase your chances of success, choose a fresh carcase to submit, and ideally within 24 hours of death.
Ask your vet for advice, and choose a sick animal which best represents the problem you are having. For example, with calf pneumonia, select one showing signs which are most like the ones that have already died, and not a calf which has been scouring, when the others did not.
PMs can be done on-farm by your vet, or be sent to a VI centre or external vet at a fallen stock collection centre. All are useful and your vet can advise you on the best option.
Stephen Bradley, Vet