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Cow Autopsies Have Been Revealing – for Sep. 6, 2010

Veterinarians, especially here in Alberta, have a unique opportunity when it comes to BSE testing. That’s because the testing procedure mandates a full-fledged autopsy of the animal if the cause of death is unknown.

An autopsy is a useful tool for helping a producer solve a problem, especially if an improvement in management could eliminate deaths. In the past we seldom got the opportunity to post-mortem cows unless several died in close succession.

The BSE program changed that. I have already discussed the possibility with our provincial veterinarians that if surveillance for other diseases were necessary it would be easy to gather samples at the same time. This has become a win-win-win situation between veterinarians and their clients and the federal/provincial BSE program.

Monitoring tests such as ear notching for BVD or sampling the small intestine for Johne’s disease would be two examples of the kind of surveillance sampling that can be done. These types of tests would give us a good indication of the disease incidence over a large geographic area or the entire province. It provides valuable information as to the disease status in specifiherds as well.

The results I am finding with these gross post-mortems on suspect animals have really surprised me. This article will outline the common preventable conditions being found as well as some possible management changes necessary to correct them.

We often diagnose peritonitis or more specifically traumatic reticuloperitonitis (hardware disease) and treat the herd for it accordingly. In several herds I have found it in more than one autopsy. These have generally been younger cows just reaching their peak production. In these cases the follow-up involves trying to discover how sharp bits of metal are getting into the cows.

Magnets can be added to the feed wagons or inserted individually into all the breeding heifers. Not that all metal is attracted to magnets.

Aluminum, brass and sharp hard plastic not picked up by magnets are just some of the materials that can also cause hardware disease.

You can eliminate some of these cases by keeping your pastures clean and ensuring that field machinery such as silage cutters have metal detectors and/or magnets on them. For every single case we diagnose through an autopsy there are likely several sub-clinical cases in the herd showing reduced production in the form of decreased growth or milk production.

Bloat from being cast is also a far more common cause of death than I ever imagined. In every case I have come across I have not found a potent feed in the rumen. Bloat is caused when a ruminant is unable to eructate, or burp, the rumen gases (methane) as it is produced. When close-to-calving cows become rollypoly there is less room available for expansion of the rumen. It is surprising how little of an incline is necessary to get the legs elevated above the body making it difficult for the cow to rise. When she goes down for an extended period, either calving or aborting, the rumen may get quite large and bloat is always a possibility.

Try to avoid, if at all possible, these slightly sloped areas coming off the bedding pack. I realize the odd time there is nothing that can be done, but keep these concerns about slope in the back of your mind. It would also help if we avoided excessively fat cattle.

At our clinic, several autopsies revealed large abscesses on the liver, which if they had eaten into large blood vessels would have caused sudden death. Liver abscesses almost always indicate a feeding problem where an animal was brought onto feed too fast without the benefits of ionophores like Rumensin. Here we can explore the past history of the cow and if home raised examine the feeding history. Bringing cattle onto full feed gradually and using the help of ionophores can often eliminate liver abscesses.

It’s surprising how many apparently healthy cows die of bronchopneumonia (classic shipping fever). These seem to be individual cases, perhaps cows coming into heat or stressed from transport. When checking the calves in the spring also keep an eye on the cows for heavy breathing, lethargy or depression. They can be treated with antibiotics if caught early enough. Consult your veterinarian as to the recommended treatment for your herd.

When doing the autopsy have your veterinarian check the parasite status both by doing a fecal count and checking for lice, both biting and sucking, by examining the hair coat. This may point to further herd problems, which can be treated.

If mineral status is in question samples of the liver can be grabbed for analysis.

If the cow is open we check for the viability of the uterus and again samples can be taken for reproductive tests (at an additional cost to you).

Help your veterinarian to help you make the most out of the autopsy and give you suggestions to improve your herd’s health status.

Let’s get the most out of these subsidized autopsies. Remember animals decompose quickly in the summer heat so make the call as soon as the carcass is discovered. The fresher the tissues the better the chance of a diagnosis.

Dr. Lewis is a veterinarian with a large animal practice in Westlock, Alta.

About the author

Contributor

Roy Lewis is an Alberta-based veterinarian specializing in large-animal practice. He is also a part-time technical services vet for Merck Animal Health.

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