Veterinarian’s Corner: Late-Term Abortion Diagnostic Work-Ups
For the purposes of this article, we are going to focus on late-term abortions, which are those that occur in the last three months of gestation. Early embryonic death, or repeat breeders, are diagnosed with different strategies because we do not have an aborted fetus or placenta for diagnostics.
Under what circumstances should you do an abortion work-up?
While most of us want to know why all abortions happen because they represent economic loss, doing a diagnostic work-up on every case is probably not cost-feasible and may not yield useable information. All farms have a normal baseline abortion rate of 3% to 5% of pregnancies. “Normal” abortions are caused by unknown events like congenital problems. If herd records show an increase in abortions over several weeks or months, this should trigger a diagnostic work-up. Also, if a group of cows all abort at the same time, a veterinarian should be involved immediately. Groups of abortions are commonly called abortion “storms.”
Work with your herd veterinarian to submit tissues for an abortion diagnostic work-up. The best tissues to send in are entire placentas and fetuses from an abortion. We all know how hard it can be to get these tissues. Sometimes the cow will eat the placenta (if the coyotes or dogs don’t get it first) or the fetus will get swept into the manure pit by the automatic barn cleaner. Frozen tissues are better than something that has been left in the sun for two days over the weekend – those are worthless. Depending on the case, we may ask for other samples like blood from the dam or feed samples.
What’s the primary information you’re trying to learn and how do you apply that to the management of your dairy herd?
The “best-case scenario” is that we find the cause of abortion from a pathogen or a toxicity that can be linked to the abortion(s) in the herd. The owner, with their veterinarian, can then implement management strategies to avoid further reproductive loss in the herd.
Negative test results are not always bad, however. They can rule out high-impact diseases or toxicities like BVDV infections or mycotoxins, therefore avoiding additional herd testing or control strategies that can be expensive.
Inconclusive testing from an aborted fetus or placenta can be frustrating. Commonly, the cause of an abortion – especially if it is a virus – is long gone by the time the dead fetus is actually expelled from the dam, and our pathologists usually only find overgrowths of normal bacteria, like Trueperella pyogenes. Working with the herd veterinarian and owner will likely lead us to different types of diagnostic testing to help solve the problem.
Remember, accurate herd records are critical links to solve abortion problems on farms. They are just as helpful as high-quality diagnostic testing and management tools, such as vaccines and feed additives.
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