It’s 6:30 on a February morning and you are lying awake, afraid to go outside. You’ve found three aborted fetuses in the past four days, and worry you may have a “wreck” on your hands.
No one in the cow/calf business escapes without having some experience with abortions. Some basic knowledge of the major causes can help you try to prevent this costly problem. When abortions do occur, you need a diagnostic plan in place to discover the cause as quickly and accurately as possible.
Bovine abortion is a common problem, and at low levels (one or two per cent of the herd) it is perfectly normal, albeit undesirable. Some may be caused by physical injury. Some losses may even be beneficial when the abortion is due to faulty genes which you do not want perpetuated in your herd. But we start to be concerned when more than two or three per cent of females abort their fetuses.
IBR and BVD viruses, various bacterial diseases such as leptospirosis, and fungi from moldy feed can cause infections in the dam which spread to the placenta and fetus and cause abortion. Venereal diseases (trichomonas and campylobacter) can also cause abortion, although they most often cause infertility and loss of the embryo early in pregnancy.
Cost-effective control measures, including vaccination, can dramatically lower risk. If you are not using a reproductive vaccination program for your herd, discuss one with your vet.
The idea that you can avoid disease, and abortion storms, by maintaining a “closed herd” is largely a pipe dream with the way cattle are mixed and moved today. Fences won’t keep out the disease.
Poor nutrition accounts for some abortions. Cows receiving inadequate protein or energy are at risk of aborting or having premature, weak calves. Feed testing and ration balancing, along with body-condition-scoring the cow herd, will help avoid these losses. Vitamins A and D also must be supplemented by feed or injection for proper development of the unborn calf. In many areas, vitamin E and selenium supplements are needed to avoid those abortions caused by nutritional muscular dystrophy (white muscle disease).
When confronted with an abortion, remember that the placenta is as important as the fetus in diagnosing the cause of an abortion. The laboratory has about a 30 to 35 per cent success rate in determining the cause, so it needs as many samples as possible.
Preserve all aborted fetuses, in case they are just the first of many. If we can get a fresh fetus, we will do an initial post-mortem and save tissue in formalin. These can be sent on to a lab later if abortions keep coming. If the fetus is found frozen, keep it frozen in a freezer or a snowbank morgue until you are sure it is an isolated case. Put the fetus and placenta in a plastic bag along with a tag noting the cow’s ID and the date you found the fetus. If more than a few abortions occur, send all fetuses and placentas to your local clinic or lab.
Some cows should be examined by your vet as they many show signs of the disease that is causing the outbreak. Blood samples, to check for antibodies, and a careful history should accompany lab submissions. Make a log of all vaccinations, along with history of other diseases in the herd, and a summary of the cow’s feeding program. If you do your homework, you should be able to sleep well on those cold February mornings.