This is my first column with The Western Producer and I hope that I can follow in the shoes of Jeff Grognet and Roy Lewis, who have so capably written about practical animal health issues in this spot for many years. My “day job” consists of working at the Western College of Veterinary Medicine for the last 19 years as a beef cattle clinician and faculty member. I enjoy teaching the great veterinary students we have at WCVM and getting to work with cattle producers and veterinarians from across Western Canada.
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It’s that time of year when it isn’t unusual for cow-calf producers to notice the occasional cow that is obviously in heat after being confirmed pregnant, or a cow with a bloody discharge that has obviously aborted.
It is common to have a small percentage of cows lose their pregnancy prematurely, but the underlying concern is that this may be the first of many.
One of the most disheartening events that can occur on a cow-calf operation is an abortion storm in which a large percentage of cows abort.
There are many causes of abortion, both infectious and noninfectious, but one of the most common in cattle in North America is a microscopic parasite called Neospora caninum.
It was discovered by researchers in the late 1980s and was first described as a cause of abortion in cattle in Canada in 1994.
One particularly severe abortion storm was found in a northern Alberta herd in which 44 percent of the cows did not become pregnant or experienced fetal loss.
While this type of severe outbreak is not common, Neospora caninum is still considered one of the most common infectious causes of abortion in Canadian cattle.
The primary hosts are members of the canine family.
Dogs and coyotes can become infected and pass infectious cysts into the environment in their feces.
If a cow consumes this fecal matter while grazing or while eating contaminated feed, it can become infected with the parasite.
This can result in early embryonic death, abortion or a stillborn calf.
Cows that become infected carry the parasite for life. Although they do not pass the infection to other cows, they can pass it to their calves through the placenta. This dam-to-calf transmission can gradually increase the level of infection in the herd.
The cows that are carriers will always have a slightly increased chance of abortion in subsequent pregnancies, although many will conceive and have normal calves in the future.
A study funded by the Canadian Cattlemen’s Association in 2003 provided a snapshot of this disease in Canada.
Researchers sampled almost 5,000 cows from 179 herds across Canada. Although only 6.2 percent of cows tested positive for antibodies to the parasite, more than 40 percent of herds had two or more cows test positive.
The widespread level of infection in
cattle herds and the nature of its spread by dogs or coyotes make control of this parasite difficult. It is almost impossible to avoid having cattle come into contact with dog or coyote feces in western Canadian cow-calf herds, but dogs’ access to feed bunks and feed storage areas should be minimized as much as possible.
Producers can also lower the risk by ensuring that aborted or dead calves are not left out for coyotes or family dogs to consume.
Diagnosis involves sending aborted calves to a diagnostic laboratory. Blood samples from cows can help assess the level of infection in a herd.
There is no treatment for this parasite and control is obviously difficult.
Veterinarians can help diagnose an abortion problem in the herd and provide advice on developing a biosecurity program.
John Campbell is head of Large Animal Clinical Sciences at the University of Saskatchewan’s Western College of Veterinary Medicine.
