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  • Writer's pictureDonald Coover, DVM

Neospora: A Herd Health Problem You Should Avoid...

Updated: Feb 14, 2020

As a practicing veterinarian, I am often asked “What can I do to make my herd more profitable?” There can be, and are, a lot of different answers to that question but generally the answers are all geared toward more or more efficient production. That might mean fine tuning nutrition, better vaccination programs, better parasite control, better and more productive/efficient genetics, and so on, but all the answers depend on having live, healthy calves. There is a herd health problem that producers frequently ignore that is costly and common.

That problem is a parasite infection called Neospora Caninum. Cattle are one of the intermediate hosts of this parasite that causes mid to late term abortions in infected dams. According to the Veterinary Merck Manual, “Neospora Caninum is found worldwide, and is the most common cause of abortion in dairy and beef cattle in many parts of the USA.” If you live in the Midwest area of the US, like I do, you likely have cows and heifers infected with this organism, and it is costing you pregnancies and calves. The incidence we found in a fairly large study we did several years ago showed 8.9%of 5800 cows tested were infected. The cows sampled or tested were from Kansas, Nebraska, Missouri, Oklahoma and Arkansas. That works out to about 1 out of every 11 cows.

In order to deal with this parasite, you need to know something about it. While infected dams will abort much more frequently than non-infected animals, infected dams will frequently deliver live, apparently healthy, calves. Live calves born to infected dams are almost always infected with Neospora at birth, greater than 85% of the time. When these infected calves mature to cows, they are in turn also more at risk for abortion than non-infected females, making them less productive animals.

Infections that are passed from dam to offspring are called vertical transmissions. Animals that are not born infected (because their dams were not infected) can become infected with Neospora Caninum by eating silage, hay, or other feedstuffs contaminated with feces from dogs, foxes, or coyotes that are infected with the parasite. Canines are the definitive host of this parasite and, if they are infected, shed the organism in their feces. Intermediate hosts, like cattle, do not shed the organism in their feces, but do pass the organism in aborted fetuses and tissues. Canines that consume the aborted tissues will become infected, completing the life cycle.

Unfortunately, the only current method of controlling the abortion problem due to Neospora infections in cattle is to test for the carrier status in your cows and heifers, and then to select against the carriers. Parasiticides, or wormers, do not affect the parasite, and won’t guard against infections or the abortions the infections cause.

The test used to detect Neospora infection requires a blood or serum sample in a red top tube and costs a producer around $5 per animal tested. Here at SEK Genetics we test thousands of samples for Neospora infection every year, often after a producer realizes he has had pregnant cows show up open at calving time. Neospora is certainly not the only cause of pregnancy loss, but it is one of the more common causes. At a minimum, we strongly encourage producers to screen their replacement heifers and embryo transfer recips for infection status.

If you want to ask questions, get more information, ask about testing, or get supplies for testing animals, contact us at SEK Genetics, 1-800-443-6389, or 1-620-763-2211, or

By the way, if you have an animal (cow or heifer) that is infected but has genetics so valuable you can’t afford to cull her, you can harvest embryos from infected dams, transfer them to clean recips, and produce clean calves from infected donor dams. You should always test your recips if doing ET work, to guard against unnecessary pregnancy loss.

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