Vet Talk: Neospora Infections

Vet Talk: Neospora Infections Do You Have Carrier Cows?

Dr. Donald P. Coover, DVM, SEK Genetics

What is Neosporosis?

Neosporosis is a fairly recently recognized coccidian parasite that is a major cause of abortion in cattle. First reported in New Mexico in a dairy herd in 1987, it is now considered a major problem and cause of abortions in dairy cattle, and can be just as big a problem in beef herds. One of the biggest problems with Neospora is that apparently healthy cows may have a chronic, lifelong infection, and this infection makes the cow several times more likely to abort a pregnancy. Just as important, cows that are infected will very likely pass the infection on to their calves, and the calves will be infected from birth.

While not all cows chronically infected with Neosporosis will abort, they are, according to research, at a 3 to 7 times greater risk of abortion than Neospora negative, non infected herdmates. Those Neospora positive cows that do not abort have a high probability (80 to 90%) of producing calves that are congenitally infected with Neospora.

It is a good idea to screen your cowherd for carrier animals, and to select against keeping Neospora positive animals. If you are involved in an ET operation, again, it is a good idea to screen your recips for Neospora infection. Remember, recips infected with Neospora will be more prone to late term abortions, and even if they do not abort, it is likely the ET calf born to them will be infected with Neospora at birth.

Why should I test my herd?

Recently, we helped a producer blood test one of his herds for pregnancy status in March. Most of the cows in this herd were 90 days or more into gestation when tested. The producer took the 121 pregnant cows in the group, and moved them to a different pasture for the summer. He noticed a few cows showing estrus, and decided in late June to see how many had lost their pregnancies. He again pulled blood samples for us on all 121 cows, and we again tested all the cows for pregnancy status.

Seven turned up open, a 6% pregnancy loss rate. After some discussion, and ruling out other likely causes of pregnancy loss, we tested the seven cows that lost the pregnancies for Neospora infection, and all 7 were seropositive, indicating they were all chronically infected. We tested the other 114 cows in that group for Neospora infection, and only 6 more were seropositive, for a total of 13 Neospora positive cows out of 121 (an 11% infection rate). Seven out of 13 Neospora positive cows aborted (or 54% of the Neospora positive cows) and none of the 108 Neospora negative cows aborted. It is very important to note we were not able to examine any aborted fetuses to determine the cause of abortion, however, we very strongly suspect Neosporosis.

After the above experience, we screened over 5000 blood samples submitted to our lab for Neospora infection. We found, to our surprise, that 8.9% of the blood samples indicated the source cow was infected with Neospora. A much smaller screening of sale barn cows indicated a much higher infection rate. We found a positive correlation between Neospora infected cows, and cows that tested open, especially if the pregnancy test was conducted late in the expected pregnancy.

The above example illustrates one of the very best reasons for closely monitoring the reproductive status of your cowherd. Pregnant cows should maintain their pregnancy status, and present you with an on time, live, normal calf. A “higher than normal” pregnancy loss indicates some problem, and you and your veterinarian should investigate. Common herd health problems are animals that are persistently infected with BVD virus, and cows that are chronically infected with Neospora. In both cases, the animals appear normal, and both will cause abortion losses year after year.

How do I test my herd?

There are many new and emerging technologies that help producers maintain more efficient and profitable cowherds. Blood pregnancy tests are easy to use, accurate, inexpensive and convenient, and show which cows are pregnant and productive, and which cows are not. Tests for disease conditions, like persistently infected BVD and Neospora, can help producers cull those animals that will cost them money before they do further damage to their bottom line. These tests are, like the blood pregnancy test, inexpensive and convenient. Work with your veterinarian to develop a plan to monitor your herd’s reproductive health, to anticipate, detect and solve problems, and to educate yourself about what is available.

I am Dr. Don Coover, a veterinarian with SEK Genetics. Besides offering semen, supplies, equipment and training to the AI industry, we operate a lab to test for pregnancy status using blood samples, detection of persistently infected BVD animals, chronically infected Neospora carriers, Johne’s affected animals, Bovine Leukosis infection, and so on. We also offer complete embryo transfer services, including embryo collection, transfer and sales. If you have questions about anything discussed above, contact us at 800-443-6389, or contact your veterinarian. There are good technologies available to help you avoid unnecessary losses, and they are increasingly available and affordable.

•   bioPRYN Blood Pregnancy Test: $2.60/ head

•   Neospora Test: $4.50/ head

•   PI-BVD Test: $3.50/head

•   Leukosis (BLV): $4.50/head

•   Johne’s Test: $6.50/ head 10 or more samples $4.50/head

Dr. Donald P Coover  •   SEK Genetics, Inc.  •   9525 70th Road  •   Galesburg, KS 66740

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