Healthy Heifer: Think Safety When Vaccinating Pregnant Cows
10/06/2009 12:55PM
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Beef producers invest a lot of time, energy and resources to get cows pregnant. To protect that investment, an increasing number of producers are becoming more vigilant about maintaining effective vaccination programs that are safe for pregnant animals.
Preventing diseases that can have devastating effects on reproduction, such as infectious bovine rhinotracheitis (IBR), has proven to reduce reproductive failure and abortions.
For example, a study evaluating the ability of an inactivated bovine herpesvirus-1 vaccine to lower the risk of abortions caused by a virulent IBR challenge was recently published in the Journal of the American Veterinary Medical Association (JAVMA). IBR is a highly contagious infectious disease that can typically cause abortions at five to six months gestation.
The study involved a group of beef heifers that were either vaccinated according to label instructions with Vira Shield® 6 at prebreeding or remained as nonvaccinated, control animals. All heifers were challenged with virulent IBR virus at approximately six months of gestation.
Eighty-five percent of the vaccinated heifers were protected from abortion and all of their calves were found to be normal. Conversely, 100 percent of the nonvaccinated control heifers aborted—a testimony to the strength and severity of the virus challenge.
The objective of the study was to evaluate the efficacy of an adjuvanted, inactivated IBR vaccine administered prior to breeding. And the results show that the vaccine protected against IBR fetal infection eight months post-vaccination with efficacy similar to that of modified-live IBR vaccines.
Focus on Safety for Pregnant Cows
It’s important to keep in mind that IBR modified-live vaccines can be abortifacient agents—meaning they can actually cause abortions—when used off-label. This is why they typically carry specific label precautions with regard to use in pregnant cows and calves nursing pregnant cows.
In fact, in 2006 South Dakota State University reported an increase in the number of cases of IBR-caused abortions associated with improper use of modified-live IBR-BVD vaccines.1 Additional scientific evidence suggests that modified-live IBR vaccines should not be administered during estrus in seronegative, or unexposed females.2
Considering those safety limitations, one option for producers that reduces the risks that may be associated with modified-live IBR vaccines is to use a properly inactivated and adjuvanted vaccine.
“By using the Vira Shield 6 line of vaccines, producers can gain the advantages of vaccinating without the complicating restrictions that modified-live vaccines are required to carry,” says Doug Scholz, DVM, director of veterinary services, Novartis Animal Health. “Vira Shield 6 is demonstrated to provide enhanced IBR fetal protection without the safety risks that may be associated with modified-live IBR vaccines.”
1. Daly R. Timing of vaccinations in beef cattle herds. Paper presented at: Applied Reproductive Strategies in Beef Cattle, September 11 – 12, 2007; Billings, Montana.
2. Chiang B. et al. The effect of infectious bovine rhinotracheitis vaccine on reproductive
efficiency in cattle vaccinated during estrus. Theriogenology 1990;33:1113-1120.
Vira Shield is a registered trademark of Novartis AG.