This article discusses some diseases that could be a problem if abortions or repeat breeding are occurring in a herd.
The following article discusses some diseases that could be a problem if abortions or repeat breeding are occurring in a herd. They are important to keep under control, as reproductive disease outbreaks can be a significant economic loss. For most of these diseases, vaccination is a valuable tool in prevention. If vaccines are used, be sure to administer them properly, according to directions and to give required boosters. Otherwise, maximum immunity and protection will not be achieved.
BVD (Bovine Virus Diarrhea)
A viral disease that can cause abortion, death, pneumonia, diarrhea, fever, lameness and susceptibility to other diseases
Cows become persistently infected in utero, during the first 120 days of gestation. Because infected animals are not always easily detected, these are the animals in a herd that will spread the disease. Infected animals shed the virus in the manure and in bodily secretions. The only way to know for certain which animals are infected is with a blood test. Once thought impossible to eradicate, BVD has been certified as eliminated in at least two herds in the U.S., as well as many herds in other countries.
Prevention measures: Test all animals entering the herd for BVD. It is a relatively inexpensive test. In addition, it is good practice to isolate new animals, ideally for 30 days. If possible, buy replacements from herds that are known to be BVD-free. Consider buying open cows, to minimize the chance of getting a BVD infected calf. Keep the existing herd properly vaccinated and avoid manure contamination of feed and water. Ensure adequate colostrum intake in calves and provide and stress-free environment and proper levels of nutrients that boost the immune system such as Vitamin E, selenium, copper and zinc.
IBR (Infectious Bovine Rhinotracheitis)
A viral disease causing embryonic death and abortion, usually after the 4th month of pregnancy. Often, an exposed animal shows no signs of the disease. It is not until the virus becomes activated by stress that problems can occur. At that point, the infected animal can shed the disease and cause an outbreak in a herd
Prevention measures: Vaccination is the most effective method of prevention for this disease. There are many vaccine options available. The modified live vaccination (MLV) can provide lifetime protection. MLV should be administered after 6 months of age and should not be used in pregnant cattle at all. There are nasal spray and killed vaccines that can be used in pregnant cattle. These types of vaccines should be performed annually to provide maximum protection.
A protozoal infection of the coccidian Neospora caninum, that causes early abortions. This parasite is carried by dogs and possibly coyotes and is shed in their feces. Ingestion of contaminated feed, water or dirt is the route of infection. Infected animals can be identified by blood tests.
Prevention measures: Restricting dogs on the farm is the most important method of prevention. If you can't (or don't want) to keep dogs completely off the farm, at least keep them from areas where they will be in contact with feed or water sources. A new vaccine is available and may be worth considering if neospora or coyotes are a big problem in your area. Cows that test positive for Neospora will have calves that test positive as well. This, in addition to the fact that positive cows have been found to have decreased milk production, may make culling of Neospora-positive cows a decision to consider.
A very contagious disease mainly caused by two serovars, L. pomona and L. Hardjo. This disease can also be transmitted to humans. In cattle, leptospirosis (or lepto) causes late term abortions; other clinical signs can include fever, anemia and reddish urine. Animals that have been exposed and survive become persistently infected and can shed for years. The leptospires infect the kidneys and are shed in the urine. Lepto is also very hardy and can survive in standing water for up to 10 days.
Prevention measures: Blood tests can be used to identify infected animals, although the tests can be inconclusive. Culling of any cows that test positive is a good idea, especially as their calves can be born carrying the disease. Vaccination is probably the most reliable method of prevention. Improved vaccines are being developed that can help control this disease.
Vibriosis or vibrio is a bacterial disease that infects bulls. Cows become infected during breeding, either through live cover or artificial insemination. There are often no clinical signs of the disease in cattle. Vibrio causes early term abortions and embryonic death and may only be indicated by a high percentage of repeat breedings. Campylobacter is also a very common cause of bacterial diarrhea in humans.
Prevention measures: Prevention of this disease lies in making sure that all bulls used on the farm are not infected with Vibrio. There is a diagnostic culture that can determine the presence of the disease, although repeated cultures are often needed. Practice proper, hygienic AI technique. Vaccination can also be used and should be performed prior to breeding on an annual basis.