Dealing with respiratory diseases

Gary Sliworsky
Ag. Rep.

The viral respiratory diseases of cattle are BVD (Bovine Viral Diarrhea), IBR (Infectious Bovine Rhinotracheitis), PI3 (Parainfluenza Type 3) and BRSV (Bovine Respiratory Syncyntial Virus). These viruses cause problems not only as respiratory disease in stockers and feeders, but some of them also can cause abortion and other problems in infected cow herds. In some areas, herds are in close proximity which makes it difficult to isolate cattle enough to prevent transmission of these disease
Therefore, immunization becomes the method of choice for protecting herds. Today there are at least 150 products available for use in cattle that offer protection against these viral diseases. Some use killed viruses, some use modified live viruses (MLV), and some use a combination.
Killed vaccines cannot multiply in the animal, so they cannot cause disease or abortion. The immunity they produce is not as strong or as long lasting as that produced in response to MLV vaccines. Killed vaccines usually require a booster to achieve adequate immunity, and they will require annual vaccinations to maintain immunity over the lifetime of the animals. Killed vaccines usually utilize an additive that increases the immunity by increasing inflammation at the injection site. This leads to increased stress and hypersensitivity reactions.
MLV vaccines produce much stronger and longer lasting protection. Because they don’t depend on additive, they are less stressful. They require much less, if any, revaccinating throughout the life of the animal. On the down side however, is the fact that because they are live viruses which have been changed (modified) to reduce their disease causing ability, they may produce disease in some individuals.
They can cause abortions if they are given to pregnant females or calves nursing non-vaccinated cows.
It is usually not a problem to use MLV vaccines on calves nursing cows that have received MLV in the past. A good program is to use a MLV vaccine on replacement heifers at weaning and again at 12 months of age to achieve a long term protection, and to eliminate potential problems when vaccinating their nursing calves. This is less expensive than boosting every year with killed vaccines.
A word of caution: give the MLV vaccine at least 30 days prior to the beginning of the breeding season to prevent interference with ovulation.

Dates to Remember
·Sept. 29 – Regional Marketing Workshop, 9:00 am – 12:00 pm, La Place Rendez-vous
·Oct. 7 – Calf Sale, Stratton Sales Yard