Vaccines stimulate the immune system of the animal to produce antibodies.  Antibodies (or immunoglobulins) are proteins created by cells in the blood or in various lymphoid tissues that can be found in the intestine or upper respiratory tract. These specific proteins help to destroy various infectious organisms that can cause disease. Cattle also produce antibodies when they are naturally exposed to infectious organisms.

Vaccines are certainly a primary component of our modern herd health programs, but it is important to remember that they rarely provide absolute protection and other management components such as biosecurity, nutrition and environmental management also play important roles in protecting the herd from infectious diseases.

When cattle are exposed to infectious pathogens, the immune system is stimulated to respond to these infections. It takes time for this complex machinery to respond to a pathogen when it is initially exposed to the antigen (either through vaccination or natural infection). As a result, antibodies aren’t created in time to prevent disease from occurring on initial exposure. However, the immune system is able to “learn” and develop a specific response to a pathogen (a disease-causing agent) such as a particular bacteria or virus or parasite. This is important because when an animal is exposed to the disease for a second time, the immune system has memory cells that are programmed to respond to antigens they have previously encountered. Continue reading →