Many factors play a role in an animal's immune response to disease challenges
Protecting cattle from disease is the foundation of building a healthy herd. Vaccines, along with good nutrition, play a role in helping animals develop immunity against key reproductive and respiratory diseases.
It is important to begin with immunology basics. "Vaccination does not equal immunization," says Mark van der List, Professional Services Veterinarian with Boehringer Ingelheim Vetmedica, Inc. "When we talk about immunization, we actually mean protection from the invasion of a foreign protein into the body. Vaccination is simply the process of giving a vaccine. Vaccination can lead to immunization, but not if vaccines are improperly handled or administered."
When a foreign protein (antigen) enters a cow, systems that can identify self versus non-self are activated, explains Dr. van der List. Once the antigen is identified as non-self, the cow's immune system will set off a cascade of events and develop either a cell-mediated immunity or a humoral immunity, or a combination of both, to rid the antigen from the body. The immune system will also develop memory cells, which will enable the body to react much more rapidly the next time the same foreign antigen is encountered. Immunization is the development of these memory cells so that the body can rapidly deal with disease.
"When developing vaccines, we modify the organisms that we want protection against so that the animal doesn't have to suffer the full-blown disease to develop immunity," says Dr. van der List. "While one method is to expose the animal to others with the disease, there are huge risks involved with this. With a vaccine, we can take away a lot of that risk and still get the protection we desire."
Vaccinating when an animal is stressed can lead to problems, says Dr. van der List. To develop a good immune response, the animal needs to be healthy and stress-free. Stress releases cortisol, which interferes with immunity. This can lessen the animal's response to vaccination, as well as predispose the animal to disease. Producers should plan to administer vaccine ahead of an anticipated disease challenge, which is often associated with a stressful event. With a modified-live virus vaccine development of immunity can be rapid, however it is still advisable to have two to three weeks between administration and requirement of immunity, says Dr. van der List.
For heifers that have never been vaccinated before, a four-week period is especially recommended prior to breeding. He adds that with a killed vaccine, a booster will often need to be administered about three weeks after the first vaccination, so producers should plan for this extra time lag. Producers can provide the best opportunity for a complete immune response by conferring with their veterinarian to develop a protocol that uses the appropriate vaccines for the disease risks on the operation.
Dr. van der List also reminds producers to use vaccines according to label direction for greatest efficacy. Calves, heifers and cows undergo very different challenges. The biggest challenges herds face includes birth, weaning and calving, says Dr. van der List. The frequent mixing and transporting that today's herds face can also create a stressful environment for cows. He recommends that producers discuss potentially stressful situations with their herd veterinarian and herd management team and plan accordingly.
Dr. van der List says that vaccines are the least expensive and most effective form of animal health intervention producers can perform. He encourages producers to talk to their herd veterinarian about establishing good vaccine programs, because at the end of the day, vaccines could protect the whole herd from some pretty devastating diseases. For more information on the complete line of cattle reproductive and respiratory vaccines, please visit: www.bi-vetmedica.com/cattle.
Boehringer Ingelheim Vetmedica, Inc. (St. Joseph, MO) is a subsidiary of Boehringer Ingelheim Corporation, based in Ridgefield, CT, and a member of the Boehringer Ingelheim group of companies.