Dr. Caity Cosentino
Properly administered vaccinations can prevent diseases in your horse that are detrimental to their health and even sometimes deadly. Vaccines are designed to reduce the risk for infection by working with the body’s own natural immune system. When your horse is exposed to a harmful virus or bacteria, the invading organism attacks the horse’s cells and multiplies. This is what causes infection and the signs off illness that you see. Horses have similar types of blood cells to humans. They have red blood cells which are responsible for carrying oxygen around the
body and to organs and white blood cells which main duties include fighting infection. There are multiple types of white blood cells in the body, but there are 3 main types that are responsible for the horse’s immune defense:
Macrophages, which ingest the invading germs as well as dead and dying cells and leave behind parts of the cells, antigens. B-Lymphocytes, which will respond to the antigens left behind, releasing antibodies that will attack the invading germs and T-Lymphocytes, which attack and destroy the cells in the body that have been invaded by the bacteria or virus.
After the horse has been infected, the body produces memory T-cells that will recognize the germ in the future and allow the body to respond quicker if the horse becomes infected again. The B-cells will also be ready to produce antibodies for that specific antigen. This way, the horse’s immune system may be able to fight the invader before any signs of illness are seen. Vaccines are designed to imitate a specific type of infection that will trigger the body’s immune response without causing the actual disease. The goal is to produce memory cells and antibodies that will respond to and fight the invading infectious agent. This process will take several days or weeks to be completed, leaving a window where the horse is still vulnerable to infection.
Vaccines that are commercially available are regulated by the federal government. They have rigid safety standards and standards for stability and efficacy. When handled properly, there are few reasons for failure. Lack of adherence to the directions on the label can cause a lack of vaccine efficacy as well as an increased risk of local vaccine reactions. Because the vaccines are designed to stimulate the immune system, there is always a slight risk for a reaction, even with a properly administered vaccine. Reactions are usually mild and include transient low-grade fever or swelling at the injection site.
There are several factors that can cause a horse to have a decreased ability to respond to the vaccine. Malnutrition and parasitism, high-stress levels, geriatric horses, and those with Cushing’s disease may not get the full benefit of the vaccines given. Even if this is the case, vaccines will often lessen the severity of the disease and the length of the illness if it is contracted. It is important to have a whole health plan with your veterinarian so that your horse can be provided with the best protection possible.
Vaccine companies will often stand behind their products and guarantee both effectiveness and safety if the product was purchased and given by a licensed veterinarian. Often the companies will reimburse medical expenses related to vaccine failure, or severe vaccine reaction, as long as the vaccine in question was administered by a veterinarian. Vaccines purchased and given by owners and other individuals do not carry the same protection as the proper handling of the product cannot be guaranteed. For this reason alone, it is a good idea to have your veterinarian administer all required and recommended vaccines. Different vaccines also have different protocols, some require boosters, some are required annually or more frequently, and foals are contending with left over maternal antibodies, so have a completely different protocol to adult horses being vaccinated.
Vaccines should be tailored specifically to each individual horse’s needs. Geographic location and exposure risks are all taken into account by your veterinarian when developing a vaccine protocol for your horse. This helps to ensure that your horse is protected as much as possible, without be over-vaccinated with things he or she may not need. Vaccination is an integral part to any good preventative health care plan, and it’s safest and most effective when done with your