Horse owners know that they should vaccinate their horses on a regular basis, but understanding vaccine mechanisms and why they work may not always be clear. Vaccines are carefully developed and tested to ensure their efficacy and safety. The best resource for understanding different types of vaccines is your veterinarian.
All vaccines are created to help prevent disease and contain antigens, which are derived from the disease organism. A few examples of antigens are viruses and bacteria. When administered to horses, the specific vaccine helps stimulate an immune response against that particular disease.
Vaccines may also contain an ingredient called an adjuvant, which is simply a substance that aids the antigen in stimulating an immune response. Adjuvants enhance the antigen presentation to the immune system and act as an additional foreign substance to help trigger a strong immune response.
So why do we need adjuvants if vaccine antigens already stimulate the horse’s immune system? Often, the antigens contained in vaccines are inactivated (killed) organisms. The organism is inactivated prior to being placed in the vaccine in order to prevent causing disease. Because inactivated infectious agents are not able to reproduce themselves as a regular organism would, the immune response they generate may not be strong enough to help fend off infection when the horse is exposed to the disease agent.
In the case of WEST NILE INNOVATOR® from Pfizer Animal Health, the vaccine contains the MetaStim® adjuvant system in addition to inactivated West Nile virus. The MetaStim adjuvant is formulated into tiny droplets, which contain antigens both on the outside and the inside of the droplet. When injected as part of the vaccine, the antigens dispersed in the adjuvant help stimulate the horse’s immune system to develop antibodies against West Nile virus that aid in the prevention of the disease. This is called a humoral immune response.
All horse owners want the best protection for their American Quarter Horses. Work with your veterinarian to determine the most effective protocol for your horses, based on each horse’s activities and risk of exposure to other horses. With a sound vaccination schedule, you can help keep your horses healthy for a successful summer season.
Photo: Regular vaccinations are vital to keeping your horses healthy. Journal photo.