If you are lucky enough not to need your vet for an emergency this year, you should still see them at least once: for your horse’s annual vaccinations. Disease prevention is an essential part of proper horse management, but there is now a wide range of vaccines available and understanding which ones to have is essential and need not be seen as confusing.
Vaccines work by pretending to be specific viruses or bacteria and priming the immune systems of your horse against them. Subsequently, if those real pathogens infect your horse, they can fight them off before they are able to multiply and make the horse ill. Vaccines, typically, either contain killed or live agents of the disease that they protect against but most importantly, those vaccinal agents are no longer able to cause disease.
The first time that your horse encounters an attacking microorganism their immune system does not react very strongly. However, the immune system is able to ‘remember’ what individual pathogens look like. The next time the body meets that pathogen, the defence response is much stronger, killing them off quickly before they make the animal ill. The more times the body has met a specific pathogen, the greater the strength of the immune system against it. Think about how all humans get chicken pox the first time they encounter it but that one exposure is sufficient to result in immunity for the rest of their life.
Most vaccines require a primary course of two injections 6 weeks apart to initially stimulate the immune system. The horse’s ‘memory’ of the vaccine only lasts a certain time and different vaccines will require boosters at different times. For instance, herpes virus tends to require 6 monthly boosters while influenza requires a 6 month first booster following by annual vaccinations.