Understanding your horse’s immune system

How does the immune system work?

The horse’s immune system is designed to fight off infection and sometimes threats from its own body such as autoimmune diseases and cancers. There are three broad components to the immune system:

Physical barriers such as the skin.The innate immune system, which non-specifically guards against threats when they first enter the body.The acquired immune response, which takes longer to activate but responds very effectively to specific diseases.

The role of antibodies

One of the ways in which the acquired immune system works is to create and maintain enough antibodies (a type of protein) in the blood that can identify and neutralise foreign objects within the body such as bacteria and viruses. Another important role is ‘cell-mediated immunity’, which involves the production of white blood cells that specifically fight infections without the production of antibodies. All these components work together to provide protection for your horse.

What can compromise the immune system?

The immune system can be compromised by many things such as the amount and type of pathogen (bug) it has to fight off as well as the horse’s natural ability to fight disease. Youngsters, older horses and those that have other disease challenges, for example Cushing’s, will often have compromised immunity.

What do vaccinations do?

Prevention is key to the control of equine disease. The intention is to reduce the level of challenge whilst maximising the horse’s immunity and vaccination is one of the most important ways to help achieve this. Vaccinations have two main functions, depending on the type of disease. The first is to provide protective immunity against diseases such as tetanus. The second is to reduce the spread of contagious diseases such as equine influenza.

How do vaccines work?

Simplistically a vaccine imitates a specific disease in order to stimulate the acquired immune response more quickly and with greater magnitude than in an unvaccinated horse. The immune system then communicates with the other body systems to regulate and destroy this foreign material or ‘pathogen’. Vaccination helps to provide protective immunity, priming the animal’s own immune system to allow it to remember specific diseases. This enables it to mount an improved immune response more quickly and with a greater magnitude when challenged in the future.

To work successfully an effective vaccine must be used and the horse must have a healthy immune system, both at time of vaccination and at time of challenge. However, because each horse is an individual, some may respond differently to others to exactly the same vaccination protocol.