March 2005

Battling EPM: Choose Your Weapons

Immunostimulants may not be a good idea.

Is that injection really necessary?

It makes sense to state that a horse with a weakened immune system is more susceptible to infections. And usually this is true, but it’s not likely the case with EPM. Several studies with horses and mice show that a suppressed immune system—whether induced or due to an immune-system disease—may actually somehow protect the horse from EPM symptoms. In fact, stimulating the immune system the wrong way may make things worse.

In 2001, a study (Sanville et al) reported that horses stressed by transport prior to being fed the EPM organism developed more severe symptoms. This part of the report fit well with the idea that suppressed immune responses are involved…