Equine Internal Parasites Effective control programs for equine internal parasites.
All horses have internal parasites.
Fifty percent of the deaths in horses may be related to internal parasites. Internal parasites have adapted themselves to the internal environment of their host animal and have become host-specific. Horse parasites can only exist in horses and cattle parasites only in cattle. This can be a factor in developing parasite control programs. Strongyles can be seen in horses of all ages, except in very young foals.