3. I NTERNAL PARASITES

Deworming is vital because certain parasites can overwhelm a young horse’s still-developing immune system.

of a good thing is not a good thing. I always prefer babies to be on the slim side rather than obese. It’s better for their joints and their whole body and longevity. You don’t want them starving, but I like to see them athletic rather than fat or growing too fast,” she says.

Lack of exercise can also lead to DOD. “It’s amazing how many people make the mistake of putting the baby in a stall so he will be protected or to get him ready for halter classes at a show,” says Connally. “Too much pampering and protection will result in a horse that won’t hold up as an athlete.” That said, too much forced exercise can also be detrimental. Turnout in an active herd will encourage most young horses to move enough to keep their joints healthy without damaging them.

However a youngster is managed, be on the lookout for DOD as he grows. “By the time a horse is a yearling or 2 years old, trying to correct these with management is nearly impossible,” says Connally. “By then we’ve lost a lot of our opportunity to affect the growth plates; they are already closed or closing.”

Connally adds, however, that treatment is still possible: “If you x-ray those joints you can see the lesions and figure it out and get some treatment. In many instances it will be surgical treatment, although people have done some other things like shock wave therapy, which might help.”

Because the immune system is still maturing during the first years of life, young horses are particularly susceptible to certain internal parasites, such as ascarids . The solution, of course, is deworming. However, unlike older horses, who do best with targeted deworming primarily based on fecal egg counts, young horses---particularly foals and weanlings---benefit from deworming based on a schedule devised to protect them from the most common threats: ascarids and small strongyles, which can be acquired through a dam’s milk.

By the time a youngster is a year old, he may have developed sufficient immunity to be dewormed based on fecal egg counts like mature horses, but your veterinarian will determine the best approach. Immunity will continue to build until the horse is around 5 years old, so his treatment plan may be continually adjusted until then.

Keep in mind

Turnout in an active herd will encourage most young horses to move enough to keep their joints healthy without damaging them.