Horse Illustrated Magazine

Q: My senior horse has Cushing’s disease. Can you recommend some optimal diet plans?

A: It is not uncommon for an older horse to develop pituitary pars intermedia dysfunction or PPID, most often referred to as Cushing’s disease. Aside from their tendency to sport a long and shaggy hair coat

that sheds unevenly, horses with this malfunction of the pituitary gland often display muscle wasting along their toplines and hindquarters, yet they may have a potbelly appearance.

The goal in feeding a horse with Cushing’s,  is to limit the intake of nonstructural carbohydrates (NSC) feeds, such as the sugars and starches found in grains. In many cases, feeds that are labeled as “senior” feeds are also high in NSC content and should be avoided when feeding a horse with Cushing’s disease.

The objective is to feed a diet that has less than 10 to 20 percent of total digestible energy (the combination of sugars and starch, or NSCs). High-fiber components, such as these found in hay, hay cubes, pasture, and beet pulp, should constitute the main portion of a senior horse’s diet. Most horses will eat between 1½ to 2 percent of their body weight per day in forage. (For example, a 1000-pound horse should be fed 15 to 20 pounds of hay per day.)  It is important to recognize that some hays may contain high levels of NSC, depending on the species of grass and when and how it was harvested. Older horses often have dentition problems, too, so provide good quality hay and feed that is easy to chew.

In general, you’ll want to avoid all grain and/or feed with molasses, this includes eliminating treats, horse cookies and candies since they are high in sugars.

If more calories are needed to maintain body condition, then in addition to feeding good quality forage, substitute high-fat supplements (oil and/or stabilized rice bran) for grain.

A Cushing’s horse also benefits from the effects of medication like pergolide, which can reduce the clinical signs and secondary effects of the pituitary malfunction. This medication facilitates the horse’s best use of a Cushing’s “diet.”

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