Cushing’s Disease


Horse feedQ: I have a 17-year-old Mustang that came back high on the ACTH test for Cushing’s disease. She started Pergolide 5 days ago. I have her on grass hay. My question is about treats and supplements. Most pellets have alfalfa in them. What is safe to feed my horse?

A: Equine Cushing’s Disease, or pars intermedia dysfunction (PID), is a resultant condition from benign tumor growth in the pituitary gland. Seen mostly in older horses, this clinical syndrome manifests itself in the forms of hirsutism (excessive hair growth and inability to shed a winter coat) and laminitis, as the pituitary tumor secretes excess hormones that cause the adrenal glands to produce large quantities of cortisol, a steroid. Steroids do many things in the body but in excess, can cause havoc with everything from immune function to carbohydrate metabolism and insulin resistance. For this reason, Cushing’s horses are prone to laminitis, thus the need for dietary restriction of carbohydrates and sugars. Pergolide is a drug commonly used to help control Cushing’s disease. Acting on dopamine receptors in the brain, pergolide helps regulate the excess secretion of hormones and peptides from the pituitary gland that cause clinical signs of this disease.

Grass hay is the ideal forage for a Cushing’s horse, since it is low in soluble carbohydrates and sugars. Lush pasture access should be limited in these horses. In terms of complete feeds, there are a few brands that have emerged recently on the market specifically for horses with Cushing’s disease and its sister disease: equine metabolic syndrome – an umbrella term for horses that are overweight, insulin resistant, and hyperglycemic. These feeds are low in starches and sugars and high in fermentable fibers. All the major horse feed companies seem to have their own formulas now, including Purina Mills, Triple Crown Feeds, and Blue Seal. Molasses-free beet pulp is also ideal – having a low glycemic index and high in fiber, beet pulp can help bulk up a horse’s feed.

In terms of treats for a Cushinoid horse, your options are limited. Most commercial horse treats contain high sugar content because, after all, they are a treat. Even “natural” choices for treats such as carrots and apples shouldn’t be given to Cushinoid horses. Instead, try celery. If your horse sticks his nose up at this healthy suggestion, sugar-free candies such as what you would find in the diabetic aisle of your grocery store can also be given. Sugar-substitutes such as Nutrasweet and Splenda will not harm your horse in small quantities. Another suggestion is to try the lowest calorie treat of all: an extra scratch on the ear speaks as a reward as well!

— Anna O’Brien, DVM

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  1. A 30 yr old horse at our barn has Cushings, but he has lost so much weight due to losing nearly all his teeth. He is literally skin & bones & we are doing everything we can to keep the weight on him. He is being fed soaked alfalfa cubes because he cannot eat hay & two 10 lb feedings of soaked grain not to mention as much grass as he can eat. Its been a struggle to keep the weight on him and keep him healthy. He’s also on pergolide but don’t know if it really is helping him. He does appear to be happy and loves to be petted and brushed.

  2. Thank you for this article. I think we all need to be as informed as possible about these illnesses so that we can better care for our buddies!

  3. My instructor’s horse has Cushing’s and laminitis. He has been off for 7 months and is now back to doing lessons and barrel racing. He eats bermuda and rice bran pellets and is on pergolide and is in great condition. Oh, and did I mention, he’s 25?

  4. This is basically the diet I feed my horse. I think it’s good for a maintenance diet even for healthy horses which mine is.

  5. My horse has cushings and I need to know a good riding routine for him. Right now I do this walk, trot, controlled trot, canter, and then usually go on trail. Is there anything that I can do for him that will put him at a lower risk or getting injured or even worse. With him arthritis, cushings, and having him being a fragile 24 years old please help me and give me hints. Email me at

  6. As far as treats go, BEET-E-BITES are designed with these horses in mind! They are a delicious treat in 4 flavors, and tested to be under 10% NSC!
    Great article, but remember, all grass hays need to be tested as they can be as high as 30% starch/sugar!

  7. I thank Horse channel for the great info of cushings disease. My horse has all the signs of cushings. My horse has laminites but he is all most 100% sound and I thank the LORD for that. I have been asking God to take care of him and He has been doing that !!!

  8. My 29 year old Salsa has just been diagnosed with early cushings we live in Spain, grass hay is like gold dust in southern spain , they are both on Bio not sure what that is in English, its a substitute for hay as that is difficult to get consistantly. She was on alfalfa pellets, a small amount of a horse mix, and molly chop. She has glucosamine for her joints they are fine but at her age I thought it a good idea as my joints ache and it helps me. We had her on red cell but as we dont ride that much for both our sakes, particularly in summer, she has not been on it for a while. Her only symptom is the shaggy coat that lasts most of the summer. She is 15.2 I have got vits C and E for her, but do not seem to be able to get the perogolide here. My vet is away till oct so am at a loss what to do. I am slowly changing the alfalfa for sugar beet and have reduced her carrot and apple intake by half then will reduce it again next week as she does not react well to sudden dietary changes. Any suggestions horse vets are at a premium over here. Thankyou Sheila


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