Five Tips About Caring for a Horse With PPID (Cushing’s Disease)

If you own a horse for a long enough time, the odds are good that as the horse ages, he or she could be affected by Pituitary Pars Intermedia Dysfunction (PPID), better known as Cushing’s disease. This age-related endocrine disorder, which is often seen in equines older than 15 but has been diagnosed in horses as young as seven, has no cure. If left undiagnosed, it could lead to severe secondary conditions that could negatively affect your horse’s quality of life.

Quarter Horse News spoke with Dr. Jen Voellinger of Precision Equine in Springtown, Texas, to get the lowdown on what a Cushing’s disease diagnosis means for your horse.

The Pituitary Gland Is the Culprit Older horses can benefit from regular veterinary visits. * Photo from Pexels

PPID is caused when a horse develops benign tumors in a section of the pituitary gland called the pars intermedia. These tumors cause an overproduction of hormones, affecting the horse’s metabolic functions, blood pressure and electrolyte balance. This can lead to secondary complications such as heat intolerance, muscle wasting, weight loss, a suppressed immune system, chronic skin infections and general ill thrift.

PPID is not preventable; there is no supplement or medication you can give to ensure your horse doesn’t develop it at some point in their life. The only known significant risk factor at this time is age, meaning any equine older than 15 has a chance of developing the disease. Therefore, as your horse ages, it’s important to schedule regular check-ups with your veterinarian, who can keep an eye out for early signs.

“I am always evaluating older horses for clinical signs of PPID,” Voellinger said. “Early detection and treatment are important to decrease the negative consequences of the disease, like infections and laminitis. This would increase the quality and length of the horse’s life.”

Common Symptoms Aren’t Always Seen

The most infamous symptom of Cushing’s is a long, curly coat that doesn’t shed out well after winter. Many horses have to be body clipped as temperatures warm up due to delayed shedding. You can also watch for muscle loss, especially over the topline, increased thirst, excessive urination and decreased energy.

“Other less common signs could include abnormal sweating from heat intolerance, exercise intolerance, a rounded abdomen, chronic skin infections and a thick, cresty neck,” Voellinger said. “These can lead to complications like higher parasite burdens, recurrent infections, laminitis, foot abscesses and slow wound healing.”

Laminitis, which presents as foot pain, is the most devastating complication of PPID. In a laminitic horse, the tissues anchoring the hoof wall to the underlying bone are weakened, causing the bone to rotate inside the hoof capsule. This causes severe, chronic lameness that some horses may never recover from.

Screening Tests Are Necessary for Diagnosis

If your veterinarian suspects PPID based on your horse’s clinical signs, he or she will do some diagnostic testing. This will measure baseline adrenocorticotropic hormone (ACTH) levels, which are usually elevated in advanced Cushing’s horses. Horses in the early stages of PPID may not show increased levels yet, in which case your veterinarian may decide to begin treatment anyway or order further testing like the thyrotropin releasing hormone (TRH) stimulation test.

Proper treatment of PPID can prolong a horse’s life. * Photo by Helena Lopes via Pexels

Since PPID can coexist with Equine Metabolic Syndrome (EMS), it is important to also test for insulin dysregulation, Voellinger noted. EMS horses produce higher than normal levels of insulin when they eat certain carbohydrates and are slow to return to baseline levels. They, like Cushing’s horses, may present with a cresty neck and are also predisposed to developing laminitis. Unlike Cushing’s horses, most EMS horses are overweight, but thinner horses might still suffer from insulin dysregulation.

Prognosis Is Reliant Upon Early Detection

Just like there is no prevention for PPID, there is also no cure. However, PPID that is caught and treated early can have a good prognosis, depending on how easily it is controlled with treatment.

“PPID is treated with Prascend, which is the only medication licensed for the treatment of PPID,” Voellinger said. “Horses that do not respond to high doses of Prascend may also require cyproheptadine, or Periactin. Routine veterinary care, including dental examinations, vaccinations, deworming and bloodwork; an appropriate diet and exercise program; and routine farrier work are all key to a better outlook for Cushing’s horses.”

Your horse may require a reevaluation of its diet, especially if he or she also has EMS. Since many horses with PPID struggle to maintain weight, a change of feed, such as switching to a complete senior feed, may be necessary, particularly if your horse can no longer chew hay. Horses that are obese may benefit from weight loss, which can improve their metabolic state.

Careful Treatment Can Prolong Riding Years

When performance horses are managed well and taken care of over the course of their lives, it’s common to see them competing well into their late teens and twenties. While Cushing’s can complicate things, it doesn’t have to mean the end of your horse’s riding years.

A PPID diagnosis may require a change in the way you work your horse, though, especially if it is struggling with temperature and exercise intolerance. You will also likely need to repeat ACTH testing to verify the medication is regulating the disease. Any changes in your horse’s weight, hair coat, muscling or soundness should be communicated to your veterinarian immediately.

“Care should be taken to properly manage and treat the horse, which could include modification of the horse’s exercise routine or athletic demands,” Voellinger said. “That protocol should be tailored to each horse and should have veterinary oversight.”