Why is my horse not shedding its winter coat? Understanding PPID in horses

As the seasons change, so do horses’ coats to help them stay warm in winter and cool in summer. But occasionally, horses can be late to shed their thick winter coats. 

While this isn’t always a problem, it can be a symptom of pituitary pars intermedia dysfunction (PPID), also known as equine Cushing’s disease.

Drs. Yatta Boakari and Sophia Marchio — veterinarians and equine health researchers at the Texas A&M College of Veterinary Medicine and Biomedical Sciences — explain the signs and causes of PPID.

PPID And Hormone Regulation

PPID is a disorder related to abnormal growths in the pituitary gland, a region of the brain that plays a big role in regulating the body’s hormones.

“The tumors cause an overproduction of certain hormones, leading to a variety of symptoms that can be different for each patient,” Boakari said. “The main issue that affects a horse’s quality of life isn’t the hormone dysregulation itself, but the many things it can lead to.”

One of the most iconic symptoms is an abnormally long coat that a horse doesn’t shed once winter is over, though not all horses with PPID get this particular symptom.

“It’s very important not to rule out PPID just because a patient doesn’t have the long coat that we associate with the disease,” Marchio said. “They can have many other symptoms, many of which are far more dangerous to the patient’s health and well-being.”

Other symptoms of PPID can include:

• Muscle loss
• Laminitis (inflammation of the hoof)
• Insulin resistance
• Chronic skin infections
• Reproductive abnormalities
• Weakened immune system

“We don’t yet know why horses with PPID develop different symptoms,” Boakari said. “That’s why it’s so important to consider a patient’s entire health history when making a diagnosis.”

Most horses that develop PPID are at least 15 years old, but not all are.

“PPID is more common with older horses, but, again, it should not be ruled out just because a horse is young or middle-aged,” Boakari said. 

When To Seek Out A Veterinarian

If your horse is experiencing any of the possible symptoms of PPID, it’s a good idea to contact your local veterinarian for advice.

“Patients with PPID have the best outcomes when they receive an early diagnosis,” Marchio said. “This way, your veterinarian can work with you to help manage the disease and maintain a good quality of life for your horse.”

Even if the symptom doesn’t turn out to be caused by PPID, it’s still important to get advice from an expert.

“Many of the symptoms associated with PPID are problematic on their own, especially laminitis, which can cause chronic lameness,” Boakari said. “All of the symptoms should be taken seriously.”

By Texas A&M University College of Veterinary Medicine and Biomedical Sciences

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