October 3, 2023

Understanding Equine Cushing's Disease: What Horse Owners Need to Know

Cushing's disease, also known as pituitary pars intermedia dysfunction (PPID), is a common endocrine disorder that affects horses, especially those aged 15 and older. This condition occurs when the pituitary gland, located at the base of the brain, becomes overactive and disrupts the horse's hormonal balance. This disorder leads to an overproduction of certain hormones, including adrenocorticotropic hormone (ACTH), which stimulates the adrenal glands to release excessive cortisol. Elevated cortisol levels can result in a range of health issues, including insulin resistance, laminitis, muscle loss, and a compromised immune system.

Spotting the Signs

Identifying Cushing's disease in horses can be challenging, as its symptoms can vary widely. Common signs to watch for include:

  • Abnormal Hair Growth: Horses with Cushing's disease often exhibit long, curly, and delayed shedding of their winter coat. This is the most common symptom.
  • Muscle Wasting: Progressive muscle atrophy, especially along the topline, can be observed.
  • Increased Thirst and Urination: Horses may drink and urinate excessively.
  • Laminitis: Hoof problems, lameness, and a propensity for laminitis can occur.
  • Potbelly Appearance: Some horses develop a noticeable potbelly due to muscle loss and abnormal fat distribution.
  • Excessive Sweating: Increased sweating, particularly in colder weather, may be observed.
  • Susceptibility to Infections: A compromised immune system can make horses more susceptible to infections and delayed wound healing.
  • Behavioral Changes: Alterations in behavior such as lethargy, aggression, or depression can occur.

Insulin Resistance Connection

Some PPID-afflicted horses may also become insulin resistant. This means their tissues don't respond well to insulin, leading to high blood insulin levels. Insulin resistance can cause muscle loss, fat accumulation, laminitis, and other problems.

Getting a Diagnosis: What You Need to Know

So, your horse might have Equine Cushing's Disease, also known as Pituitary Pars Intermedia Dysfunction (PPID). The best sign of PPID is that long, curly coat in older horses. For those with subtler symptoms, tests are available.

What's Happening Inside

In horses, the pituitary gland is in charge of making ACTH, a hormone that tells the adrenal gland to release cortisol. Now, in the fall, there's something called a "seasonal rise." It's a natural increase in ACTH production, and it's usually not a big deal for most horses. However, older horses or those in the early stages of PPID might struggle with it and get a painful hoof disease called laminitis during the fall.

Diagnosis Methods

To figure out if your horse has PPID, vets often check the ACTH levels. But here's the thing: they used to avoid doing this in the fall because of that seasonal rise we talked about. However, research has shown that horses with PPID have a more significant ACTH increase during the fall. So, testing in autumn is actually a smart move. They even have special guidelines for when to test during the fall. The Equine Endocrinology Group suggests checking between mid-July and mid-November.

Now, outside of fall, plain ACTH testing might miss early-stage PPID. In that case, your vet might use something called the TRH stimulation test in non-fall months (mid-November through mid-July). This test is like a dynamic diagnostic adventure. The vet takes a blood sample for ACTH, gives your horse synthetic TRH, and then checks ACTH levels again after 10 minutes. This helps spot PPID even when regular ACTH levels look normal.

Effective Treatments for Equine Cushing's Disease

While Cushing's disease is a chronic condition without a cure, several treatment options are available to manage its symptoms and improve the horse's quality of life:

  • Dietary Management: Feeding a low-starch, low-sugar diet can help control insulin levels and manage the condition's metabolic aspects.
  • Medications: Veterinary-prescribed medications, such as pergolide (Prascend), are often used to suppress excessive hormone production. Administering these medications as prescribed is crucial.
  • Regular Exercise: Maintaining an appropriate exercise regimen can help manage weight and improve overall health.
  • Supportive Care: includes regular deworming, dental work, and proper farrier care.
  • Hoof Care: Due to the increased risk of laminitis, diligent hoof care and management are essential.

Prascend Treatment and Rebates

Prescend is a widely used medication for managing Cushing's disease in horses. It contains pergolide mesylate, which helps regulate hormone production. As part of Cushing's awareness efforts, Boehringer Ingelheim, the manufacturer of Prascend,  offers rebates to horse owners. These rebates can help alleviate the financial burden of ongoing treatment.

Be sure to check out their rebate program.

In conclusion,

Cushing's disease is a manageable condition that requires diligent care and attention, especially during the fall season. By recognizing the symptoms, seeking proper veterinary care, and considering treatment options like Prascend, horse owners can help their equine companions enjoy a comfortable and fulfilling life despite this challenging condition.