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