EQUINE CUSHING DISEASE

Is your horse or pony not shedding its long winter coat properly, or has recurring bouts of lameness for no apparent reason? Perhaps you’ve noticed s/he is drinking a lot of water, and urinating more. If so, they may have developed Equine Cushings disease. Whilst this disease is usually associated with older equines, it can actually develop at any age. Likewise, although it tends to be more common in ponies, equines of all sizes are not immune.

Cushings disease, or PPID (Pars Pituitary Intermedia Dysfunction) is brought on by a benign tumor or growth (a pituitary adenoma) in the middle part of the pituitary gland. As part of the endocrine system, the pituitary produces hormones that regulate a number of other organs. When it malfunctions, this then affects the functioning of those organs, resulting in diseases like Cushings.

SYMPTOMS OF EQUINE CUSHINGS

Cushings symptoms vary between individuals. Some are textbook cases whilst others require testing to confirm the disease. However, if you’ve ever seen a horse or pony with Cushings, it probably did have a long wavy coat. This is a very common symptom of the disease, and usually one of the first things owners notice, along with the abnormal coat shedding.

Another common symptom is those unexplained bouts of lameness. Unfortunately, the Cushings is usually quite advanced by the time these symptoms become noticeable.

Other Equine Cushings symptoms include:

Increased drinking – this is common with Cushings in other species as well
More frequent urination
Increased appetite
Pot belly
Lethargy
Muscle atrophy
Increased vulnerability to parasitic worms, notably tape worms
Impaired immune system function which often presents as persistent respiratory and skin infections
Abnormal fat deposits above the eyes and across the tail head

DIAGNOSING EQUINE CUSHINGS DISEASE

Often just the classic coat changes and intermittent lameness are enough for a positive diagnosis. However, equines in the early stages of the disease and those who don’t display classic symptoms require testing. The common Cushings test is a blood test that measures resting adrenocorticotropic hormone levels. This test is also used to monitor the disease once treatment starts.

The other common Cushings test, the Low Dose Dexamethasone Suppression Test, measures how much base-line cortisol is circulating in the blood, and how the animal responds to an administered dose of the cortisol suppressing steroid dexamethasone. Healthy horses will respond correctly to the steroid and show a drop in blood levels of cortisol. Those with Cushings won’t, and will continue to show high levels of cortisol in their blood stream.

TREATING EQUINE CUSHINGS

Cushings unfortunately is not curable but it is certainly treatable. Indeed, modern treatment regimes have allowed many Cushings positive equines to live fairly long and comfortable lives.

The usual Cushings treatment is the human Parkinson’s medication Pergolide. However, it needs to be supported by a careful maintenance routine that usually involves dietary changes, worm burden monitoring, regular hoof and dental work, routine vaccinations and so on. It may also be necessary to clip them in hot weather.