While Dr. Lacher was off gallivanting at the Grand Canyon last week, I was helping Dr. Vurgason groom her horse for the Racehorse Reclaim benefit horse show. As we were brushing his coat to a glorious shine, what to my wondering eyes should appear but a clump of long hair! I couldn’t believe my eyes: Smokey was already beginning to grow his winter coat. “Is this normal?” I inquired to Dr. V. She replied that yes in fact, a horse’s winter coat begins to grow in response to hormonal changes within the brain. These hormones are triggered by changes in length of daylight.
You may have noticed your evening rides being cut short recently because it is getting dark by 8:00 already. Well, horses have noticed this too. The brain actually has a very intricate system of glands that produce hormones that stimulate other glands that produce other hormones that stimulate organs elsewhere in the body.
That long hair coat comes way too early for Florida. It makes for some hot horses. In particular, if your horse has heaves (asthma in horses), or is a non-sweater, this time of year is no fun. Unlike me, your horse likely can’t come in to the air conditioning to get out of the heat. This means it’s time to fire up the clippers and get rid of that hair. Sometimes that hair can be an indication of a problem.
Long hair at the wrong time of year can mean one of the glands in charge has gone AWOL. In horses, the pituitary gland is the most likely culprit. Nobody knows why, but many older horses will grow a tumor on their pituitary gland called an adenoma. This tumor applies pressure to the gland as it grows, and causes it to over-produce its hormones (namely, adrenocorticotropic hormone, or ACTH). This condition is known as Pituitary Pars Intermedia Dysfunction, or more affectionately, Cushing’s disease.
Cushing’s disease can lead to a whole slew of problems. For one, overproduction of ACTH can confound the whole winter-coat-growing system, so your horse winds up with long, curly hair in the hottest summer months. Failure to shed out completely or patches of long hair (not in the Fall) are often early signs of Cushing’s disease. Through mechanisms which are not completely understood, Cushing’s disease can cause lethargy, muscle loss, potbellied appearance, fat deposits, laminitis, and recurrent infections. Hmm, maybe I have Cushing’s disease…?
Luckily, our Docs have ways to determine if your horse’s long hair is from Cushing’s or if they are just getting ready for winter. First they draw some blood, then it goes on a trip to Cornell University where they test the ACTH levels. When I was a kitten, ACTH levels couldn’t be pulled in the Fall since the levels go up in the Fall and the humans didn’t know what was normal and what wasn’t. They have fixed that problem with some research. Now Fall is a great time to test since horses who are just beginning to show signs will have really high levels in the Fall. Also….Springhill Equine has a contest going on now where you can get your horse tested for FREE!!!! Free you say? Yep, FREE. Just click on this link to the “Does my horse have PPID?”
form, fill it out and Voila! You are entered. That’s easier than getting Beth to share her tuna fish sandwich with you.