Tuesdays with Tony


There is an interesting phenomenon that seems to strike around this same time each year amongst the horses I see: they get hairy. Despite the consistency and repeat-ability of this syndrome, owners seem to worry every time this happens. What do they worry about, you ask? PPID. Affectionately known as Cushing’s disease, Pituitary Pars Intermedia Dysfunction, or PPID, is a disease primarily seen in senior horses. One of the many signs of this disease, and undoubtedly the most familiar sign to horse owners, is a long, shaggy hair coat. So, is your horse’s winter coat normal, or does he actually have PPID?

Let’s Review

   Why should you care if your horse has PPID anyway? Well, what if I told you your horse has a brain tumor? That’s a little scarier. PPID in horses is in fact caused by a tumor pressing on the pituitary gland in the brain. As the tumor grows, it causes the pituitary gland to overproduce certain hormones. These hormones can cause a myriad of problems when their levels are elevated. Problems such as laminitis, inability to fight off infections, weight loss, lethargy, and abnormal hair coat are commonly seen.
    The most concerning, even life-threatening, consequence of PPID is laminitis. There is no treatment for laminitis, and the damage caused by laminitis is irreversible. This is why preventing laminitis by treating the underlying PPID is so important.
    If you have a senior horse with PPID, you may not even realize there is anything wrong. On numerous occasions I have overheard an owner tell one of our docs that their horse acts 10 years younger since beginning treatment for PPID. Since lethargy, chronic infection, and weight loss are common clinical signs of this disease, it is not surprising that horses feel a whole lot better once their symptoms are properly managed.
    To tell you the truth, the classic long, curly hair coat is actually an advanced sign of PPID. Early signs include a change in attitude, decreased athletic performance, loss of top line, and slightly delayed shedding. Vets are trying to get better about recognizing these subtle, early signs, so that testing and treatment can be initiated sooner, and the more severe signs and effects of PPID can be prevented.

Let’s Test

   So let’s pretend it’s fall and your horse went ‘poof’ and blew out a long, winter hair coat seemingly overnight. Does he have PPID? Before making the diagnosis, our docs are probably going to ask you a few questions.
    First, is this normal for your horse? If he has been blowing out a shaggy winter coat on September 1st every year since he was 3 years old, it may be normal for him. Is his hair coat relatively even over his entire body? The abnormal hair growth associated with PPID is often patchy at first, found initially on the back of the lower limbs. Is the hair straight, or is it long and curly? A horse with a thick, long, curly hair coat covering his entire body has about a 90% chance of having PPID. Does he shed out completely in the spring? Some horses just grow thick winter coats; as long as they shed out completely at an appropriate time each year, they may be completely normal. Have you noticed any other signs? While many of the signs of PPID are somewhat non-specific, it is very common for horses to exhibit more than one. Does your horse have recurrent hoof abscesses, and you’ve also noticed he’s been losing weight recently? Has your horse been a bit slugging under saddle recently, and he also took forever to get over that eye infection he had earlier this year?
   If any of these scenarios sound like your horse, or if your vet suspects that your horse may have PPID, I really recommend that you have him tested. Did you know that there is a simple, one-time blood test that is highly accurate for diagnosing PPID? A baseline ACTH test is all that is needed; no stimulation testing, fasting, or dexamethasone suppression testing required! Did you also know that based on recent research you can test your horse for PPID any time of year? That’s right, there are now scientifically established reference ranges based on season that account for the normal rise in ACTH seen in horses in the fall.
    We now know that many of the signs we used to associate with “normal aging” in horses are actually signs of PPID. And better yet, this means they can be treated! So, ask your vet about testing for PPID at your next wellness visit.

Let’s Treat

   We are fortunate that there is an extremely effective, safe, and easy treatment available for horses with PPID. Prascend (the brand name for pergolide) is a tiny pink tablet you can readily hide in your horse’s grain every morning. Since the medication mimics a hormone naturally found in the horse’s body, side effects are very rare and mild. The best part about treating with Prascend is the results! I have been surprised again and again with the positive difference I’ve seen in horses that come through the clinic before and after starting treatment. And by starting treatment early, you can prevent the development of those advanced signs of PPID including laminitis, tendon and suspensory ligament breakdown, and recurrent infections.
     A rare but recognized side effect we sometimes see with Prascend is horses not wanting to eat their feed with the tablet in it. Lucky for you though, I have come up with some creative tips and tricks to address this issue: First, try splitting the dose into 1/2 tablet morning and night, rather than a whole tablet at once. If that doesn’t work, we can even try going to 1/2 tablet once a day, but we would want to re-test your horse after a few months to make sure his hormone levels were controlled at this dosage. If your horse simply refuses to eat his grain with even a partial tablet in it, try feeding his tablet in a soft treat like a stud muffin. You can also try enticing your horse to eat it with molasses or applesauce on top of his grain. Yummy!
   So now that you know why it’s important to know whether your horse has PPID, how and when we can test them, and how easy it is to treat them, what do you think? Is your fuzzy horse just gearing up for the coldest winter of the century, or might there be something more going on? Call me at the clinic to schedule your horse’s ACTH test, and let’s see if it’s PPID!
P.S. Are you craving more horse knowledge? Check out the podcast that my docs make, Straight from the Horse Doctor’s Mouth. You can learn a lot in a half hour listening to them talk about various horse things. It’s pretty amazing, even to this cat, and I’m not easily impressed.
Springhill Equine Veterinary Clinic

Tuesdays with Tony is the official blog of Tony the Clinic Cat at Springhill Equine Veterinary Clinic in Newberry, Florida. If you liked this blog, please subscribe below, and share it with your friends on social media! For more information, please call us at (352) 472-1620, visit our website at SpringhillEquine.com, or follow us on Facebook!

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