From Endurance to Dressage
A Cushing's Tutorial
So what exactly is Cushing's Disease? Until a few weeks ago, I only knew that it was a disease that mostly affects older horses with symptoms that include long shaggy coats, pot bellies, and problems with hooves. Sort of like this guy.
Very simply - or not, Cushing's Disease, also called Pituitary Pars Intermedia Dysfunction (PPID), is a disfunction of the pituitary gland. Over time, the pituitary gland becomes over-enlarged and produces too many hormones. Not good. Ask any woman approaching 50 (cough, cough) what it feels like to have your hormones go out of whack.
In particular, horses with PPID produce too much of the hormone called the adrenocorticotropic hormone (ACTH). High levels of ACTH cause an over-production of cortisol. And since hormones have effects on many different organ systems, increased cortisol creates a variety of symptoms like:
So who gets Cushing's Disease? According to the AAEP, "the average age of horses diagnosed with PPID is 20 years, with over 85 percent of the horses being greater than 15 years of age. Although most common in aged horses, PPID has been diagnosed in horses as young as seven years of age."
I think you can see where all of this is heading. Speedy will be 15 in April. Speedy has never before had an abscess, yet in the past few weeks he's had not one, but two. My vet decided we needed to check for Cushing's Disease.
There are several ways to test for Cushing's: 1) the dexamethasone suppression test and 2) the measurement of resting plasma ACTH concentration. However, one thing to note is that the time of year the tests are done can affect the results. In the fall, horses naturally increase the production of a variety of hormones as the body prepares for winter. Fortunately for Speedy, January is a great time to check ACTH concentrations.
A normal ACTH concentration is somewhere between 10 and 50. Speedy's ACTH level came back at 56, just outside of the normal range. Some horses can have numbers above 1,000. A lot of things can affect that score - time of day, when the horse last ate, and so on. Even though Speedy's ACTH level was very close to normal, Dr. Tolley felt that it would be prudent to put him on medication.
Here's where most owners cringe and ask, "What's that going to cost?" I almost find it funny that Speedy needs a daily medication as I had just this month decided to take my boys off ALL supplements. Joke's on me I guess. The only FDA approved medication for Cushing's Disease is pergolide, brand name Prascend.
I bought Speedy's first box of 160 tablets from a friend who no longer needed it. When that box runs out, I'll need to reorder from somewhere like Allivet as Prascend is available by prescription only. It's per day cost is right around $1.75. Prascend is actually cheaper than the Platinum Performance was, so I can't complain too much.
There is a glitch of course. Pergolide is on US Equestrian's prohibited substance list. Don't even get me started on how incredibly stupid my vet found that rule. One of the worst things you can do for a Cushing's horse is to stop and restart pergolide every other week during show season.
There is good news though. As of December 1, 2018, US Equestrian will now allow pergolide if the horse has been granted a Therapeutic Use Exemption (TUE). An explanation of the rule change can be read here.
I've already applied for a TUE, and my vet has submitted all necessary paperwork. When I phoned US Equestrian, the woman I spoke to had no idea how long it takes to be granted a TUE. She said that a panel must review my request. Way to go, US Equestrian. No timeline or answers make me feel great.
So that's it. Speedy now has Cushing's Disease which means daily medication, annual bloodwork, and of course getting that pesky TUE. Dr. Tolley wasn't too concerned and neither am I. There's just no cure for getting old.
1/28/2019 08:08:47 am
Hopefully that was just a seasonal glitch and Speedy is otherwise OK, but ping me if there's anything I can help with. Taran has Cushings (his ACTH was over 900 lol) and it can be challenging to manage in a sporthorse, but doable. At least we can now apply for a TUE - we couldn't before now, and it was really hard to take them off Prascend for a few days for competition.
1/31/2019 05:15:00 pm
Thanks, jenj. I am not worried about it at all - my vet is pretty unexcitable, but I thought of you immediately when my vet gave me his report. I will definitely touch base if I need some advice - or moral support! I already got my TUE which was faster than I expected.
1/28/2019 02:43:03 pm
Sorry to hear about Speedy! Prascend is a fantastic drug, I had great results with my Arab mare. I lost her last year at age 29 and she was sound and energetic until the very end!
1/31/2019 05:16:16 pm
Thanks for the encouragement, Breanna. So far, I am unconcerned as Speedy is without symptoms. No sense is borrowing trouble. :0)
Patti Strauch, DVM
1/28/2019 07:03:16 pm
I feel your pain. We had 3 oldies at one time with it a few years back. It seems to hit them just when they are getting seasoned and reliable. The Prascend is very water soluble& dissolves quickly. It can be put in a 3 cc syringe and given orally.
1/31/2019 05:19:16 pm
Thank you, Patti! It took a few days to figure out how to best give it to Speedy. He gobbled up the treat the first two days and then became convinced that the ranch owner was trying to poison him. He started refusing all treats from her. I finally just showed her how to pop it in his mouth with a peppermint chaser. The pill is so tiny that it sort of stuck to his tongue. And since he loves peppermints, he forgot about the pill and zoned in on his treat. Love it when we can trick them. LOL
I'm sorry, it's a hard diagnosis to hear. Eminently manageable, but it's tough to feel like they have this "old horse" thing.
1/31/2019 05:23:48 pm
Many thanks, Amanda. I HATE reading about all of the MANY things that MIGHT go wrong, so I will definitely avoid that particular rabbit hole. And like you, I trust my vet completely and will follow his advice every time. It amazes me how many people dole out advice when I've already shared what my highly educated, VERY experienced vet has recommended. Do they think I'm going to follow the advice of someone who thinks they saw something work one time 14 years ago over my vet who has a LICENSE to practice medicine? LOL
2/2/2019 11:36:22 pm
No. It is their way of giving support and encouragement.
2/10/2019 08:52:16 am
Maybe so Miriam, but there are times when the advice is uneducated. Some people want to *insist* that you try their idea, and when you decline, they act as though you're being unreasonable and stupid. I've found this particularly true while dealing with my migraines. You wouldn't believe the weird suggestions I've received even after explaining what my neurologist has said about that particular treatment. But yes, you are right. Most people really just want to show their support. I just wish they could offer a hug or a sympathetic "man, that sucks." instead. :0)
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About the Writer and Rider
I am a lifelong rider.
I began endurance riding in 1996 where I ultimately completed five, one-day 100 mile races, the 200-mile Death Valley Encounter, and numerous other 50, 65, and 75 mile races. I began showing dressage in 2010.
Welcome to my dressage journey.
About Speedy G
Speedy went from endurance horse to dressage horse. After helping me earn a USDF Bronze medal in the summer of 2020, he is now semi-retired. Speedy is a 2004, 15'1 hand, purebred Arabian gelding. His Arabian Horse Registry name is G Ima Starr FA.
Izzy was started as a four-year old and then spent the next 18 months in pasture growing up. I bought him as a six-year old, and together, we are showing at the lower levels. He is a 2008, 16'3 hand warmblood gelding. His Rheinland Pfalz-saar International (RPSI) name is Imperioso.
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