Tuesdays with Tony


Recently the hunter/jumper world was up in arms. A drug named Medroxyprogesterone was banned from competition horses. I asked my humans, why all the fuss? The answer was a complicated one. Read on for my take on mares, drugs, and the horse show world.

What’s It Do, Anyway?

Medroxyprogesterone is the name of the drug in Depo Provera, a human birth control injection. Why do horses need birth control injections, you ask? Me too! I mean, I had some ideas about why horses would need birth control, but my Docs told me it doesn’t even prevent pregnancy in horses. This left me completely stymied. Why give it to them? Medroxyprogesterone is thought (thought, I say, it’s not proven) to act on receptors in the brain which make horses feel calm. Medroxyprogesterone was being used for that effect, not keeping mares out of heat (which it doesn’t do, anyway), or minimizing stallion behaviors (which it also doesn’t do). It now made sense to me why it was banned. It’s thought to be a calming drug, and that’s a big no-no in horse shows. Again, I was told it’s more complicated than that. Gawd, you humans are a complicated lot!! Be more like cats. I want food, and I want the door to open when I ever-so-politely request it. Simple.

The Problem

Medroxyprogesterone is most often given to horses in the form of a compounded drug as an injection. Compounded drugs are their own very special can of worms. Compounding is the custom mixing of a medication into a different concentration or form. For medroxyprogesterone, this means making it more concentrated for the horse world. The biggest problems with compounded medications are consistency and sterility. If it’s an oral medication with a big range of dosing tolerance, then this is okay. However, for medroxyprogesterone, it’s an intramuscular shot, and that’s a big deal. In the recent past, multiple horses dropped dead immediately following injections. Now, this could be an individual horse’s reaction to the medication, or it could be a problem with the compounding process. Either way USEF, the organization that regulates hunter/jumper shows, said we weren’t so sure about this medication anyway, so we’re taking it off the table as a legal medication.

Springhill Equine Veterinary Clinic

The Human Side of the Problem

Based on this discussion, I wasn’t clear on the problem. It seemed to me that it was fine if this drug was gone. Everyone knows calming drugs like this aren’t allowed. Add to it that horses died. Why all the fuss? Because humans, that’s why. You humans are such a gullible, overly competitive lot. I’m pretty sure if I told you I could wave my left paw in front of your horse and they wouldn’t spook anymore, and they’d never need to be ridden, or lunged, and they’d walk in the show ring calm as a cucumber, ready to perform, you’d be lining up to pay me money. As an aside, should you ever feel the need to do this, I’d prefer cat food over money. Anyway. This drug was a hoped-for shortcut for most people using it. For others, the simple belief in its mystical powers caused their horse to behave better. Maybe we should give the humans the calming drugs……

But the simple truth is horses take time to train. And sometimes they see dragons in the woods. Sometimes plastic bags are scary. Unlike basketball or football, you guys are in a sport where the ball has a mind of its own. 

But My Mare is Horrible When She’s in Heat!

There are definitely those mares. We have a great drug for those mares with a proven track record: Regumate. You shouldn’t touch it with your bare hands, but that’s what gloves are for. If your horse is in a situation where a daily oral medication is tough, there is a long-acting shot version that lasts for a month. And this one really lasts. It has research behind it to show that it suppresses heat cycles, or maintains a pregnancy, depending on which goal you are going for. If your mare is awful all the time, even when she’s not in heat, then that’s the mare you’ve got. I hate to be the bearer of bad news, but no amount of medication is going to fix that. Removing the ovaries is also unlikely to fix it, unless it’s only a problem when she’s in heat. In this case I recommend finding a really good trainer, and practicing your patience. But then, with horses, that’s never a bad idea. 

Horses are tricky critters with a mind of their own. Accepting that at the start of the adventure will make you much happier with the outcome. Trying to find the right drug to create your perfect horse rarely works. Practicing patience and remembering that your horse’s life goals may not be the same as your life goals is key. Take some training advice from this wise cat: when things aren’t going the way you want them to, take a nap.

Until next week,


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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