Stacking Medications May Cause Equine Health Problems to Stack Up, Too

When showing competitively, horse owners want their horses to feel and work at their very best for every practice and show.

For horses that may battle equine pain and inflammation, many horse owners turn to their veterinarians for nonsteroidal anti-inflammatory drugs (NSAIDs). However, each NSAID carries with it safety risks,¹ making them extremely dangerous when used simultaneously.

“I always ask that horse owners consult their veterinarian before administering any NSAID because they can be dangerous drugs when used improperly,” says Hoyt Cheramie, DVM, MS, manager, Merial Veterinary Services. “Still, many horse owners use NSAIDs to treat their horse’s pain and inflammation without the advice from a veterinarian,² so it is definitely possible for horses to experience an NSAID overdose or adverse reactions — and the risks only increase when using more than one NSAID at a time.”

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Beyond the health risks, stacking NSAIDs can take horses out of the game entirely. As the significant safety risks for horses were recognized, many equine organizations developed restrictions for NSAID use during competition. These regulations not only help to keep horses safe, but also remind horse owners of the risks of stacking NSAIDs.

The United States Equestrian Federation’s (USEF) Drugs and Medications Guidelines mandates that phenylbutazone and flunixin may not be used at the same time during competition and requires seven days’ withdrawal time from one NSAID before using the other.³ In addition, the American Quarter Horse Association (AQHA) considers it a rule violation if more than one of the organization’s approved NSAIDs are detected.

“Using multiple NSAIDs at one time can lead to serious side effects,”⁵ Dr. Cheramie says. “That’s why all products — plus breed organizations and competitions — generally have guidelines stating the length of time the drugs should be used and what drugs may be used in conjunction.”

However, Dr. Cheramie adds that, while most horse owners understand that NSAIDs carry with them certain safety risks, they may not understand that many NSAIDs have a similar mode of action.
“Traditional NSAIDs, like phenylbutazone and flunixin, work in similar ways,”⁵ Dr. Cheramie says. “So, if horse owners use bute to control pain and inflammation and then turn to flunixin before the bute has worn off, they are essentially giving their horse twice the dose and perhaps even leaving their horses exposed to potentially deadly side effects.”

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In fact, even when used alone, some NSAIDs can have adverse effects. For example, research has shown that just 7 or 15 grams of phenylbutazone — doses just four times higher than recommended daily levels — have been shown to cause death.⁶

Dr. Cheramie adds that it’s important to make sure horses aren’t exposed to peaks and valleys of pain relief — in addition to the possibility of an NSAID overdose. That’s why horse owners should look for an NSAID that can help alleviate pain while allowing horse owners to administer the drug once, rather than several times, a day.
Finally, Dr. Cheramie urges horse owners to talk to their veterinarians before using an NSAID.

“By keeping their veterinarian in the loop, horse owners can help keep their horses as healthy as possible,” Dr. Cheramie says. “As veterinarians, it’s our job to know how drugs will interact with each other and what the proper dosage should be for each horse. We can help ensure that your horse is getting the medication it needs without putting the horse in harm’s way.”

For more information, contact:
Michele Egan
Merial
(678) 638-3524
[email protected]

_{©2010 Merial Limited. Duluth, GA. All rights reserved. EQUIEQX938 (09/09).
1 – Merck Veterinary Manual. Ninth edition. 2005:2131-2135.
2 – Data on file at Merial. NSAID Use Survey.
3 – United States Equestrian Federation. Drugs and Medications Guidelines. 2007:2-3. Available at: http://www.usef.org/documents/competitions/2007/2007DrugsMedsGuidelines.pdf. Accessed June 1, 2009.
4 – American Quarter Horse Association. Show rules and regulations. Official Handbook of Rules and Regulations. 2009:130-132. Available at: http://www.aqha.com/association/registration/handbook.html. Accessed June 1, 2009.
5 – Reed SK, Messer NT, Tessman RK, Keegan KG. Effects of phenylbutazone alone or in combination with flunixin meglumine on blood protein concentrations in horses. Am J Vet Res 2006;67(3):398-402.
6 – MacKay RJ, French TW, Nguyen HT, Mayhew IG. Effects of large doses of phenylbutazone administration to horses. Am J Vet Res 1983;44(5):774-780.}