Wednesday, Apr. 17, 2024

A Healthy Respect For NSAIDs

Years of experience have given this veterinarian reason to look twice at the use of multiple NSAIDs.

Many years ago, when I was a relatively new veterinary graduate, I was called on a Monday morning to see a nice, young show hunter that had been discovered to have a “big knee.”

Upon examination, I found the horse to have moderate heat and swelling with pain on flexion of the left knee. He demonstrated a 3/5 lameness to trot in hand (American Association of Equine Practitioners scale, head bobbing).

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Years of experience have given this veterinarian reason to look twice at the use of multiple NSAIDs.

Many years ago, when I was a relatively new veterinary graduate, I was called on a Monday morning to see a nice, young show hunter that had been discovered to have a “big knee.”

Upon examination, I found the horse to have moderate heat and swelling with pain on flexion of the left knee. He demonstrated a 3/5 lameness to trot in hand (American Association of Equine Practitioners scale, head bobbing).

The suspicion on the part of the trainer was that the horse must have gotten cast in the stall because it was normal the day before when it was schooled. I suspected a severe contusion (bruise). I suggested it would be wise to radiograph the knee, but the owner initially declined this.

I administered a 500mg dose of Banamine® (flunixin meglumine), a relatively new drug at the time, and a 20mg dose of Azium® (dexamethasone), told them to ice and poultice the knee and hand walk him only for exercise. I dispensed four packages of Banamine granules for the horse to receive over the next two days at a rate of one package twice daily.

Two days later, when I returned to check on the horse, the swelling in the carpal region (knee) had subsided remarkably, and the horse was trotting soundly. He was, of course, still getting Banamine orally, so I instructed the trainer to stop with that morning’s dose. Everyone was quite eager to ride the young horse again as they wanted to show on the weekend.

I encouraged them to be patient about working the horse just yet because I did not have a comfortable feeling about the analgesic potency of the medication the horse was receiving. I admitted that I was probably being over cautious, but they agreed to my request. I asked that they give me an update on his soundness the next day.

Thursday afternoon I received a call that he was once again lame. I recommended continuing to ice the horse and keep him confined, and that I would be there first thing Friday morning to examine and radiograph him (this time they agreed).

Upon my examination on Friday morning, I once again found the horse to have some heat and mild swelling in the upper portion of the left carpus and to be again 3/5 lame. We performed radiographs and recommended again putting the horse on Banamine orally and continuing supportive care. I suggested that the horse be confined with no exercise until I had a chance to develop the radiographs (I now thank heaven for digital radiography!).

Well, when I got back to the office and developed the images, I was expecting something like a small chip or just a lot of edema under the skin, but to my surprise, there was a spiral fracture of the radius (forearm) from the radial-carpal joint at the knee to the elbow! This horse was sound on a U.S. Equestrian Federation legal level of Banamine (although I will admit that it was being split into twice daily doses). Had I allowed that horse to work on Wednesday when it appeared normal or had allowed it to just remain on medication, a serious disaster would have no doubt occurred.

As things turned out, following consultation with Dr. Bud Fackleman at Tufts University (Mass.), we simply confined the horse for three months, and all healed well with no surgical intervention. Needless to say, I was left with a healthy respect for the analgesic potency of Banamine.

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A Useful Purpose

Banamine (flunixin meglumine) is a non-steroidal anti-inflammatory drug that reduces inflammation and the pain associated with it by suppressing the chemical mediators of the inflammatory reaction. It is but one of several NSAIDS available for use in the horse.

Inflammation can occur from acute trauma or from more chronic wear and tear. Suppressing inflam-mation may actually have a disease modifying effect and be good for the patient. These drugs do not work on the central nervous system and suppress sensation or perception. Horses on NSAIDS are not really “doped.”

The USEF has long supported a therapeutic medication rule intended to protect the welfare of the horse by allowing horses in competition to receive medication for specific medical conditions that will not seriously affect their performance or be a threat to their welfare. This is a good rule because it has allowed for suddenly sick horses to be appropriately treated with specific medications, recover and still compete. Mildly arthritic horses have still had a useful purpose when made comfortable. Under this rule such horses are not in violation of medication regulations.

It has been the opinion of the USEF veterinary committee that if such horses are otherwise normal, then they should be allowed to compete. Because of the common use of NSAIDs many horsemen have become complacent about the relative potency of these medications. We also have to factor in the horse’s pheno-menal ability to overcome discomfort and function well athletically despite musculoskeletal pain.

In the later 1980s the veterinary profession recognized that the combination of phenylbutazone and flunixin meglumine was extremely potent as an analgesic combination and that perhaps horses that were too seriously injured might appear to be sound enough to compete. At this same time, it was also being recognized that this combination of medications carried the risk of serious damage to the gastrointestinal tract and possibly the kidneys.

As a result, USEF banned the use of “Bute” and Banamine in combination, but did allow the concurrent use of either one of these drugs with other approved NSAIDs, i.e., naproxen, meclofenamate, and ketoprofen. There was not substantial evidence that other combinations of NSAIDs posed as much risk. There was a concurrent concern among horsemen that older “campaigners” might need a little more help for chronic arthritis than was offered by one NSAID.

Significant Side Effects

I had the opportunity in my veterinary practice during the 1990s to begin performing many gastroscopies in adult horses because of complaints of colic and poor performance. We found greater than 63 percent of the hunters, jumpers and dressage horses that we examined had equine gastric ulcer syndrome. This work was published by my practice in 2001.

It was not uncommon that many of the horses we scoped had been receiving various NSAIDs for competition. Our concern was again raised that NSAIDs of any type (especially in combinations) may contribute to the development of EGUS.

During the same time period, we were also recognizing mild to moderate colon problems more frequently and wondered if some of this was related to NSAID use. Certainly we knew that high doses of phenylbutazone could cause colitis, but there was not much else published to implicate other anti-inflammatories.

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It has subsequently come to light that combinations of NSAIDs do have an additive effect related to the inhibition of certain enzymes. Some of these enzymes help maintain the health of the stomach and intestinal lining or “mucosa.” When the enzymes are inhibited, the protective mucous coat is reduced, and the mucosa is more vulnerable to erosion and ulceration from acids and other irritants. Combinations of NSAIDs inhibit mucosal protection and increase the susceptibility to ulceration. Ulceration leads to poor appetite, poor function, poor performance and colic.

A number of years ago, when I was the chairman of the veterinary committee for the USEF, we proposed a one NSAID rule to the general membership out of welfare concerns for the competitive horse. Our committee was concerned that the “Bute-Banamine” combination was but one of several potent and potentially dangerous combinations that horses were “legally” receiving prior to and during competition. We were ahead of our time because we did not have as much data as we now have to substantiate our concerns. This proposal was not approved and understandably so.

Now, again, the concern for multiple NSAID use is on the rise, and horsemen need to know that the frequent use of such combinations is a real health hazard. The AAEP has officially gone on record as recommending the use of only one NSAID for therapeutic use in non-racing performance horses.

I would ask the skeptic to tell me when was the last time his doctor put him on a combination of NSAIDs for a musculoskeletal problem? It’s not done because of potential toxicity.

Let’s pause to reflect on the example I gave at the beginning of my discussion and realize that these meds are really quite potent when properly dosed.

I see many horses that “just aren’t good enough on one medication” that are, in fact, not being adequately dosed. Body weights are underestimated, and the appropriate dose of one medication is not being administered. I see few horsemen and owners take advantage of the fact that oral phenylbutazone can be dosed twice daily per USEF regulations and works better that way! Same goes for meclofenamate (the old “Arquel”).

If medications were used correctly, one medication may well be just fine. From a welfare standpoint, we must ask if it’s justifiable to give two drugs. Horsemen and animal advocates alike should ask, “If the horse needs that much medication, should he be competing?”

Maybe we need to revisit the diagnosis, if there is one. There’s supposed to be a diagnosis for these horses to be receiving the medications per USEF rules. Perhaps we need to re-examine why we are still trying to make this horse compete.

There is a new medication now approved for use in horses and listed as not prohibited by USEF called firocoxcib (Equioxx). This is a newer “COX-2” inhibiting NSAID that has less effect on the gastrointestinal tract when properly dosed than the older primarily “COX-1” inhibiting NSAIDs. It certainly offers some hope for horses that seem to have a problem with more traditional NSAIDs. There would appear to be a considerable margin of safety related to gastric ulceration or colitis, and analgesic efficacy is acceptable. How this medication will “catch on” remains to be seen.

Horsemen and veterinarians need to re-examine their current practices and look at the current trends in medication of the show horse. Certainly, the vast majority of show horses are not receiving double NSAIDs if any at all, but there are some that do.

Some stables routinely medicate horses to show in a regimented fashion with pre-determined drugs that the trainers, owners or veterinarians feel they need in order to compete at their best level. In some instance they may be correct, but in many it’s just done because of fear of not doing enough and not keeping up with the competition. Sometimes enough may be too much, especially when done frequently, in the case of double NSAIDs. 

Richard D. Mitchell DVM


Rick Mitchell, DVM, received his veterinary degree from Oklahoma State University. He has served as the official veterinarian to the U.S. Equestrian Team for the Pan American Games, World Equestrian Games and the Olympic Games and is on multiple Boards of Directors, including the USEF, the Connecticut Veterinary Medical Association and the American Association of Equine Practitioners. He has served on advisory boards for Boerhinger, Pfizer and IDEXX Pharmaceuticals.

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