Phenylbutazone (bute) is an extremely useful and practical prescription drug that is commonly used in equine veterinary practice. Bute has been around for decades and is very effective for a variety of conditions, especially those involving the musculoskeletal system. It is also used (less often) in other species.

Bute is somewhat less effective than Banamine® (flunixin) in treating abdominal pain (colic), but it can still be useful.

Bute is supplied in pastes, powders, and tablets. In addition, Bute may be given as an intravenous injection.

Bute is in the same drug class as ibuprofen, flunixin meglumine and acetaminophen, the so-called NSAIDS (non-steroidal anti-inflammatory drugs), which work by reducing the formation of prostaglandins, a group of molecules that take part in inflammation. The inflammatory pathways also lead to swelling and pain. By reducing prostaglandin formation, pain and inflammation (swelling and redness) is decreased also.

However, there are a number of "good" or "housekeeping" prostaglandins that perform protective functions in the body. Bute eliminates these also, and this exposes certain body systems to injury. The two organs in horses that tend to be damaged by NSAIDS are the intestine and the kidney.

Although this drug requires a vet’s prescription, many horse owners keep a tube of bute handy to treat their horses when they see signs of lameness, swelling or less commonly abdominal pain (colic).

The problem is that horse owners often do not understand the benefits and limitations of this drug, and/or do not know what the underlying diagnosis is that they are treating. As a result, horse owners may use this drug inappropriately, and this can be life-threatening to a horse.

At minimum you should consult with your vet before you administer this drug to your horse. Depending on the problem, your vet may need to examine your horse, they may prescribe a different treatment, or they will provide you with careful guidelines for the use of bute.

In colic cases, bute may appear to resolve the problem, giving horse owners false confidence as the disease process continues or worsens. It is true that bute may help to resolve a simple spasmodic or "gas" type colic, but it may only provide temporary relief in more complicated or severe cases.

On numerous occasions, I have been called by a horse owner that thought bute “fixed” the colic, but their horse returns to pain after it wears off or, even worse, they find their horse dead the next day. This warning applies even more to Banamine®, which is more commonly used by horse owners without veterinary guidance in cases of colic, and carries even greater risk of masking a problem.