Some straight talk about phenylbutazone.

By Christine Hamilton in The American Quarter Horse Journal

Bute is a commonly prescribed anti-inflammatory drug.

Phenylbutazone, or “bute,” belongs to a class of therapeutic medications called nonsterodial anti-inflammatory drugs, or NSAIDs. Aspirin and ibuprofen are other common drugs in this class. Like asprin, bute reduces inflammation and fever and also acts as an analgesic, or pain-reliever. It’s also one of the least expensive horse medications on the market.

The American Quarter Horse Journal talked with two veterinarians about their opinions on bute. Dr. Jerry Black is a former president of the AQHA educational marketing alliance partner American Association of Equine of Equine Practitioners. Dr. Noah Cohen is a professor in the department of large animal clinlical sciences at Texas A&M University.

Both Drs. Black and Cohen emphasize following your veterinarian’s guidelines when administering bute (or any medications) to your horse.

How Does Bute Work?
Bute works to reduce inflammation by blocking the effects of prostaglandins, a large group of hormones that act on the body in many ways, including mediating inflammatory response. Bute primarily inhibits an enzyme called cyclo-oxygenase (COX).

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“The COX enzymes metabolize arachindonic acid (a component of the cellular wall) into molecules called eicosanoids. Eicosanoids include prostaglandin molecules,” Dr. Cohen explains. By inhibiting COX enzymes from metabolizing prostaglandins, bute reduces the body’s ability to produce inflammation.

When Do You Prescribe Bute, and What Is in the Typical Dose?
Dr. Black most often prescribes bute to treat chronic pain.

“We have found bute to be very helpful where there is chronic inflammatory process,” he explains, “such as in the (possibility of) long-term bute use.”

When using bute for a long period of time, Dr. Black steadily reduces the dosage amount administered to the horse. While the amount of bute depends on the horse, he describes a typical treatment plan.

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“Typically, we’ll start with three grams of bute a day, split between morning and evening over a period of about five days. … Then we’ll decrease that down to two grams a day. Depending on the horse, we might do that for a longer period, maybe 10 to 15 days. … We’ll drop it to just one gram a day after that.”

Dr. Black has seen bute greatly improve the quality of life for horses living with persistent pain.

“We’ve had chronic laminitic horses living on a gram of bute a day for months, even years.”

What Do Horse Owners Commonly Misunderstand About Bute?
Oddly enough, in Dr. Cohen’s opinion, the most common misunderstandings seem to be polar opposites.

“People fail to recognize the risks of phenylbutazone and assume it’s perfectly safe,” he says. “They don’t understand that, although very rarely, horses can become very sick after administration of bute for even a brief course of treatment.”

Ulcers are a more common reaction horses can develop over time. “If they develop ulcerations,” Dr. Black says, “they might have weight loss or poor hair coat, or show repeated mild signs of colic. When that happens, the first thing we do is take them off medication.

“Then we will commonly use an anti-ulcerative medication like omeprazole (GastroGard) concurrently with the bute,” he says. Even if a horse doesn’t have ulcers, Dr. Black will prescribe GastroGard as a precaution.

“On the other hand,” Dr. Cohen continues, “people also overestimate the risks. They fail to understand that nearly all treatments carry a certain amount of risk, including bute.” Some horses may react strongly to bute, while others may tolerate it over long periods of time.

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How Do You Prescribe Bute for Performance Horses?
“We follow all of AQHA’s guidelines in prescribing bute at competition,” Dr. Black says. “Fortunately, most of the performance disciplines now recognize that it is a therapeutic drug, and it’s beneficial to our horses. Beneficial not only for the ones that have minor, long-standing problems, but even for the younger horses that are working hard over several days. The stress level on a horse at competition, in terms of the amount of work required of them, is higher than when they’re in training.

While bute is permissible under AQHA rules (see the AQHA Handbook section 441) it is important for any horse owner to be familiar with the particular guidelines for any medication.  There are other useful alternatives to bute – one is Equioxx which due to its safety profile is permitted for longer-term use during AQHA events.

Dr. Black has found that bute can be especially helpful for the kind of horse he affectionately calls “the old campaigner,” who might have minor aches and pains that might be associated with such conditions as arthritis.

“I use bute in the case of the good, solid show horse that’s a non-pro, amateur or youth horse, and might have something like navicular disease,” he says. Bute can enable those horses to enjoy competing on the weekends, pain-free, extending their performance careers.

“We need those seasoned horses in the industry, there’s no question about that,” he says. “They’re the horses that teach our amateurs and youth kids how to ride. I’m 58 years old and often have to have a little Advil in order to comfortably ride my cutting horses.

“With a standard bute dose, you’re not supplying enough analgesic to make a horse that’s really hurting – or injured – sound,” he continues. “But you are providing a therapeutic level for any minor sorenesss they might have and helping them to perform pain-free. Nonsteroidal medications, like bute or Banamine, can be very therapeutic in those cases. They help our horses, and that’s important to all of us.”