Phenylbutazone (bute) is an analgesic (pain reliever) and a non-steroidal anti-inflammatory (NSAID) that is commonly used for the treatment of lameness, and to treat pain and swelling in horses.
In some cases, it can be difficult to determine whether a change in behavior (usually under saddle) is due to pain or is strictly behavioral in nature.
The preferred approach to determining this is for a vet to do a thorough physical exam, a lameness exam and even an examination of the horse doing its job under saddle. After this evaluation, they will likely have a sense that lameness or pain is involved, or not. They may suggest that other diagnostics be used to further rule out problems.
In some cases, I recommend horse owners put a horse on a short course of phenylbutazone, what I call “a bute trial” as a diagnostic. This is performed in our practice when there is a question as to whether pain plays a role in performance related limitations or problems.
In some cases, I will suggest to a horse owner that they perform this test before I see the horse. In other cases, I recommend it after an initial exam, particularly if there is still a question about the nature of the problem.
Establish an objective baseline before you give your horse bute by asking them to perform the maneuvers and patterns that are problematic. Evaluate your horse's response carefully and objectively. Do this over 2-3 days, being as consistent as possible.
Then administer bute to your horse (2 grams once, then 1- 1.5 grams every 12 hours for 3-4 days for an average 1000 lb horse). Ride precisely the same maneuvers and patterns during this time and determine whether there is any improvement in your horse's performance.
Keep in mind the power of the placebo effect when you do this. Even if you are as objective as you can be, there is still a chance that you can be mislead.
If there is objective improvement, the problem is likely pain-related and an examination is additional diagnostics provided by your vet are advised.
Tips for safety & Success
Do not perform a bute trial without involving your vet, who can ensure that this trial is performed properly and the results are objectively verifiable.
Likewise, if your vet is involved from the outset, they are in a better position to recommend proper treatment for a variety of conditions that cause lameness.