Non steroidal anti-inflammatory drugs are probably the most commonly used drugs in horses with joint disease. These drugs, called NSAIDs, are classified in this manner to separate them from anti-inflammatory drugs that are steroids, including all the cortisone compounds. The most common NSAIDs used in horses are phenylbutazone (called bute), banamine, and Equioxx. Dr. Michael Rose from the University of Pennsylvania reviewed all these medications and indicates they all work in basically the same manner: by inhibiting an enzyme called COX. There are two types of COX enzymes in the horse’s body, which are called COX 1 and COX 2. COX 1 is a good enzyme that is important for multiple body functions while COX 2 is an inflammatory enzyme so ideally the perfect drug would block COX 2 to stop pain and inflammation but not block the good enzyme COX 1.
The most commonly used drug, bute, blocks both of these enzymes and can cause toxicity in some horses. However, it is the least expensive of the drugs and if used correctly, can be very effective and safe. Banamine also blocks both enzymes and although many people feel it is safer than bute, it does not last as long, is less effective for joint pain, and is much more expensive. Equioxx is a newer NSAID that selectively blocks COX 2 much greater than COX 1, so it should be much safer than bute and banamine. It seems Equioxx would be much preferred for long-term treatment but it is labelled for only 14 days of use, whereas bute has no restriction on length of use. Equioxx is effective but much more expensive than bute. However, it may be useful especially in horses that are sensitive to bute. Ask your vet about using these NSAIDs and only use them as your vet prescribes as all of them can cause side effects.