Jinx had always had a sensitive stomach. He had his first bout with gastric ulcers as a weanling, when the stress of leaving his dam combined with dietary changes triggered the painful erosion of his stomach lining. Now, as a mature event horse, he is still prone to ulcers in the height of competition season, and anytime he is given phenylbutazone he gets irritable. He colicked last year after a week of bute and has not been given that medication since. As an active athlete, however, he could occasionally benefit from an antiinflammatory medication.
The best option for Jinx is probably firocoxib. Sold under the name Equioxx, firocoxib is a COX-2 inhibitor, meaning it targets only certain classes of cyclooxygenase enzymes---those associated with harmful inflammation ---while typically preserving those that have a protective function. This means that firocoxib can often be given to horses who are sensitive to conventional NSAIDs with much less risk of adverse side effects, particularly right dorsal colitis, a serious condition.
If a horse under my care has a history of bad reactions to NSAIDs that inhibit both COX-1 and COX2, I will try to use firocoxib as an alternative whenever possible. The problem is
that this medication---available in injectable or paste form---can get expensive. For owners who can manage it financially, it’s a great alternative, though.
The standard dose of Equioxx is .1 mg per kilogram of body weight once daily for up to 14 days. I try to not keep horses on it much longer than 10 days. And while there is a much lower risk of side effects, they can occur. That’s because even though almost all the COX-2 prostaglandins we are inhibiting are inflammatory, some have antiinflammatory properties, and an individual’s immune response can vary.
I also instruct the owner that we may have to give a higher dose the first time to get the blood levels to where they need to be. Jinx tolerates it well, and the owner is relieved that we have another medication we can use to help control inflammation, because he is a hardworking horse.