The FDA-approved label for Equioxx tablets says they can be given once daily for up to 14 days. That’s the official limit printed on the packaging. In practice, though, many veterinarians prescribe Equioxx well beyond 14 days for horses with chronic conditions like osteoarthritis, and recent research suggests this can be done with a reasonable safety profile when properly monitored.
What the Label Says vs. What Happens in Practice
Equioxx tablets contain 57 mg of firocoxib, a COX-2 selective anti-inflammatory. The labeled dose is one tablet per day for horses weighing 800 to 1,300 pounds, for up to 14 days. That 14-day window reflects the duration of the clinical trials the manufacturer submitted to the FDA for approval. It doesn’t necessarily mean the drug becomes dangerous on day 15.
Because the FDA label caps use at 14 days, any longer course is considered “off-label.” Veterinarians can legally prescribe off-label when they believe the benefit outweighs the risk, and many do so routinely for horses dealing with chronic joint pain. The key difference is that extended use requires closer veterinary oversight, including periodic bloodwork and clinical exams.
What Long-Term Research Shows
A study published in the Journal of Veterinary Internal Medicine tracked horses receiving firocoxib for up to 52 months, well over four years. At a dose of roughly 0.1 mg/kg once daily (slightly below the standard label dose), the researchers found minimal changes in blood chemistry and cell counts. Kidney markers like BUN and creatinine showed no difference between horses on the drug and those that were not. Total protein levels also stayed stable, which is notable because other NSAIDs in horses are linked to a gut condition called right dorsal colitis that typically drives protein levels down.
These results are reassuring, but they come with an important caveat: the horses in the study were monitored regularly, and the dose used was on the lower end. Horses kept at the full label dose for months without any bloodwork are in a different, riskier situation.
Risks of Extended Use
Firocoxib is gentler on the stomach than older NSAIDs like phenylbutazone because it selectively targets inflammatory enzymes while mostly sparing the ones that protect the gut lining. “Mostly” is the operative word. Over long periods, gastrointestinal ulceration and right dorsal colitis remain possible, especially at higher doses or in dehydrated horses.
Kidney stress is the other concern. Any NSAID can reduce blood flow to the kidneys, and horses that are dehydrated, under heavy exercise, or receiving other potentially kidney-taxing medications face higher risk. The long-term study found no measurable kidney damage at the lower maintenance dose, but individual horses vary. Older horses or those with pre-existing kidney issues need more frequent monitoring.
How Vets Monitor Horses on Long-Term Equioxx
Experts recommend weekly measurement of serum albumin or total protein levels for horses on any NSAID. These values drop early when the gut lining is being damaged, often before clinical signs like poor appetite or diarrhea appear. Serum creatinine is the go-to marker for kidney function and should also be checked regularly. Your vet may space out bloodwork to every few weeks once a horse has been stable for a while, but early in a long-term course, weekly checks catch problems before they become serious.
If bloodwork shows dropping protein levels or rising creatinine, your vet will likely reduce the dose or stop the drug and allow a washout period before reassessing.
Finding the Lowest Effective Dose
When horses need Equioxx for months rather than days, most vets try to find the smallest dose that still controls pain. Research using force-plate analysis (essentially a high-tech way to measure how evenly a horse loads its legs) found that a dose of 0.1 mg/kg was enough to measurably reduce chronic lameness. That’s below the standard label dose, which works out to roughly 0.1 to 0.13 mg/kg depending on the horse’s weight.
The half-scored tablet makes it easy to split a 57 mg tablet in two. For a 1,000-pound horse, half a tablet daily is a common long-term maintenance strategy. Some horses do well on every-other-day dosing once their pain is well controlled. Improvement in lameness can appear as early as two days at the standard dose, and within hours at higher loading doses, so there’s usually a quick feedback loop when adjusting.
Medications to Avoid While on Equioxx
Equioxx should never be combined with other NSAIDs. That includes phenylbutazone (“bute”), flunixin (Banamine), ketoprofen, aspirin, and topical diclofenac. Stacking two NSAIDs dramatically increases the risk of gut ulceration and kidney damage. Systemic corticosteroids like dexamethasone, prednisone, and triamcinolone also need to be avoided during Equioxx use.
If you’re switching your horse from one NSAID to another, an appropriate washout period is necessary. The length depends on the specific drugs involved, but your vet will advise on timing. Any medication that can stress the kidneys should be used cautiously or avoided altogether while your horse is on firocoxib.
The Bottom Line on Duration
The label says 14 days. Real-world veterinary practice regularly extends that to months or even years for horses with chronic pain, particularly osteoarthritis. The best available evidence shows this can be done safely at lower maintenance doses with regular blood monitoring. The horses at greatest risk are those left on the full dose indefinitely without any lab work, those that are dehydrated or under-fed, and those accidentally receiving a second NSAID or corticosteroid at the same time. How long your horse can stay on Equioxx is ultimately a decision between you and your vet, guided by bloodwork and your horse’s clinical response.