Firocoxib for Horses: Uses, Dosing & Side Effects

This information is for educational purposes only. Never give your pet any medication without your veterinarian's guidance. Dosing, frequency, and safety depend on your pet's specific health profile.

Firocoxib is a prescription nonsteroidal anti-inflammatory drug (NSAID) used in horses to reduce pain and inflammation. It belongs to the COX-2 selective NSAID group, often called a coxib. In horses, the labeled oral products are used for the control of pain and inflammation associated with osteoarthritis, and they are available by prescription because your vet needs to decide whether this medication is appropriate and monitor for side effects.

Compared with older NSAIDs, firocoxib is designed to target inflammation more selectively. That can be helpful for some horses needing pain control, especially when your vet is trying to balance comfort with gastrointestinal and kidney safety. Even so, it is still an NSAID, so it can still cause serious problems in some horses, including mouth ulcers, digestive injury, and kidney complications.

Brand names used in horses include Equioxx and approved generic horse products such as EquiCoxib. Oral horse products are dosed specifically for equine use. Your vet may choose paste, oral solution, tablets, or in some cases injectable firocoxib followed by oral treatment, depending on the horse's condition, handling needs, and treatment plan.

The main labeled use of firocoxib in horses is control of pain and inflammation associated with osteoarthritis. That includes horses with chronic joint soreness, stiffness after rest, reduced willingness to work, or lameness linked to degenerative joint disease. Improvement can sometimes be noticed within hours to a couple of days, but the full response varies from horse to horse.

Your vet may also use firocoxib as part of a broader pain-management plan for other painful inflammatory conditions when they feel it is a good fit. In real-world equine practice, NSAIDs are often chosen for lameness, soft tissue injury, and post-procedure discomfort, but the exact choice depends on the horse's age, hydration status, ulcer history, kidney and liver health, competition rules, and what other medications are being used.

Firocoxib is not the only option. Some horses do better with another NSAID, while others need a multimodal plan that may include rest, rehabilitation, corrective farriery, joint therapies, ulcer protection, or imaging. The best choice is the one that matches your horse's diagnosis, risk factors, and your goals with your vet.

For labeled equine oral products, the usual dose is 0.045 mg/lb (0.1 mg/kg) by mouth once daily for up to 14 days. FDA-approved horse tablets contain 57 mg each and are intended to be dosed by body weight. A 57 mg tablet corresponds to about a 500 lb horse, which works out to roughly 0.114 mg/lb or 0.25 mg/kg if a full tablet were given to a 500 lb horse, so your vet may use tablet splitting or a different formulation to improve accuracy in smaller horses and ponies. Oral paste syringes are calibrated by weight and are often easier for precise equine dosing.

Do not change the dose, frequency, or treatment length on your own. Firocoxib has a relatively long half-life in horses, so giving extra doses or combining it with another NSAID can raise the risk of toxicity. If you miss a dose, contact your vet for guidance. In many cases, they will advise giving the next scheduled dose rather than doubling up, but the safest plan depends on timing and your horse's health history.

Tell your vet before starting firocoxib if your horse has had kidney disease, liver disease, gastrointestinal ulcers, dehydration, poor appetite, diarrhea, or prior NSAID reactions. Safety has not been established in horses under 1 year of age or in breeding horses, pregnant mares, or lactating mares. Horses intended for human food use should not receive labeled firocoxib products.

Many horses tolerate firocoxib well when it is used exactly as prescribed, but side effects can still happen. The most recognized problems in horses involve the mouth and face, including sores or ulcers on the tongue or inside the mouth, scabs or redness around the lips, and discomfort while chewing. You may also notice reduced appetite, less interest in water, or a change in attitude.

Like other NSAIDs, firocoxib can also affect the digestive tract and kidneys. Warning signs include colic signs, soft manure or diarrhea, weight loss, ventral edema, changes in drinking or urination, jaundice, lethargy, or worsening depression. In horses, NSAID injury can involve the stomach or the right dorsal colon, and some horses are unusually sensitive, meaning toxicity can occur even near recommended doses.

See your vet immediately if your horse develops mouth ulcers, stops eating, has diarrhea, shows colic signs, seems dehydrated, urinates less, or becomes dull while taking firocoxib. Stop the medication unless your vet tells you otherwise. Early recognition matters because many NSAID reactions improve when the drug is stopped promptly and supportive care begins quickly.

The most important interaction is with other NSAIDs or corticosteroids. Firocoxib should not be given at the same time as medications such as phenylbutazone, flunixin meglumine, ketoprofen, diclofenac, aspirin, dexamethasone, prednisolone, or triamcinolone, unless your vet has created a specific plan with an appropriate washout period. Combining these drugs can sharply increase the risk of ulcers, right dorsal colitis, kidney injury, and other serious complications.

Extra caution is also needed with medications or situations that can stress the kidneys, such as dehydration, some diuretics, and other potentially nephrotoxic drugs. Because many drugs are protein-bound, your vet may review the full medication list before prescribing firocoxib, especially if your horse is receiving multiple therapies, supplements, or recent injectable treatments.

Tell your vet about every medication and supplement your horse receives, including over-the-counter products, ulcer medications, joint supplements, and any recent injections. If your horse needs to switch from one NSAID to another, ask your vet about the safest timing rather than making the change yourself.