Diclofenac 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.

Diclofenac is a prescription nonsteroidal anti-inflammatory drug (NSAID) used in horses to help control pain and inflammation. In the U.S., the FDA-approved equine product is Surpass®, a 1% diclofenac sodium topical liposomal cream labeled for osteoarthritis in specific joints: the hock, knee, fetlock, and pastern. The liposomal formulation is designed to improve local delivery through the skin over the affected joint.

In equine practice, diclofenac may also be used as an ophthalmic medication in some cases. Topical diclofenac eye drops are not the same product as Surpass cream, and they are used for different problems. Your vet may consider ophthalmic diclofenac as part of an eye treatment plan when inflammation is present and steroid eye medications are not ideal.

Even though diclofenac is applied topically, it is still an NSAID. That means it can carry some of the same risks seen with other anti-inflammatory drugs, especially if too much is used, if it is combined with other NSAIDs or steroids, or if the horse already has stomach, kidney, liver, or hydration concerns. This is why your vet should guide both the product choice and the treatment plan.

The main labeled use of diclofenac in horses is the control of pain and inflammation associated with osteoarthritis in the hock, knee, fetlock, and pastern joints. It is often considered when a horse has localized joint soreness, stiffness, or mild lameness and your vet wants a topical NSAID option rather than, or sometimes before, relying on a systemic anti-inflammatory.

In real-world care, your vet may use diclofenac as one part of a broader arthritis plan that can also include exercise changes, farriery adjustments, weight management, joint support, or other medications. It is not a cure for osteoarthritis, but it may help improve comfort and day-to-day function.

For the eye, veterinary ophthalmologists may use diclofenac 0.1% ophthalmic solution as a topical anti-inflammatory for conditions such as uveitis or other inflammatory eye disorders. In horses with active uveitis, AAEP educational material notes that topical diclofenac may be used 3 to 4 times daily, especially in severe cases or when corticosteroids are contraindicated because of a corneal ulcer or calcific band keratopathy. Eye disease can worsen quickly, so any squinting, tearing, cloudiness, or light sensitivity should prompt a same-day call to your vet.

For Surpass® topical cream, the labeled equine dose is one 5-inch ribbon of cream, which contains about 73 mg of diclofenac, applied twice daily over the affected joint for up to 10 days. The cream should be rubbed thoroughly into the hair covering the joint until it disappears, and gloves should be worn during application. Your vet may also limit how many joints are treated and for how long, because higher total exposure can increase the risk of side effects.

Do not change the amount, frequency, or duration on your own. Using more than directed, treating multiple joints without veterinary guidance, or extending treatment longer than planned can increase systemic absorption. The product label specifically warns that excessive doses applied to the skin can enter the bloodstream and raise the risk of adverse effects.

For ophthalmic diclofenac, dosing depends entirely on the eye condition being treated. In horses with severe uveitis, AAEP educational guidance notes diclofenac 0.1% may be used 3 to 4 times daily, but eye medications are highly case-specific. If your horse has a corneal ulcer, fungal infection risk, or multiple eye medications, your vet may adjust the schedule carefully. Never substitute joint cream for eye medication, and never use human diclofenac products in your horse unless your vet specifically instructs you to do so.

With topical diclofenac cream, many horses do well when the medication is used exactly as directed. Still, because diclofenac is an NSAID, side effects can happen. The equine client information sheet advises pet parents to watch for weight loss, colic, diarrhea, or icterus (yellowing of the gums, skin, or whites of the eyes). In the field study for Surpass, one diclofenac-treated horse developed colic. In safety testing at much higher-than-labeled doses, gastric ulceration, diarrhea, and weight loss were reported.

More broadly, Merck notes that NSAID toxicosis in horses can cause loss of appetite, soft manure or diarrhea, colic signs, ventral edema, gastric ulceration, and kidney-related complications, especially when dose or duration is excessive. Horses that are dehydrated or that already have kidney, liver, cardiovascular, or gastrointestinal disease may be at higher risk.

If diclofenac is being used in the eye, possible local side effects can include stinging, redness, irritation, swelling, light sensitivity, or bleeding in the eye. Eye discomfort that worsens instead of improving is always a reason to contact your vet promptly.

Stop the medication and call your vet right away if your horse develops decreased appetite, worsening colic signs, diarrhea, depression, jaundice, or any unusual reaction after starting diclofenac. See your vet immediately for severe eye pain, marked squinting, a cloudy cornea, or sudden vision changes.

The most important interaction concern with diclofenac in horses is combining it with other anti-inflammatory drugs. The Surpass client information sheet says it should not be given with other NSAIDs such as aspirin, phenylbutazone, or flunixin, and it also should not be combined with corticosteroids such as dexamethasone, prednisone, cortisone, or triamcinolone unless your vet specifically directs otherwise. Using these together can raise the risk of ulcers, colitis, kidney injury, and other NSAID-related complications.

Your vet should also know if your horse is on diuretics, has a history of ulcers, or has kidney, liver, or cardiovascular disease, because these factors can change how safely an NSAID can be used. Even though diclofenac cream is topical, the label notes that excessive skin dosing can lead to measurable bloodstream exposure.

For ophthalmic diclofenac, VCA notes that no specific drug interactions are well established, but caution is advised in animals with corneal ulceration, bleeding disorders, or when the patient is also receiving systemic NSAIDs or steroids. In practice, eye cases often involve several medications at once, so spacing drops correctly and following your vet's schedule matters.

Tell your vet about every medication, supplement, joint product, and topical treatment your horse is receiving. That includes over-the-counter products, liniments, and any human medications kept in the barn.