🚫 Why Previcox Isn’t Legal for Horses 🐴 – 2025 Veterinary Advice

By Dr Duncan Houston BVSc

There’s a common misconception in the equine world that the canine NSAID Previcox® can be used interchangeably with the horse-labeled version Equioxx® to save money. ❌ Unfortunately, under FDA regulations, this is not only discouraged—it’s illegal.

💊 What Are Previcox® and Equioxx®?

Both drugs contain the same active ingredient: firocoxib, a COX-2 selective non-steroidal anti-inflammatory (NSAID) used for pain relief and inflammation—especially in arthritis. However, each is formulated, tested, and approved for a specific species:

• Previcox® – FDA approved for dogs
• Equioxx® – FDA approved for horses

⚠️ Why It’s Illegal to Use Previcox in Horses

The FDA requires species-specific approval for veterinary drugs. That means you can’t legally use a dog-labeled drug in a horse just because it’s cheaper.

Testing for FDA approval involves evaluating safety, absorption, excretion, metabolism, and efficacy—all of which differ by species. This testing is expensive, especially in horses 🐎, where maintaining herds for trials adds further cost.

In contrast, human drugs may be used in animals if no veterinary-approved equivalent exists or if cost is a concern, but this flexibility does not extend between animal species.

📜 The Legal Exception: Extra-Label Drug Use

The Animal Medicinal Drug Use Clarification Act (AMDUCA) allows veterinarians to prescribe drugs off-label, but only:

• If there’s no approved alternative available
• When done under a valid veterinary-client-patient relationship
• And not for economic convenience

Using Previcox in a horse solely because it's cheaper does not qualify and violates federal law. Your veterinarian’s license could even be at risk if they knowingly approve such use.

💸 Why Owners Try to Use Previcox Anyway

It comes down to cost. Equioxx is more expensive than Previcox, even though the active ingredient is identical. But remember: what’s saving a few dollars could mean violating drug law and risking the safety of your horse.

✅ Always Choose Equioxx for Horses

Equioxx is tested and proven safe for horses, with proper dosing formulations and safety data. It is the only legal choice for equine pain and inflammation management with firocoxib.

📲 Have Questions?

Download the Ask A Vet app from AskAVet.com for expert help choosing the right medications for your horse. Our licensed vets are just a tap away 🐴💬.

Legal compliance ensures not only your horse’s safety but also supports veterinary standards we can all trust. Let’s keep your animals safe, happy, and pain-free—the right way.

— Dr Duncan Houston BVSc