🐾 Guide to Robenacoxib (Onsior) for Dogs & Cats in 2025 💊

By Dr Duncan Houston

Robenacoxib—marketed as Onsior—is a veterinary NSAID in the COX‑2 selective “coxib” class, approved for short-term pain relief after surgery in both cats and dogs. First released for cats, its canine approval followed, earning trust in post-op pain control and easing arthritis discomfort. Let's dive into how it works, when it's used, and crucial precautions for your pet’s safety. 🐶🐱

🧬 Background: What Makes Robenacoxib Special

Traditional NSAIDs block both COX‑1 and COX‑2 enzymes. COX‑1 safeguards the stomach lining, kidneys, and platelet function, while COX‑2 drives inflammation and pain. Robenacoxib selectively inhibits COX‑2, sparing COX‑1, which translates to reduced GI and kidney side effects compared to non-selective NSAIDs. Additionally, it concentrates at inflamed tissue, leaving healthy organs relatively untouched.

💡 Key Uses

• Post-operative pain control for up to 3 days following surgery (one dose on day of surgery counts as Day 1).
• Short- to long-term management of osteoarthritis in both cats and dogs—used off‑label beyond 3 days with vet monitoring.

🌍 International Usage

Approved duration:

📦 Formulations Available

• 🐱 Cats: 6 mg tablets
• 🐶 Dogs: 10 mg, 20 mg, 40 mg tablets

Tablets should be stored at room temperature, shielded from light, and never crushed.

⚠️ Common Side Effects

• 💩 Gastrointestinal upset (vomiting, soft stools), usually minor and reduced when given with food

❗ Serious Adverse Effects

• 🩸 GI ulceration and bleeding
• 💧 Kidney dysfunction—especially in dehydrated or kidney-compromised pets
• 🧠 Liver impairment or toxicity with elevated liver enzymes

Large or prolonged doses—especially during long-term use—make monitoring essential. Notify your vet immediately of decreased appetite, vomiting, diarrhea, lethargy, or jaundice.

🔗 Drug Interactions

• ❌ No combo with other NSAIDs or corticosteroids — increased risks of bleeding, ulcers, and organ damage
• ⚠️ ACE inhibitors may become less effective due to NSAID interference with kidney blood flow
• ⚠️ Fluconazole can raise robenacoxib blood levels—monitor closely
• ⚠️ Methotrexate toxicity risk increased with concurrent use
• ❗ Avoid in dehydrated pets or those on diuretics
• ⚠️ Interference with other protein-bound drugs possible—monitor for toxicity

✅ Usage Tips & Storage

• 🕒 Administer once daily, per vet instruction
• 🍽️ Give with or without food—food can reduce GI upset
• ❌ If a dose is missed, don’t double up—give the next scheduled dose
• 🛡️ Store tablets at room temperature out of light—do not refrigerate or crush

🩺 Monitoring & Precautions

• Check kidney/liver function before and during long-term use
• Ensure hydration—especially during illness or heat
• Stop use and vet consult if signs of GI upset, kidney/liver issues arise
• Not tested in pregnant/nursing pets—avoid in these populations

📈 Long-Term Off‑Label Use for Osteoarthritis

While typically approved for 3 days, veterinarians may prescribe Onsior for extended management of chronic arthritic pain AND regularly monitor blood work—liver enzymes, kidney values—to minimize long-term risk.

🔄 Off‑Label & Extended Use Safety Measures

• 🧪 Pre-treatment labs: CBC, creatinine/BUN, ALT/ALKP
• 🗓️ Recheck labs after 7–14 days, then every few months for chronic use
• 🩻 Observe for appetite loss, vomiting, lethargy, jaundice

🔥 GI & Kidney Risk Warning

NSAIDs reduce prostaglandins that maintain stomach/kidney blood flow. So any pet with dehydration, GI issues, or kidney compromise must only receive NSAIDs like Onsior under strict veterinary oversight. 🩹

🐕🐈 When Not to Use Robenacoxib

• Pre-existing GI ulcers
• Kidney or liver disease
• Dehydration
• Concurrent NSAID or steroid use
• Pregnant or nursing animals

🏥 Veterinary Oversight is Key

Robenacoxib is potent and effective—but only when used responsibly. The safest approach is strict veterinary guidance and monitoring.

🛍️ Shopify-Friendly Note

Onsior tablets are prescription-only. If you're a veterinary clinic using Shopify, ensure clear disclaimers, dosage guidance, and monitoring advice accompany all product listings. Offer reminder services for lab follow-up if selling long-term supply packs.

✔️ Summary Table

🎯 Final Advice from Dr Duncan Houston

Robenacoxib (Onsior) is a powerful tool for managing acute pain in dogs and cats—especially post-operatively. Its COX‑2 selectivity offers a safer alternative to traditional NSAIDs, but the risk to the GI tract, kidneys, and liver remains. Long-term use demands careful monitoring, hydration, and attention to side effects. Always consult your vet, follow dosing directions, and report any signs of ill health promptly. With proper use, Onsior can help your pet recover comfortably and safely in 2025 and beyond. 🐾❤️