By Dr. Michelle Frye, DVM · Published 2026-05-01
TL;DR. Carprofen (Rimadyl, Carprovet, Carprieve, Novox) is an FDA-approved canine NSAID for arthritis and post-surgical pain. Dosed 2.2 mg/kg twice daily or 4.4 mg/kg once daily. Onset within 1–2 hours. For dogs only. Never with steroids or another NSAID. Baseline bloodwork before chronic use; recheck every 6 months.
The Old Lab Who Stopped Greeting You at the Door
You used to come home and there she was, tail thumping the wall, working her way up to a stand. Now she stays on the bed and lifts her head with an apologetic look. She's not depressed. She's not done with you. Her hips hurt. The X-ray will show what your eyes already know — osteoarthritis, the unromantic disease of nearly every senior large-breed dog.
Carprofen is the drug that gives you back the tail thump. Used correctly, it is one of the great quality-of-life interventions in veterinary medicine. Used incorrectly, it is one of the great preventable causes of GI ulceration and kidney injury.
What Carprofen Actually Does
Carprofen is a non-steroidal anti-inflammatory drug (NSAID) that selectively inhibits the COX-2 enzyme driving pain and inflammation, while sparing much of the COX-1 activity that protects the stomach lining and kidneys. It was the first NSAID FDA-approved for long-term canine use (Rimadyl, 1997) and remains the workhorse of canine arthritis management nearly thirty years later.
- Dose: 2.2 mg/kg orally every 12 hours, OR 4.4 mg/kg once daily.
- Onset: 1–2 hours.
- Forms: chewable beef-flavored tablet, caplet, injectable.
- Brand equivalents: Rimadyl, Carprovet, Carprieve, Novox. All identical at the active-ingredient level.
Things People Are Wrong About
Myth 1: "My cat can have a tiny bit." Cats lack the enzyme needed to metabolize carprofen safely. Even one dose can cause kidney injury or GI ulceration. Use Onsior or meloxicam (per cat-specific dosing) instead, prescribed by your veterinarian.
Myth 2: "He can have it with prednisone for the bad days." No. NSAID + steroid is the most preventable cause of GI ulceration in dogs. Pick one. Switch with a 5–7 day washout under veterinary direction.
Myth 3: "It killed Labradors in the 90s." Idiosyncratic hepatic reactions in a small number of Labradors made early headlines. Hundreds of millions of doses later, the safety profile is well characterized: rare in any breed, not a Lab-only phenomenon, and identifiable on routine bloodwork.
Myth 4: "He's been on it for years and he's fine, no need for bloodwork." Annual bloodwork (CBC, chemistry) is the cheapest insurance you'll ever buy. The earliest signs of NSAID-related kidney or liver stress show up in numbers before they show up in symptoms.
When NOT to Use Carprofen
Not for cats. Not with another NSAID. Not with corticosteroids. Use cautiously in dogs with kidney disease, liver disease, dehydration, bleeding disorders, or active GI ulcers. Stop the drug and call your veterinarian if your dog stops eating, vomits repeatedly, develops black or tarry stool, becomes jaundiced, or seems unusually weak.
What I Tell Owners After 30 Years
NSAIDs are how we give old dogs their tail thumps back. They are also how we get into trouble when we mix them with steroids, skip bloodwork, or give them to cats. Use carprofen for what it is: a safe, effective, daily anti-inflammatory for the right dog with appropriate monitoring. Combine it with weight management, controlled exercise, joint supplements, and (for severe cases) referral for adjunct therapies like Adequan injections, laser, or hydrotherapy. Your dog earns those tail thumps; carprofen helps her have them.
Frequently Asked Questions
How long does carprofen take to work?
Initial pain relief is usually visible within 1–2 hours, with full effect in 24–48 hours. For arthritis, the cumulative anti-inflammatory benefit builds over the first 1–2 weeks.
Is Rimadyl the same as carprofen?
Yes. Rimadyl is the original Zoetis brand of carprofen. Carprovet, Carprieve, and Novox are pharmaceutically equivalent generic versions.
Can cats take carprofen?
No. Cats lack the enzyme needed to metabolize carprofen safely. Use feline-labeled NSAIDs (such as Onsior) or meloxicam at cat-specific dosing under veterinary direction.
Can I give carprofen with prednisone?
No. The combination dramatically raises the risk of GI ulceration and kidney injury. A 5–7 day washout is required when switching.
What are the side effects of carprofen?
Most common are mild GI upset, decreased appetite, and soft stool. Serious but rare effects include GI ulceration, kidney injury, and idiosyncratic liver reactions — all detectable on bloodwork before symptoms in most cases.
How long can a dog stay on carprofen?
Dogs can take carprofen long-term for arthritis with appropriate monitoring — baseline bloodwork before starting, then a recheck at 2–4 weeks and every 6 months thereafter.
What should I do if my dog stops eating on carprofen?
Stop the carprofen and call your veterinarian. Loss of appetite is one of the earliest signs of GI complications and should be evaluated promptly.
Where can I buy carprofen for my dog?
Carprofen is prescription-only. Smarty Vets dispenses Rimadyl, Carprovet, Carprieve, and Novox from a licensed pharmacy.
This article is for educational purposes and is not a substitute for veterinary advice. Always consult your veterinarian before starting, stopping, or changing any medication for your pet.