💊 NSAID · COX-1/COX-2 Inhibitor
Carprofen Dosage Calculator for Dogs
Precise carprofen (Rimadyl, Novox, Vetprofen) dosing for dogs by weight, dosing frequency, and indication — covering osteoarthritis, post-surgical pain, and acute musculoskeletal conditions with tablet selection and hepatotoxicity monitoring guidance.
Prescription NSAID — veterinary supervision required. Never combine with other NSAIDs, aspirin, or corticosteroids. Obtain baseline bloodwork (ALT, ALP, BUN, creatinine) before starting; recheck every 3–6 months on long-term therapy. Discontinue immediately if vomiting, black stools, jaundice, or lethargy occur.
What Is Carprofen?
Carprofen (Rimadyl, Novox, Vetprofen, Canidryl) is a propionic acid-class NSAID that inhibits both cyclooxygenase-1 (COX-1) and COX-2 enzymes, reducing prostaglandin synthesis and thereby decreasing inflammation, pain, and fever. While it has some preferential COX-2 selectivity compared to aspirin, it is not a pure COX-2 inhibitor like deracoxib. It was the first NSAID specifically approved by the FDA for long-term use in dogs (1997).
Carprofen is available as 25 mg, 75 mg, and 100 mg chewable (beef-flavoured) tablets, making dose titration convenient across the full weight range from small breeds to giant breeds. It achieves peak plasma concentrations within 1–3 hours of oral administration.
Clinical Pharmacology
- Mechanism: COX-1/COX-2 inhibition → ↓ prostaglandin E2, thromboxane A2, prostacyclin
- Oral bioavailability: ~90% — excellent; give with or without food
- Half-life (dogs): ~8 hours; once or twice daily dosing both effective
- Protein binding: ~99% — high; drug interactions with other protein-bound drugs possible
- Metabolism: Extensive hepatic glucuronidation and oxidation (CYP2C); dose-reduce in hepatic disease
- Elimination: ~70% faecal (bile-excreted), ~30% renal
FDA-Approved Indications
- Osteoarthritis (OA): Long-term management of pain and inflammation
- Post-operative analgesia: Soft tissue and orthopaedic surgery pain
- Acute musculoskeletal pain: Sprains, strains, intervertebral disc disease (IVDD)
Available Formulations
- Chewable tablets: 25 mg, 75 mg, 100 mg (beef-flavoured)
- Caplets: 25 mg, 75 mg, 100 mg
- Injectable solution: 50 mg/mL (for intra/peri-operative use by vet clinic)
How to Use This Calculator
- Enter your dog’s current body weight in kg or lbs — use lean body weight if obese
- Select the dosing regimen: once daily (4.4 mg/kg q24h) or twice daily (2.2 mg/kg q12h) — both are FDA-approved; once-daily simplifies compliance
- Choose the tablet strength available (25, 75, or 100 mg)
- Select the indication — post-surgical use may differ from chronic OA management
- Click Calculate for dose, tablet count per administration, and safety reminders
🧮 Carprofen Dose Calculator
Carprofen Dosing Result
Weight-Based Quick Reference
| Weight | q24h dose (4.4 mg/kg) | q12h dose (2.2 mg/kg) | Best tablet |
|---|---|---|---|
| 5 kg (11 lbs) | 22 mg/day | 11 mg × 2 | 25 mg (½ tablet × 2) |
| 10 kg (22 lbs) | 44 mg/day | 22 mg × 2 | 25 mg × 2 once daily |
| 20 kg (44 lbs) | 88 mg/day | 44 mg × 2 | 75 mg + 25 mg once daily |
| 30 kg (66 lbs) | 132 mg/day | 66 mg × 2 | 100 mg + 25 mg once daily |
| 40 kg (88 lbs) | 176 mg/day | 88 mg × 2 | 100 mg + 75 mg once daily |
| 50 kg (110 lbs) | 220 mg/day | 110 mg × 2 | 100 mg × 2 + 25 mg once daily |
Safety Monitoring Protocol
| Timepoint | Tests | Action if Abnormal |
|---|---|---|
| Before starting | ALT, ALP, BUN, creatinine, urinalysis | Do not start if significantly elevated; investigate |
| 2–4 weeks after start | ALT, ALP | Discontinue if >3× ULN; assess for hepatotoxicity |
| Every 3–6 months | Full biochemistry, urinalysis | Dose reduce or discontinue if hepatic/renal changes |
| Any time — warning signs | Vomiting, diarrhoea, black stools, jaundice, lethargy, polyuria/polydipsia | Discontinue immediately; emergency vet visit |
Frequently Asked Questions
Yes — carprofen is FDA-approved for long-term daily use in dogs and is one of the most prescribed chronic pain medications in veterinary medicine. However, long-term use requires regular blood monitoring (ALT, ALP, BUN, creatinine) every 3–6 months to detect hepatotoxicity or renal impairment early. Studies have shown carprofen is well-tolerated long-term in the vast majority of dogs, but individual susceptibility varies, especially in Labrador Retrievers who may be at higher risk of idiosyncratic hepatotoxicity.
Both once-daily (4.4 mg/kg q24h) and twice-daily (2.2 mg/kg q12h) regimens deliver the same total daily dose and are FDA-approved. Once-daily dosing is more convenient and improves owner compliance. Twice-daily dosing distributes the GI load into two smaller doses, which may reduce gastric irritation in sensitive dogs. Clinical efficacy is considered equivalent. Most veterinarians now recommend once-daily dosing for long-term OA management unless the dog has GI sensitivity.
Yes — combining carprofen with gabapentin or tramadol is a common and safe multimodal pain management approach used extensively in veterinary medicine. These drugs work through different mechanisms (carprofen = anti-inflammatory; gabapentin = calcium channel modulator for neuropathic pain; tramadol = opioid/monoamine reuptake). There are no significant pharmacokinetic interactions. This combination is particularly useful for severe OA, disc disease, or cancer pain where a single drug is insufficient.
A washout period of at least 5–7 days (preferably 14 days) is recommended when switching between NSAIDs to reduce the risk of additive GI ulceration and renal toxicity. Never give two NSAIDs simultaneously. If switching from carprofen to meloxicam or vice versa, discontinue carprofen, wait the full washout period, then begin the new NSAID at the lowest effective dose. The washout period also applies when transitioning to or from corticosteroids (e.g., prednisolone).
Yes — Labrador Retrievers appear to have a breed-specific predisposition to idiosyncratic hepatotoxicity from carprofen compared to other breeds. The mechanism is not fully understood but appears immune-mediated rather than dose-dependent. This does not mean carprofen should be avoided in Labradors — it is still widely and safely used in this breed — but closer liver monitoring (every 3 months rather than 6 months) is advisable. Other breeds reported with increased hepatic sensitivity include Dobermann Pinschers and Irish Wolfhounds.
Carprofen is not recommended for puppies under 6 weeks of age. For puppies older than 6 weeks, it can be used for post-surgical pain under veterinary supervision. Long-term use in young growing dogs should be approached cautiously as prolonged NSAID use may theoretically affect bone and cartilage development. For chronic joint conditions in growing dogs (e.g., hip dysplasia), the risk-benefit ratio should be discussed with a veterinary orthopaedic specialist.
References
- Plumb DC. Plumb’s Veterinary Drug Handbook, 9th ed. Wiley-Blackwell; 2018.
- Rimadyl (carprofen) Prescribing Information. Zoetis Inc.; 2023.
- KuKanich B, et al. The effects of inhibiting cytochrome P450 3A, p-glycoprotein, and gastric acid secretion on the oral pharmacokinetics of methadone in dogs. J Vet Pharmacol Ther. 2008;31(2):142-149.
- Papich MG. Saunders Handbook of Veterinary Drugs, 4th ed. Elsevier; 2016.
- Johnston SA, Budsberg SC. Nonsteroidal anti-inflammatory drugs and corticosteroids for the management of canine osteoarthritis. Vet Clin North Am Small Anim Pract. 1997;27(4):841-862.
- MacPhail CM, et al. Hepatocellular toxicosis associated with administration of carprofen in 21 dogs. J Am Vet Med Assoc. 1998;212(12):1895-1901.