Vet Guide to Bute (Phenylbutazone) in 2025 🐾

Hi, I’m Dr Duncan Houston, BVSc, founder of Ask A Vet. Today we explore phenylbutazone—commonly called “Bute”—an older but potent NSAID that can help dogs with severe musculoskeletal pain or post-op discomfort. We’ll discuss dosing, risks, monitoring, and why this drug must never be given to cats.

📘 What Is Phenylbutazone?

Phenylbutazone is a non-selective NSAID that inhibits COX-1 and COX-2, reducing inflammation and pain, especially in musculoskeletal conditions like arthritis or soft-tissue injury :contentReference[oaicite:3]{index=3}. It's still widely used in horses, but only occasionally in dogs when safer options are inadequate :contentReference[oaicite:4]{index=4}.

✅ When It’s Used in Dogs (Rarely)

• Severe or refractory osteoarthritis
• Postoperative pain in complex orthopedic surgeries
• When first-line NSAIDs (like carprofen, meloxicam) are ineffective or cause side effects :contentReference[oaicite:5]{index=5}
• Always under strict veterinary supervision, with bloodwork and GI protectants

🛑 Not for Cats

Phenylbutazone is contraindicated in cats. Reports detail severe side effects—vomiting, diarrhea, neurological symptoms, bone marrow suppression—even at low doses :contentReference[oaicite:6]{index=6}.

📐 Dog Dosing Guidelines

Use only under veterinary direction:

• Loading dose: 15–22 mg/kg orally every 8–12 hours for 7 days :contentReference[oaicite:7]{index=7}
• Maintenance: 10 mg/kg daily or every 24 hrs, with careful monitoring :contentReference[oaicite:8]{index=8}

Always give with food to protect the stomach:contentReference[oaicite:9]{index=9}.

⏱️ Onset & Duration

Phenylbutazone usually takes effect in ~30–60 minutes, with analgesic action lasting ~12 hours :contentReference[oaicite:10]{index=10}.

⚠️ Side Effects & Risks

Common in dogs:

• GI upset: vomiting, diarrhea, ulcers, bleeding :contentReference[oaicite:11]{index=11}
• Lethargy, reduced appetite

Serious but rare:

• Bone marrow suppression—anemia, low white cells :contentReference[oaicite:12]{index=12}
• Kidney or liver damage—especially with dehydration or long-term use :contentReference[oaicite:13]{index=13}

In overdose:

• Seizures, ataxia, tremors, panting, hyperthermia, organ failure :contentReference[oaicite:14]{index=14}

🔬 Drug Interactions

• Never combine with other NSAIDs, aspirin, or corticosteroids—dangerous for GI and kidneys :contentReference[oaicite:15]{index=15}
• Caution with diuretics, ACE inhibitors, aminoglycosides, warfarin, phenytoin—can increase adverse effects :contentReference[oaicite:16]{index=16}

🩺 Monitoring Your Dog

• Baseline and periodic CBC, kidney, and liver tests for long-term use
• Use GI protectants: omeprazole, cimetidine, or sucralfate :contentReference[oaicite:17]{index=17}
• Watch for appetite, stool changes, thirst, urination, energy

⏳ Missed Dose & Overdose Management

• If a dose is missed, give it as soon as possible and continue normally—do not double the next dose.
• Signs of overdose (vomiting, lethargy, tremors)—seek vet care immediately :contentReference[oaicite:18]{index=18}

🏡 Clinical Example

🐶 Large-breed dog with severe arthritis

• Start Bute 15 mg/kg every 12 hours for 7 days with food + NSAID gastroprotectant
• Re-evaluate: if pain improves, taper to 10 mg/kg daily; if side effects appear, stop and switch
• Repeat bloodwork after 10 days and monitor monthly while on therapy

❓ FAQs

Why not use safer NSAIDs first?

Drugs like carprofen, meloxicam, or grapiprant have better safety profiles and are preferred. Bute is reserved for severe or refractory cases :contentReference[oaicite:19]{index=19}.

Can Bute be used long-term?

Prolonged use is risky. It's best for short-term pain relief, with strict monitoring.

Is Bute safe for pregnant dogs?

Use with caution. While teratogenicity hasn’t been demonstrated in dogs, NSAIDs can affect fetal circulation—only use if needed and under vet guidance :contentReference[oaicite:20]{index=20}.

What about horses?

Horses tolerate Bute better (2.2–4.4 mg/kg/day). But in dogs, the margin of safety is narrower—so extra care is essential.

📌 Final Takeaways

• Bute is a potent NSAID for dogs with severe musculoskeletal pain but is rarely used due to serious risks.
• Dose carefully: loading (15–22 mg/kg q8–12h), then maintenance (≈10 mg/kg q24h)—always with food & GI protectants.
• Monitor bloodwork and watch for GI, kidney, liver, or bone marrow problems.
• Never combine with other NSAIDs or steroids. Do not give to cats.
• Use for short periods only, under strict veterinary oversight.

Curious if Bute might help your dog’s severe pain—or safer alternatives are available? Download the Ask A Vet app for personalized veterinary advice, ongoing monitoring tools, and 24/7 expert support for your dog’s comfort. Your dog deserves the best care! 🐶❤️