Phenylbutazone
Also known as: Butazolidin, Bute, Phenylbute
**For Horse Owners:** * "Bute" is highly effective for managing bone and joint pain. Always administer exactly as prescribed by your veterinarian. * > **CRITICAL WARNING:** Never administer the liquid injectable form into the muscle (IM) or under the skin (SC). It must be given strictly into the vein (IV) by a professional. Incorrect injection causes severe tissue damage and sloughing. * Watch closely for signs of stomach ulcers or kidney issues: loss of appetite, diarrhea, signs of colic, or swelling in the legs/belly. Stop the medication and contact your vet if these occur. **For Dog Owners:** * This medication is rarely used in dogs today due to the availability of safer alternatives. If prescribed, monitor your dog very closely for vomiting, dark/tarry stools, or lethargy, and contact your vet immediately if these occur. **Food Animal Restrictions:** * Strictly banned by the FDA for use in female dairy cattle 20 months of age or older. * If used extralabel in beef cattle, strict meat withdrawal times apply (e.g., 1 dose = 30 days, 2 doses = 35 days). Consult your veterinarian.
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
What it is used for
- General inflammation/pain
- General inflammation/pain
- To reduce pain or pyrexia associated with pleuropneumonia
- General musculoskeletal inflammation
- Adjunctive treatment of colic (to reduce endotoxic effects)
- Adjunctive treatment of laminitis
- Osteoarthritis
- General inflammation/pain
- General inflammation/pain
- General inflammation/pain
- General inflammation/pain
- Analgesia
How it is given
Possible side effects
- Gastrointestinal and oral erosions/ulcers
- Hypoalbuminemia (especially in foals/ponies)
- Renal papillary necrosis and azotemia
- Sodium and water retention (edema)
- Blood dyscrasias (agranulocytosis, aplastic anemia)
- Hepatotoxicity
- Severe tissue necrosis and sloughing (if injected IM or SC)
- CNS stimulation and seizures (if injected intracarotid)
- Gastrointestinal ulceration and bleeding
- Bone marrow suppression (aplastic anemia, leukopenia)
- Renal papillary necrosis
- Sodium and water retention
Cautions & contraindications
- Known hypersensitivity to phenylbutazone or other NSAIDs
- History of or preexisting hematologic or bone marrow abnormalities
- Preexisting gastrointestinal ulcers
- Food-producing animals (especially female dairy cattle 20 months of age or older)
- Lactating dairy cattle
- Pre-existing gastrointestinal ulceration
- Renal impairment
- Hepatic impairment
- Hematological disorders
- Use in food-producing animals (banned in many jurisdictions)
- Use with extreme caution in foals and ponies due to increased incidence of hypoproteinemia and GI ulceration. Avoid in horses with known or suspected Equine Gastric Ulcer Syndrome (EGUS). Use cautiously in animals with preexisting renal disease or congestive heart failure (CHF) due to potential for sodium/water retention and decreased renal blood flow. May mask clinical signs of lameness in horses. **WARNING:** Do not administer injectable preparations IM or SC as it is highly irritating and causes necrosis/sloughing. Intracarotid injections may cause CNS stimulation and seizures.
Drug interactions
- Furosemide: Phenylbutazone may antagonize the increased renal blood flow effects caused by furosemide.
- Hepatotoxic Drugs: Concurrent administration may increase the chances of hepatotoxicity developing.
- NSAIDs: Concurrent use increases the potential for adverse GI and renal reactions. (Note: 'Stacking' with ketoprofen shows synergistic toxicity).
- Penicillamine: May increase the risk of hematologic and/or renal adverse reactions.
- Penicillin G: Phenylbutazone may increase the plasma half-life of penicillin G.
- Sulfonamides: Phenylbutazone could potentially displace sulfonamides from plasma proteins, increasing the risk for adverse effects.
- Warfarin: Phenylbutazone could potentially displace warfarin from plasma proteins, increasing the risk for bleeding.
- Corticosteroids: Increased risk of gastrointestinal ulceration
- Other NSAIDs: Increased risk of gastrointestinal ulceration and renal toxicity
- Highly protein-bound drugs (e.g., warfarin): Displacement from plasma proteins leading to increased free drug concentrations
Frequently asked questions
What is Phenylbutazone used for in pets?
**For Horse Owners:** * "Bute" is highly effective for managing bone and joint pain. Always administer exactly as prescribed by your veterinarian. * > **CRITICAL WARNING:** Never administer the liquid injectable form into the muscle (IM) or under the skin (SC). It must be given strictly into the vein (IV) by a professional. Incorrect injection causes severe tissue damage and sloughing. * Watch closely for signs of stomach ulcers or kidney issues: loss of appetite, diarrhea, signs of colic, or swelling in the legs/belly. Stop the medication and contact your vet if these occur. **For Dog Owners:** * This medication is rarely used in dogs today due to the availability of safer alternatives. If prescribed, monitor your dog very closely for vomiting, dark/tarry stools, or lethargy, and contact your vet immediately if these occur. **Food Animal Restrictions:** * Strictly banned by the FDA for use in female dairy cattle 20 months of age or older. * If used extralabel in beef cattle, strict meat withdrawal times apply (e.g., 1 dose = 30 days, 2 doses = 35 days). Consult your veterinarian.
Is Phenylbutazone safe for my pet?
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
This article is for general education and is not a substitute for professional veterinary advice. If your pet is unwell, please consult a veterinarian.
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