The safe dosage of phenylbutazone ("bute") for a 500kg horse is 2-4 grams per day.

Phenylbutazone (bute) is a non-steroidal anti-inflammatory (NSAID) commonly used for pain and inflammation in horses. For a 500kg horse, the standard daily dose is 2-4g orally, split into two doses. Never exceed 4g/day without veterinary guidance, as overdosing risks ulcers, kidney damage, or colic.

Dosage Guidelines by Condition

  • Mild pain/inflammation: 2g/day (1g every 12 hours).
  • Moderate pain (e.g., laminitis, arthritis): 3-4g/day (1.5-2g every 12 hours).
  • Short-term use only: Limit to 5 consecutive days unless directed otherwise.
  • Loading dose (rare): Up to 8g on Day 1 (vet-supervised), then reduce.

Administration Methods Compared

Method Dosage Accuracy Ease of Use Cost Notes
Oral paste/syringe ⭐⭐⭐⭐⭐ ⭐⭐⭐⭐ $$ Pre-measured; best for precise dosing.
Powder (top-dressed) ⭐⭐⭐ ⭐⭐ $ Risk of uneven intake if horse refuses feed.
Injectable (IV/IM) ⭐⭐⭐⭐⭐ ⭐ $$$ Vet-administered only; faster onset.

Critical Safety Warnings

  • Never exceed 4g/day for a 500kg horse without veterinary approval.
  • Side effects: Ulcers, diarrhea, kidney/liver toxicity, or behavioral changes.
  • Avoid in: Dehydrated, pregnant, or horses with GI/kidney issues.
  • Drug interactions: Do not mix with other NSAIDs (e.g., flunixin).
  • Withdrawal time: 5-7 days before competition (check regulations).

Signs of Overdose

  1. Severe colic or diarrhea (bloody stools possible).
  2. Lethargy or depression.
  3. Increased thirst/urination or reduced urine output.
  4. Swollen legs or mouth ulcers.
  5. Seizures (rare but emergency).

Alternatives to Bute

  • Flunixin meglumine (Banamine): Better for colic; shorter half-life.
  • Firocoxib (Equioxx): COX-2 selective; gentler on stomach.
  • Acetaminophen (paracetamol): Mild pain (vet-approved dose only).
  • Natural options: Devil's claw, turmeric (supportive, not replacements).