Equine · Equus caballus · typical adult weight 350.00–700.00 kg
Phenylbutazone is dosed at 4.4 mg/kg IV q12h in horses, per Coleman MC. Laminitis. In: Smith BP, Van Metre DC, Pusterla N, eds. Large Animal Internal Medicine. 6th ed. St. Louis, MO: Elsevier; 2020:1235-1238. — Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.1042 (2026-08-01). — Plumb's 10th ed (held) printed p.1013, Phenylbutazone monograph spanning p.1013-1014; page located 2026-08-05 from the book's own running heads, verified to name the drug in its body text. — SOURCE EDITION: Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207. Phenylbutazone is used in horses for Acute musculoskeletal pain, Musculoskeletal pain, laminitis. Routes documented in horses: IV, PO. A typical adult horse weighs 350.00–700.00 kg. ExoticRx lists 2 cited dose rules for Phenylbutazone in horses, drawn from published veterinary references. Verify against current literature before clinical use.
US trade names: Butazolidin
| Route | Dose | Frequency | Duration | Indication | Evidence | Source |
|---|---|---|---|---|---|---|
| IV | 4.4 mg/kg | q12h | Switch to oral ASAP | Acute musculoskeletal pain | Strong | Coleman MC. Laminitis. In: Smith BP, Van Metre DC, Pusterla N, eds. Large Animal Internal Medicine. 6th ed. St. Louis, MO: Elsevier; 2020:1235-1238. — Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.1042 (2026-08-01). — Plumb's 10th ed (held) printed p.1013, Phenylbutazone monograph spanning p.1013-1014; page located 2026-08-05 from the book's own running heads, verified to name the drug in its body text. — SOURCE EDITION: Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207 |
| PO | 4.4 mg/kg | q12h x2-3 d only, then taper to 2.2 mg/kg q12h | Use lowest effective dose | Musculoskeletal pain, laminitis | Strong | Appendix 3 - Drug doses and intervals for horses and ruminants. In: Constable PD, Hinchcliff KW, Done SH, Grünberg W, eds. Veterinary Medicine. 11th ed.: WB Saunders; 2017:2220-2231. — Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.1042 (2026-08-01). — Plumb's 10th ed (held) printed p.1013, Phenylbutazone monograph spanning p.1013-1014; page located 2026-08-05 from the book's own running heads, verified to name the drug in its body text. — SOURCE EDITION: Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207 |
Every held source for this drug and species, as printed. Where they differ, both are shown — the choice is yours, not ours.
| Dose (mg/kg) | Route | Source | As printed |
|---|---|---|---|
| 4.4–8.8 | PO | Papich Saunders Handbook of Veterinary Drugs, 4th edp.659 | • 4.4-8.8 mg/kg/day (generally 2 g to 4 g per horse) PO. Typically, a dose of |
| 4.4 | — | Papich Saunders Handbook of Veterinary Drugs, 4th edp.659 | 4.4 mg/kg is administered every 12 hours for the first 2-3 days, followed by a |
| 2.2 | — | Papich Saunders Handbook of Veterinary Drugs, 4th edp.659 | tapering dose to 2.2 mg/kg q12h. It is not recommended to use the highest |
| 2.2–4.4 | — | Papich Saunders Handbook of Veterinary Drugs, 4th edp.659 | • Injection: 2.2-4.4 mg/kg/day for 48-96 hours. Give injections intravenously |
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Non-selective COX inhibitor with potent anti-inflammatory and analgesic properties.
High toxicity in dogs (bone marrow aplasia, GI ulceration). Primarily used in horses and dogs. NEVER use in cats. Perivascular injection causes severe tissue necrosis.
Species-specific contraindications and adverse-reaction reports for horses may differ from canine / feline reference data — consult the primary citations listed with each rule.
Phenylbutazone dose ranges in horses, with cited source references: IV 4.4 mg/kg q12h; PO 4.4 mg/kg q12h x2-3 d only, then taper to 2.2 mg/kg q12h. Reference ranges from cited sources — verify against current literature before clinical use.
Documented routes for Phenylbutazone in horses: IV, PO.
Cited course lengths for Phenylbutazone in horses include: Switch to oral ASAP; Use lowest effective dose. Duration depends on the indication — match it to the specific dose rule in the table above.
Phenylbutazone is indicated in horses for: Acute musculoskeletal pain, Musculoskeletal pain, laminitis.
These are general warnings for Phenylbutazone across species; consult the horse dosing table above for species-specific guidance. High toxicity in dogs (bone marrow aplasia, GI ulceration). Primarily used in horses and dogs. NEVER use in cats. Perivascular injection causes severe tissue necrosis.
Why a species-specific page? Phenylbutazone pharmacokinetics differ across species: dose ranges, intervals, and route preferences are not interchangeable. Cross-extrapolation from canine doses is unsafe in horses — the rules above are the citations specific to this species, not generic recommendations.
Sourced from published veterinary references; awaiting credentialed clinical reviewer. See our editorial process. Reference only — not veterinary advice.
Figures are transcribed from the cited page or table of each held edition and are shown for reference only. They are not dose recommendations, they do not feed the calculator, and none has been reviewed by a veterinarian.