Cat · Felis catus · typical adult weight 2.50–7.00 kg
Fomepizole (4-MP) is dosed at 125 mg/kg IV Loading 125mg/kg, then 31.25mg/kg q12h x 3 doses in cats, per Connally HE, Thrall MA, Hamar DW. Safety and efficacy of high-dose fomepizole compared with ethanol as therapy for ethylene glycol intoxication in cats. J Vet Emerg Crit Care. 2010;20(2):191-206. doi:10.1111/j.1476-4431.2009.00492.x — Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.585 (2026-08-01). — Plumb's 10th ed (held) printed p.558, Fomepizole monograph; page located 2026-08-05 from the book's own running heads, and carries this exact dose under the matching species heading. — SOURCE EDITION: Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207. Fomepizole (4-MP) is used in cats for Ethylene glycol toxicosis. Routes documented in cats: IV. A typical adult cat weighs 2.50–7.00 kg. ExoticRx lists 1 cited dose rule for Fomepizole (4-MP) in cats, drawn from published veterinary references. Verify against current literature before clinical use.
US trade names: Antizol-Vet
| Route | Dose | Frequency | Duration | Indication | Evidence | Source |
|---|---|---|---|---|---|---|
| IV | 125 mg/kg | Loading 125mg/kg, then 31.25mg/kg q12h x 3 doses | Higher dose required in cats; 4-dose protocol over 36 hours | Ethylene glycol toxicosis | Moderate | Connally HE, Thrall MA, Hamar DW. Safety and efficacy of high-dose fomepizole compared with ethanol as therapy for ethylene glycol intoxication in cats. J Vet Emerg Crit Care. 2010;20(2):191-206. doi:10.1111/j.1476-4431.2009.00492.x — Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.585 (2026-08-01). — Plumb's 10th ed (held) printed p.558, Fomepizole monograph; page located 2026-08-05 from the book's own running heads, and carries this exact dose under the matching species heading. — 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.
The sources disagree for this combination. The ranges below do not overlap on a comparable route. This is not an error in one of them — published veterinary references differ, and reconciling them for a particular patient is a clinical judgement.
| Dose (mg/kg) | Route | Source | As printed |
|---|---|---|---|
| 125 | IV | BSAVA Small Animal Formulary, 10th ed — Part A (Canine and Feline)p.191 | 125 mg/kg slow i.v. then 31.25 mg/kg i.v. q12h for 3 additional doses. Efficacy has been shown if t |
| 31.25 | IV | BSAVA Small Animal Formulary, 10th ed — Part A (Canine and Feline)p.191 | 125 mg/kg slow i.v. then 31.25 mg/kg i.v. q12h for 3 additional doses. Efficacy has been shown if treated within 3 hours of i |
| 125 | — | Papich Saunders Handbook of Veterinary Drugs, 4th edp.372 | • 125 mg/kg initially, followed by 31.3 mg/kg at 12, 24, and 36 hours after the |
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Competitive inhibitor of alcohol dehydrogenase, preventing metabolism of ethylene glycol to toxic metabolites (glycolaldehyde, glycolic acid, oxalate).
Most effective within 8-12 hours of ethylene glycol ingestion in dogs (3 hours in cats). Cats require higher doses. Very expensive but life-saving.
Species-specific contraindications and adverse-reaction reports for cats may differ from canine / feline reference data — consult the primary citations listed with each rule.
Fomepizole (4-MP) dose range in cats, with cited source references: IV 125 mg/kg Loading 125mg/kg, then 31.25mg/kg q12h x 3 doses. Reference ranges from cited sources — verify against current literature before clinical use.
Documented routes for Fomepizole (4-MP) in cats: IV.
Cited course lengths for Fomepizole (4-MP) in cats include: Higher dose required in cats; 4-dose protocol over 36 hours. Duration depends on the indication — match it to the specific dose rule in the table above.
Fomepizole (4-MP) is indicated in cats for: Ethylene glycol toxicosis.
These are general warnings for Fomepizole (4-MP) across species; consult the cat dosing table above for species-specific guidance. Most effective within 8-12 hours of ethylene glycol ingestion in dogs (3 hours in cats). Cats require higher doses. Very expensive but life-saving.
Why a species-specific page? Fomepizole (4-MP) pharmacokinetics differ across species: dose ranges, intervals, and route preferences are not interchangeable. Cross-extrapolation from canine doses is unsafe in cats — 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.
| 31.3 |
| — |
| Papich Saunders Handbook of Veterinary Drugs, 4th edp.372 |
| • 125 mg/kg initially, followed by 31.3 mg/kg at 12, 24, and 36 hours after the |
| 31 | — | Papich Saunders Handbook of Veterinary Drugs, 4th edp.372 | detected. If analysis of ethylene glycol is not available, treat with 31 mg/kg every |
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.