Cat · Felis catus · typical adult weight 2.50–7.00 kg
Methimazole is dosed at 0.5–1 mg/kg PO q12h in cats, per Plumb's Veterinary Drug Handbook, 9th Ed. Methimazole is used in cats for Pre-surgical thyroidectomy stabilization, Hyperthyroidism (dose titration phase), Hyperthyroidism (alternative to oral). Routes documented in cats: PO, TRANSDERMAL. A typical adult cat weighs 2.50–7.00 kg. ExoticRx lists 3 cited dose rules for Methimazole in cats, drawn from published veterinary references. Verify against current literature before clinical use.
US trade names: Tapazole, Felimazole
| Route | Dose | Frequency | Duration | Indication | Evidence | Source |
|---|---|---|---|---|---|---|
| PO | 0.5–1 mg/kg | q12h | 2-4 weeks before surgery | Pre-surgical thyroidectomy stabilization | Strong | Plumb's Veterinary Drug Handbook, 9th Ed |
| PO | 0.25–0.5 mg/kg | q12h | Starting dose; recheck T4 at 2-3 weeks | Hyperthyroidism (dose titration phase) | Strong | Plumb's Veterinary Drug Handbook, 9th Ed |
| TRANSDERMAL | 0.5–1.5 mg/kg | q12h | Chronic | Hyperthyroidism (alternative to oral) | Strong | Plumb's Veterinary Drug Handbook, 9th Ed |
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These ranges are per kg. Enter your cat's weight to get the precise dose and draw-up volume — unit and concentration math done for you.
Inhibits thyroid peroxidase, blocking iodine organification and thyroid hormone synthesis. Does not destroy thyroid tissue.
Cats: monitor renal function (treating hyperthyroidism may unmask underlying renal disease). Side effects include anorexia, vomiting, facial pruritus, and blood dyscrasias. Monitor CBC and liver enzymes.
Species-specific contraindications and adverse-reaction reports for cats may differ from canine / feline reference data — consult the primary citations listed with each rule.
Methimazole dose ranges in cats, with cited source references: PO 0.5–1 mg/kg q12h; PO 0.25–0.5 mg/kg q12h; TRANSDERMAL 0.5–1.5 mg/kg q12h. Reference ranges from cited sources — verify against current literature before clinical use.
Documented routes for Methimazole in cats: PO, TRANSDERMAL.
Cited course lengths for Methimazole in cats include: 2-4 weeks before surgery; Starting dose; recheck T4 at 2-3 weeks; Chronic. Duration depends on the indication — match it to the specific dose rule in the table above.
Methimazole is indicated in cats for: Pre-surgical thyroidectomy stabilization, Hyperthyroidism (dose titration phase), Hyperthyroidism (alternative to oral).
These are general warnings for Methimazole across species; consult the cat dosing table above for species-specific guidance. Cats: monitor renal function (treating hyperthyroidism may unmask underlying renal disease). Side effects include anorexia, vomiting, facial pruritus, and blood dyscrasias. Monitor CBC and liver enzymes.
Why a species-specific page? Methimazole 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.