Cat · Felis catus · typical adult weight 2.50–7.00 kg
Levothyroxine is dosed at 0.05–0.1 mg per cat PO q24h in cats, per Scott-Moncrieff JC. Chapter 3: Hypothyroidism. In: Canine and Feline Endocrinology. 4th ed. Elsevier Saunders; 2015.; Peterson ME, Carothers MA, Gamble DA, Rishniw M. Spontaneous primary hypothyroidism in 7 adult cats. J Vet Intern Med. 2018;32(6):1864-1873. doi:10.1111/jvim.15417 — Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.778 (2026-08-01). — Plumb's 10th ed (held) printed p.749, Levothyroxine monograph spanning p.749-751; 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. Levothyroxine is used in cats for Iatrogenic hypothyroidism (post-I131 or surgery). Routes documented in cats: PO. A typical adult cat weighs 2.50–7.00 kg. ExoticRx lists 1 cited dose rule for Levothyroxine in cats, drawn from published veterinary references. Verify against current literature before clinical use.
US trade names: Soloxine, Thyro-Tabs
| Route | Dose | Frequency | Duration | Indication | Evidence | Source |
|---|---|---|---|---|---|---|
| PO | 0.05–0.1 mg per cat | q24h | Long-term | Iatrogenic hypothyroidism (post-I131 or surgery) | Moderate | Scott-Moncrieff JC. Chapter 3: Hypothyroidism. In: Canine and Feline Endocrinology. 4th ed. Elsevier Saunders; 2015.; Peterson ME, Carothers MA, Gamble DA, Rishniw M. Spontaneous primary hypothyroidism in 7 adult cats. J Vet Intern Med. 2018;32(6):1864-1873. doi:10.1111/jvim.15417 — Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.778 (2026-08-01). — Plumb's 10th ed (held) printed p.749, Levothyroxine monograph spanning p.749-751; 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 (mcg/kg) | Route | Source | As printed |
|---|---|---|---|
| 10–20 | PO | Papich Saunders Handbook of Veterinary Drugs, 4th edp.475 | • 10-20 mcg/kg/day (0.01-0.02 mg/kg) PO (adjust dose via monitoring). L |
| Dose (mg/kg) | Route | Source | As printed |
|---|---|---|---|
| 0.01–0.02 | PO | Papich Saunders Handbook of Veterinary Drugs, 4th edp.475 | • 10-20 mcg/kg/day (0.01-0.02 mg/kg) PO (adjust dose via monitoring). L |
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.
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Synthetic T4 (thyroxine) that is converted to active T3 in peripheral tissues. Restores normal metabolic rate, thermogenesis, and organ function.
Dose based on body weight, adjusted by monitoring serum T4 levels (4-6 hour post-pill sample). Give on empty stomach. Monitor for signs of thyrotoxicosis (tachycardia, panting, anxiety). Dogs primarily.
Species-specific contraindications and adverse-reaction reports for cats may differ from canine / feline reference data — consult the primary citations listed with each rule.
Levothyroxine dose range in cats, with cited source references: PO 0.05–0.1 mg per cat q24h. Reference ranges from cited sources — verify against current literature before clinical use.
Documented routes for Levothyroxine in cats: PO.
Cited course lengths for Levothyroxine in cats include: Long-term. Duration depends on the indication — match it to the specific dose rule in the table above.
Levothyroxine is indicated in cats for: Iatrogenic hypothyroidism (post-I131 or surgery).
These are general warnings for Levothyroxine across species; consult the cat dosing table above for species-specific guidance. Dose based on body weight, adjusted by monitoring serum T4 levels (4-6 hour post-pill sample). Give on empty stomach. Monitor for signs of thyrotoxicosis (tachycardia, panting, anxiety). Dogs primarily.
Why a species-specific page? Levothyroxine 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.