Sourced from published veterinary references. Awaiting credentialed clinical reviewer — our editorial process.
Levothyroxine is dosed at 10–20 ug/kg PO q24h in guinea pigs, per Ewringmann A, Gloeckner B. Leitsymptome bei Meerschweinchen, Chinchilla und Degu, Enke, Stuttgart, Germany; 2012. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.801 — Carpenter's Exotic Animal Formulary 6th ed, Table 9.7 (Miscellaneous Agents Used in Rodents). Verify against current literature before clinical use.
HypothyroidismIatrogenic hypothyroidism (post-I131 or surgery)induction of moultlifetime managementmay induce moltPost-thyroidectomy hormone replacementthyroid supplementation
Mechanism of Action
Synthetic T4 (thyroxine) that is converted to active T3 in peripheral tissues. Restores normal metabolic rate, thermogenesis, and organ function.
Side effects & warnings
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 with Levothyroxine dosing data (16 dose rules)
Each ExoticRx dose rule is graded by the strength of its primary evidence — see the editorial process.
Sample dosing (2 of 16 cited rules)
A dog/cat sample is shown here. Cited dosing for all 16 species — reptiles, birds, pocket pets, livestock, and equine — is free on the per-species pages above. Pro adds the weight-based calculator for every species.
Plumb's 10th ed printed p.749, Levothyroxine monograph spanning p.749-751.Compilation only — we have not located an independent source that prints this figure.
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· 43. Bailey TA, Apo MM. Pharmaceutics commonly used in avian medicine. In: Samour J, eds. Avian Medicine, 3rd ed., Mosby Elsevier, Edinburgh, Scotland; 2016:637-678. | 159. Formulary. In: Chitty J, Lierz M, eds. BSAVA Manual of Raptors, Pigeons and Passerine Birds; British Small Animal Veterinary Association, Gloucester, UK; 2008:384-390. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.463 — Carpenter's Exotic Animal Formulary 6th ed, Table 5.7 (Hormones and Steroids Used in Birds).
· 43. Bailey TA, Apo MM. Pharmaceutics commonly used in avian medicine. In: Samour J, eds. Avian Medicine, 3rd ed., Mosby Elsevier, Edinburgh, Scotland; 2016:637-678. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.463 doi:10.1016/b978-0-7234-3832-8.00023-7 — Carpenter's Exotic Animal Formulary 6th ed, Table 5.7 (Hormones and Steroids Used in Birds). — LEADING REFERENCE IS WRONG FOR THIS FIGURE (10x). The served 20 micrograms/kg is CORRECT and does not move - Carpenter 6th ed Table 5.7 (Hormones and Steroids Used in Birds) prints "20 ug/kg PO q12-24h43,159,391 | Most species, including psittacines, pigeons, and raptors", and BSAVA Small Animal Formulary Part B printed p.179 independently prints "Birds: 0.02 mg/kg p.o. q12-24h. Dissolve 1 mg in 28.4 ml water and give 0.4-0.5 ml/kg q12-24h." But the cited leading reference - Bailey TA and Apo MM, Pharmaceutics commonly used in avian medicine, in Samour J ed, Avian Medicine 3rd ed, Mosby Elsevier, 2016:637-678 - prints levothyroxine TWICE at printed p.665 and BOTH times at 0.2 mg/kg PO q12-24h, ten times the served figure. LEAD WITH the BSAVA Part B monograph, which we hold and which prints the exact served figure, and keep Bailey and Apo only as a recorded disagreement so it is not silently re-added.
· 43. Bailey TA, Apo MM. Pharmaceutics commonly used in avian medicine. In: Samour J, eds. Avian Medicine, 3rd ed., Mosby Elsevier, Edinburgh, Scotland; 2016:637-678. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.463 — Carpenter's Exotic Animal Formulary 6th ed, Table 5.7 (Hormones and Steroids Used in Birds).
· 781. Rosenthal KL, Johnston M. Hypothyroidism in a red-lored Amazon (Amazona autumnalis). Proc Annu Conf Assoc Avian Vet; 2003:33-36. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.463 — Carpenter's Exotic Animal Formulary 6th ed, Table 5.7 (Hormones and Steroids Used in Birds). — SOURCE ROW: Carpenter's Exotic Animal Formulary 6th ed — "Levothyroxine (l-thyroxine). 5-200 ug/kg PO. Amazon parrots. May induce molt; monitor […]"
· Ewringmann A, Gloeckner B. Leitsymptome bei Meerschweinchen, Chinchilla und Degu, Enke, Stuttgart, Germany; 2012. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.801 — Carpenter's Exotic Animal Formulary 6th ed, Table 9.7 (Miscellaneous Agents Used in Rodents).
· Franco KH and Hoover JP (2009) Leveothyroxine as a treatment for presumed hypothyroidism in an adult male African spurred tortoise. Journal of Herpetological Medicine and Surgery 19(2), 47-49 — Source: BSAVA Small Animal Formulary, 10th Ed, Part B: Exotic Pets, p.194
· Hadfield CA, Clayton LA, Clancy MM. Proliferative thyroid lesions in three diplodactylid geckos: Nephrurus amyae, Nephrurus levis, and Oedura marmorata. J Zoo Wildl Med. 2012,43:131-140. - Carpenter's Exotic Animal Formulary 6th ed, Table 4.8 (Hormones and Steroids Used in Reptiles): 'Levothyroxine | 0.02 mg/kg PO q48h172 | Geckos/post thyroidectomy, lifetime management'.' is REMOVED - no fish text bears on a gecko thyroid row.
· Hadfield CA, Clayton LA, Clancy MM. Proliferative thyroid lesions in three diplodactylid geckos: Nephrurus amyae, Nephrurus levis, and Oedura marmorata. J Zoo Wildl Med. 2012;43:131-140. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.260 doi:10.1638/2011-0106.1 — Carpenter's Exotic Animal Formulary 6th ed, Table 4.8 (Hormones and Steroids Used in Reptiles).
· Meredith A. BSAVA Small Animal Formulary: Part B: Exotic Pets, British Small Animal Veterinary Association, Quedgeley, Gloucester, UK; 2015. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.801 — Carpenter's Exotic Animal Formulary 6th ed, Table 9.7 (Miscellaneous Agents Used in Rodents).
· Plumb's 10th ed printed p.749, Levothyroxine monograph spanning p.749-751.
· 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 — Plumb's 10th ed printed p.749, Levothyroxine monograph spanning p.749-751.