Question 1

What is Levothyroxine used for?

Accepted Answer

Levothyroxine is indicated for: Hypothyroidism, Iatrogenic hypothyroidism (post-I131 or surgery).

Question 2

What routes can Levothyroxine be administered by?

Accepted Answer

Available routes: PO, IV.

Question 3

Which species have cited Levothyroxine dosing data?

Accepted Answer

Levothyroxine dosing in the ExoticRx formulary covers 2 species: Cat (Domestic), Dog (Domestic).

Question 4

Is Levothyroxine a controlled substance?

Accepted Answer

Levothyroxine is not federally scheduled as a controlled substance, but is veterinary prescription only in most jurisdictions.

Question 5

What are the warnings or contraindications for Levothyroxine?

Accepted Answer

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.

Question 6

What are the side effects of Levothyroxine?

Accepted Answer

Reported side effects, adverse reactions, and contraindications for Levothyroxine: 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.

Question 7

How does Levothyroxine work?

Accepted Answer

Synthetic T4 (thyroxine) that is converted to active T3 in peripheral tissues. Restores normal metabolic rate, thermogenesis, and organ function.

Species	Route	Dose	Frequency	Evidence	Source
Dog (Domestic)	PO	0.02 mg/kg	q12h	Strong	Plumb's Veterinary Drug Handbook, 9th Ed
Cat (Domestic)	PO	0.05–0.1 mg per cat	q24h	Moderate	Plumb's Veterinary Drug Handbook, 9th Ed

Levothyroxine

Drug Class

Routes

Indications

Mechanism of Action

Side effects & warnings

Species with Levothyroxine dosing data (2 dose rules)

Evidence levels across 2 dose rules

Backed by a published source

Sample dosing (2 of 2 cited rules)

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