Active form of thyroid hormone that binds nuclear thyroid hormone receptors (TR), directly regulating gene transcription involved in metabolism, growth, and development. Does not require peripheral conversion (unlike T4/levothyroxine). Rapid onset, short half-life.
At a glance
Class
Thyroid Hormone (Triiodothyronine)
Storage
Store at room temperature, protect from light and moisture
Dosing
Used for hypothyroidism refractory to levothyroxine (T4), or when T4-to-T3 conve
Used diagnostically — T3 suppression test differentiates euthyroid sick from occ
Frequency
q8h (diagnostic test)
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet.
Find a vet near you →Safety
Total T3 levels 4–6h post-doseHeart rateBody weightClinical response
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet.
Find a vet near you →Interactions
No documented interactions.
FAQs
Frequently asked questions
›What is Liothyronine (T3)?
Liothyronine (T3) is a thyroid hormone (triiodothyronine) used in pets. Active form of thyroid hormone that binds nuclear thyroid hormone receptors (TR), directly regulating gene transcription involved in metabolism, growth, and development. Does not require peripheral conversion (unlike T4/levothyroxine). Rapid onset, short half-life.
›What is Liothyronine (T3) used for in pets?
Liothyronine (T3) is used in veterinary medicine for: Used for hypothyroidism refractory to levothyroxine (T4), or when T4-to-T3 conve; Used diagnostically — T3 suppression test differentiates euthyroid sick from occ.
›What is the Liothyronine (T3) dose for dogs?
For dogs, Liothyronine (T3) is typically dosed as follows — Used for hypothyroidism refractory to levothyroxine (T4), or when T4-to-T3 conve: 4–6 mcg/kg PO q8h. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›What is the Liothyronine (T3) dose for cats?
For cats, Liothyronine (T3) is typically dosed as follows — Used diagnostically — T3 suppression test differentiates euthyroid sick from occ: undefined undefined PO q8h (diagnostic test). Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›Does Liothyronine (T3) need a prescription?
Yes. Liothyronine (T3) is a prescription medication and should only be administered under veterinary supervision.
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet.
Find a vet near you →References
References
The PetCare.AI drug reference is built from 13 authoritative sources cited across 580 drug monographs.
Textbooks & handbooks — 5
- Plumb's Veterinary Drug Handbook
- Withrow & MacEwen's Small Animal Clinical Oncology
- Merck Veterinary Manual
- NRC Nutrient Requirements of Dogs and Cats
- Veterinary Pharmacology and Therapeutics (Riviere & Papich)
Clinical guidelines & consensus — 4
- ASPCA Animal Poison Control Center Guidelines
- AAHA Diabetes Management Guidelines
- ASPCA Poison Control Guidelines
- RECOVER CPR Guidelines
Journals & peer-reviewed studies — 2
- EPIC Study (J Vet Intern Med 2016)
- JVIM FAT CAT Study
Regulatory & approvals — 1
- CDSCO Veterinary Drug Approval Registry (1969–2026)
Databases — 1
- Washington State University VCPL MDR1 Database