Skip to Content

The originating document has been archived. We cannot confirm the completeness, accuracy and currency of the content.


This page contains information on ThyroVet for veterinary use.
The information provided typically includes the following:
  • ThyroVet Indications
  • Warnings and cautions for ThyroVet
  • Direction and dosage information for ThyroVet


This treatment applies to the following species:
Manufacturer: VetOne

Levothyroxine Sodium Tablets, Usp

ThyroVet Caution

Federal law restricts this drug to use by or on the order of a licensed veterinarian.


For use only in dogs, under the care of a veterinarian.


Each Levothyroxine Sodium Tablet provides synthetic crystalline levothyroxine sodium (L-thyroxine).


Levothyroxine sodium acts, as does endogenous thyroxine, to stimulate metabolism, growth, development, and differentiation of tissues. It increases the rate of energy exchange and increases the maturation rate of the epiphyses. Levothyroxine sodium is absorbed rapidly from the gastrointestinal tract after oral administration. Following absorption, the compound becomes bound to the serum alpha globulin fraction. For purposes of comparison, 0.1 mg of levothyroxine sodium elicits a clinical response approximately equal to that produced by one grain (65 mg) of desiccated thyroid.


Provides thyroid replacement therapy in all conditions of inadequate production of thyroid hormones. Hypothyroidism is the generalized metabolic disease resulting from deficiency of the thyroid hormones levothyroxine (T4) and liothyronine (T3). Levothyroxine sodium will provide levothyroxine (T4) as a substrate for the physiologic deiodination to liothyronine (T3). Administration of levothyroxine sodium alone will result in complete physiologic thyroid replacement.

Canine hypothyroidism is usually primary, i.e., due to atrophy of the thyroid gland. In the majority of cases the atrophy is associated with lymphocytic thyroiditis; in the remainder it is non-inflammatory and of unknown etiology. Less than 10 percent of cases of hypothyroidism are secondary, i.e., due to deficiency of thyroid stimulating hormone (TSH). TSH deficiency may occur as a component of congenital hypopituitarism or as an acquired disorder in adult dogs, in which case it is invariably due to the growth of a pituitary tumor.

Hypothyroidism in the Dog:

Hypothyroidism usually occurs in middle-aged and older dogs, although the condition will sometimes be seen in younger dogs of the larger breeds. Neutered animals of either sex are also frequently affected, regardless of age. The following are clinical signs of hypothyroidism in dogs:

Lethargy, lack of endurance, increased sleeping; Reduced interest, alertness and excitability; Slow heart rate, weak apex beat and pulse, low voltage on ECG; Preference for warmth, low body temperature, cool skin; Increased body weight; Stiff and slow movements, dragging of front feet; Head tilt, disturbed balance, unilateral facial paralysis; Atrophy of epidermis, thickening of dermis; Surface and follicular hyperkeratosis, pigmentation; Puffy face, blepharoptosis, tragic expression; Dry, coarse, sparse coat, slow regrowth after clipping; Retarded turnover of hair (carpet coat of boxers); Shortening or absence of estrus, lack of libido; Dry feces, occasional diarrhea; Hypercholesterolemia; Normochromic, normocytic anemia; Elevated serum creatinine phosphokinase.


Levothyroxine sodium therapy is contraindicated in thyrotoxicosis, acute myocardial infarction, and uncorrected adrenal insufficiency. Use in pregnant bitches has not been evaluated.


The effects of levothyroxine sodium therapy are slow to manifest. Overdosage of any thyroid drug may produce the signs and symptoms of thyrotoxicosis, including but not limited to polydipsia, polyuria, polyphagia, reduced heat tolerance, and hyperactivity or personality change. Administer with caution to animals with clinically significant heart disease, hypertension, or other complications for which a sharply increased metabolic rate might prove hazardous.

Adverse Reactions:

There are no particular adverse reactions connected with L-thyroxine therapy at the recommended dosage levels. Overdose will result in signs of thyrotoxicosis listed above under Precautions.


The initial recommended dose is 0.1 mg/10 lb (4.5 kg) body weight twice daily. Dosage is then adjusted according to patient’s response by monitoring T4 blood levels at four-week intervals. The usual maintenance dose is 0.1 mg/10 lb (4.5 kg) once daily.


L-thyroxine tablets may be administered orally or placed in food.

Dosage forms available:

0.1 mg, 0.2 mg, 0.3 mg, 0.4 mg, 0.5 mg, 0.6 mg, 0.7 mg, and 0.8 mg tablets in bottles of 180 and 1000 ct. 1.0 mg tablets are available only in 1000 ct bottles.


Store at 20°-25°C (68°-77°F) with excursions between 15°-30°C (59°-86°F). Protect from light.


1. Evinger JV, Nelson RW. JAVMA 1984;185(3):314-316.

2. Nelson RW. In Kirk RW, ed. Current Veterinary Therapy X. Philadelphia: WB Saunders;1989:994.

3. Feldman E, Nelson RW. Canine and Feline Endocrinology and Reproduction. Philadelphia: WB Saunders;1987:82.

For Use In Animals Only.

Keep Out Of Reach Of Children.

Distributed by: MWI, Boise, ID 83705

(888) 694-8381


Manufactured by: Neogen Corporation, Lexington, KY 40511



Net Contents:



0.1 mg

180 Tablets


V1 510156

1000 Tablets


V1 510155

0.2 mg

180 Tablets


V1 510158

1000 Tablets


V1 510157

0.3 mg

180 Tablets


V1 510160

1000 Tablets


V1 510159

0.4 mg

180 Tablets


V1 510162

1000 Tablets


V1 510161

0.5 mg

180 Tablets


V1 510164

1000 Tablets


V1 510163

0.6 mg

180 Tablets


V1 510166

1000 Tablets


V1 510165

0.7 mg

180 Tablets


V1 510168

1000 Tablets


V1 510167

0.8 mg

180 Tablets


V1 510170

1000 Tablets


V1 510169

1.0 mg

1000 Tablets


V1 510171

Nac No.

Distributed by MWI Veterinary Supply

3041 W. PASADENA DR., BOISE, ID, 83705
Customer Service:   888-694-8381
Toll-Free:   800-824-3703
Every effort has been made to ensure the accuracy of the ThyroVet information published above. However, it remains the responsibility of the readers to familiarize themselves with the product information contained on the US product label or package insert.

Copyright © 2018 North American Compendiums. Updated: 2018-04-26