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Thyro-Tabs is a prescription medication for dogs that contains levothyroxine. Levothyroxine is a replacement for the hormone T-4, which is naturally produced in the body by the thyroid gland to regulate metabolism and energy. When the body is unable to produce enough thyroid hormone on it’s own because of an imbalance, an enlarged thyroid gland, or other medical conditions and treatments, it is called hypothyroidism. Hypothyroidism in dogs can be found with a blood test or by signs and symptoms involving metabolism, energy, nerve and muscle function, skin and haircoat. If your dog has been diagnosed with low thyroid hormone or hypothyroidism, your veterinarian may prescribe a levothyroxine medication such as Thyro-Tabs.
Levothyroxine Sodium Tablets (Thyro-Tabs) provides thyroid replacement therapy to pets with hypothyroidism or other thyroid conditions due to low circulating thyroid hormone.
For replacement therapy for diminished thyroid function in dogs.
View Thyro-Tabs Drug Facts Sheet.
The initial daily dose is 0.1 mg/10 pounds (0.01 mg/lb; 0.022 mg/kg) body weight as a single dose every 24 hours or as a divided dose every 12 hours. The dose may then be adjusted by monitoring the serum total thyroxine (TT4) concentrations 4 to 6 hours post-tablet administration, along with clinical response, of the dog every 4 to 8 weeks until an adequate maintenance dose is established. Due to potential differences in bio-availability, monitor serum TT4 concentrations and clinical response when switching from another levothyroxine sodium formulation to Thyro-Tabs Canine.
To minimize day-to-day variations in serum TT4 concentrations (see Clinical Pharmacology), owners should consistently administer Thyro-Tabs Canine either with or without food.
Federal (USA) law restricts this drug to use by or on the order of a licensed veterinarian.
Do not use in dogs with thyrotoxicosis or uncorrected adrenal insufficiency.
In humans and rodents, excess in uteroexposure to thyroid hormones is associated with hypothalamic-pituitary-thyroid axis dysfunction and morphologicalthyroid gland defects in the offspring. The safety of Thyro-Tabs Canine has not been evaluated in breeding, pregnant, or lactating dogs.
Not for use in humans. Keep out of reach of children. In the event of accidental ingestion, seek medical advice immediately and show the product label to the physician. Wash hands after handling.
Dogs with underlying cardiac disease that are diagnosed with hypothyroidism should be closely monitored during the dose establishment phase. Adjust-ment of cardiac medication or levothyroxine sodium dosage may be needed depending on clinical response.
In a 6-month US field study with 92 dogs, the most commonly reported adverse reactions by percentage of dogs experiencing the reaction included: anorexia (17%), dermatitis (15%), vomiting (15%), otitis externa (14%), lethargy (14%), polydipsia (13%), diarrhea (11%), leukocytosis (9%), pruritus (8%), tachypnea (8%), polyuria (5%), hyperactivity (4%), and seborrhea (1%).
One dog was withdrawn from the study at the owner's request because of increased water consumption and urination, which was possibly related to levothyroxine sodium.
Hematocrit and red blood cell counts exceeded the upper limit of the reference range in seven dogs by the end of the study. Liver enzyme (ALP, ALT, or AST) elevations related to levothyroxine administration were reported in three dogs. In two of the dogs with elevated ALT and AST, the elevations resolved by Day 70 and Day 126, respectively.
The following events were reported voluntarily to LLOYD, Inc. (as of 2015): Allergic-type hypersensitivity reactions (pruritus, hives, rash, facial swelling), alopecia, anorexia, vomiting, diarrhea, polyuria, polydipsia, hyperactivity, tachypnea, lethargy, collapse, and high or low serum total thyroxine concentrations.
For a copy of the Safety Data Sheet (SDS) or to report suspected adverse drug events, contact LLOYD, Inc. at 1-800-831-0004. For additional information about adverse drug experience reporting for animal drugs, contact FDA at 1-888-FDA-VETS or http://www.fda.gov/AnimalVeterinary/SafetyHealth.
In a US field study with 92 dogs, dogs were administered a starting daily dose of 0.1 mg/10 lb (0.022 mg/kg) body weight. The dose was administered either once every 24 hours or as 0.05 mg/10 lb (0.011 mg/kg) body weight every 12 hours. The dose could be increased or decreased (without a change in frequency) after 6, 10, and 18 weeks, based on clinical findings and serum thyroid hormone concentrations. The majority of the dogs (80%) were dosed at 0.08-0.12 mg/10 lb (0.008-0.012 mg/lb; 0.018-0.026 mg/kg) by the end of the study, with the majority of dogs (69.7%) requiring one dose change.
The product was considered effective if the serum TT4, free thyroxine (fT4), and thyroid stimulating hormone (TSH) concentrations were all within the desired treatment ranges when collected 4 to 6 hours post-tablet administra-tion after 182 ± 5 days of treatment (TT4: 15-94 nmol/L; fT4: 8-36 pmol/L; TSH: ≤ 37 mU/L). Of the 78 evaluable cases, 59 (75.6%) were considered treatment successes. There was no statistical difference in the success rate between the once daily or divided dose treatment groups.
Clinical signs of hypothyroidism (weight gain, lethargy, bradycardia, seborrhea, alopecia, hyperpigmentation, scaling, and hypercholesterolemia) generally improved by the end of the study (Day 182 ± 5). Respiratory rate, excluding panting dogs, increased during the study along with activity level.
In a laboratory study, levothyroxine sodium was administered to 32 healthy, 7-10 month old, euthyroid Beagle dogs (4 males and 4 females per group) at 0X, 2X, 6X, and 10X the initial dose of 0.10 mg/10 lb (0.01 mg/lb) once daily for 26 weeks. Increased serum TT4 and fT4 concentrations were directly propor-tional to an increasing dose of levothyroxine sodium.
Decreased serum TSH concentrations were inversely proportional to an increasing dose of levothyroxine sodium. Dogs treated with levothyroxine sodium had elevated red blood cell indices (hemoglobin, hematocrit, and red blood cell count) and ALT but these did not exceed the normal reference ranges. Dogs treated with levothyroxine sodium had lower albumin, calcium, globulins, and total protein values but these did not fall below the normal reference ranges. Vomiting, diarrhea, excitation, rapid respiration, tachycardia, and feces with blood were observed in all treatment groups, but were seen with greater frequency in dogs treated with levothyroxine sodium. Decreased pituitary gland and thy-roid/parathyroid gland organ weights were also observed in euthyroid dogs treated with levothyroxine sodium.
Store at controlled room temperature 20°-25°C (68°-77°F) with excursions allowed between 15° and 30°C (59° and 86°F). Protect from light and moisture.