Benefits

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 bioavailability, 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.
• Thyro-Tabs tablets are manufactured and packaged to give an easier way to treat canine hypothyroidism and a more effective way to ensure compliance.

Nine Color-Coded Dosage Strengths

Protency	Color
0.1 mg (100 μg)	Yellow
0.2 mg (200 μg)	Pink
0.3 mg (300 μg)	Green
0.4 mg (400 μg)	Maroon
0.5 mg (500 μg)	White
0.6 mg (600 μg)	Purple
0.7 mg (700 μg)	Orange
0.8 mg (800 μg)	Blue
1.0 mg (1,000 μg)	Tan

Caution

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

Contraindications

Do not use in dogs with thyrotoxicosis or uncorrected adrenal insufficiency.

Warnings

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.

Human Warnings

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.

Precautions

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.

Adverse Reactions

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.

Effectiveness

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.

Animal Safety

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.

Storage

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.

Advantages

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 bioavailability, 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.

Nine Color-Coded Dosage Strengths

Protency	Color
0.1 mg (100 μg)	Yellow
0.2 mg (200 μg)	Pink
0.3 mg (300 μg)	Green
0.4 mg (400 μg)	Maroon
0.5 mg (500 μg)	White
0.6 mg (600 μg)	Purple
0.7 mg (700 μg)	Orange
0.8 mg (800 μg)	Blue
1.0 mg (1,000 μg)	Tan