Hypothyroidism

Endocrine and MetabolicCanineNew

Key Points

Hypothyroidism is an endocrinopathy caused by low thyroid hormone levels (mainly T3 and T4)
- Thyroid hormones play a key role in regulating metabolism, skin health, cardiovascular function, neuron function and lipid metabolism
Most commonly seen in dogs, especially middle-old age larger breeds
Key clinical signs include lethargy, weight gain, exercise intolerance, bilateral alopecia and recurrent skin problems / infections
Low tT4 levels alone are not diagnostic and must be interpreted alongside compatible clinical signs and other thyroid function tests
- Euthyroid sick syndrome / non-thyroidal illness can occur and this is when an underlying condition causes low thyroid hormone levels despite normal thyroid gland function
Treatment is lifelong supplementation with levothyroxine

Differential Diagnoses

Cushing’s disease (hyperadrenocorticism)
Atopic dermatitis
Diabetes mellitus

Educational content only. This factsheet is for general veterinary education and is not a substitute for professional veterinary advice, diagnosis, or treatment. Not for use in an emergency — contact a veterinarian or emergency service. Full disclaimer →