Hypothyroidism in Yorkshire Terriers
Endocrine condition — Yorkshire Terrier — Small breed
Moderate Risk
What is Hypothyroidism?
Hypothyroidism occurs when the thyroid gland produces insufficient thyroid hormone, slowing the dog's metabolism. It is the most commonly diagnosed hormonal disease in dogs. Most cases result from immune-mediated destruction of the thyroid gland (lymphocytic thyroiditis), which has a heritable component in several breeds.
Symptoms of Hypothyroidism
- Weight gain without increased food intake
- Lethargy and exercise intolerance
- Hair loss, especially on the trunk and tail base
- Dry, dull coat
- Thickened or darkened skin
- Cold intolerance
- Slow heart rate
- Mental dullness
How Is Hypothyroidism Diagnosed?
Blood test measuring total T4 (thyroxine) is the initial screen. A low T4 with consistent clinical signs supports diagnosis. Confirmatory testing with free T4 by equilibrium dialysis or TSH measurement improves accuracy. OFA maintains a thyroid registry.
Treatment & Cost
Daily oral levothyroxine (synthetic T4) supplementation. Very affordable — typically $20–$60/month depending on dose and dog size. Clinical signs resolve completely with correct dosing. Periodic T4 monitoring (every 6 months once stable) is required for life.
Most pet insurance plans cover hypothyroidism treatment in full when the policy is active before diagnosis. Compare plans below.