Hypothyroidism in dogs
Hypothyroidism means the thyroid gland makes too little hormone, which slows the body's metabolism. It's most common in middle-aged dogs.
Last updated: October 2026 · 2 sources · see sources
Signs to watch for
- Weight gain without eating more
- Low energy
- Hair loss or a thin coat, often on the tail
- Skin infections
- Seeking warmth
Trouble breathing, collapse, repeated vomiting, not peeing, or a seizure that lasts more than a few minutes needs a vet right away. See when to see a vet.
How vets diagnose it
Your vet runs blood tests for thyroid hormone (T4, often with free T4 and TSH). One low number alone isn't enough, since other illnesses can lower it. [2]
How it's treated
Treatment is a daily thyroid hormone pill. Your vet rechecks blood levels to fine-tune it. [2]
Medicines your vet may mention: Levothyroxine. We don't list doses; your vet will decide what fits your pet.
What it costs to diagnose and manage
| Item | Typical US price | Src |
|---|---|---|
| Diagnosis (exam and tests) | $100–$300 | [1] |
| Ongoing treatment, per month | $20–$50 | [1] |
| First-year total | $400–$900 | [1] |
| Each year after that | $350–$800 | [1] |
These are typical US ranges from the sources listed. Your pet's costs depend on how severe things are, the tests your vet recommends, your pet's size and where you live. Ask your vet for a written estimate.
Outlook
Most dogs respond very well and feel more like themselves within weeks. Treatment is lifelong. [2]
Common questions
What is hypothyroidism in dogs?
Hypothyroidism means the thyroid gland makes too little hormone, which slows the body's metabolism. It's most common in middle-aged dogs.
What are the signs of hypothyroidism?
Common signs include: weight gain without eating more, low energy, hair loss or a thin coat, often on the tail, skin infections, seeking warmth.
How do vets diagnose hypothyroidism?
Your vet runs blood tests for thyroid hormone (T4, often with free T4 and TSH). One low number alone isn't enough, since other illnesses can lower it.
How is hypothyroidism treated?
Treatment is a daily thyroid hormone pill. Your vet rechecks blood levels to fine-tune it.
How much does hypothyroidism cost to treat?
Diagnosis (exam and tests): $100–$300; Ongoing treatment, per month: $20–$50; First-year total: $400–$900; Each year after that: $350–$800. Costs vary with severity, tests, your pet's size and where you live.
Related
This page is general information for pet owners, not veterinary advice. Talk to your vet about your own pet.