Hypothyroidism in Dogs

What is hypothyroidism?

The thyroid is a small gland in the neck. It makes thyroid hormone, which sets how fast the body uses energy. In hypothyroidism, the gland makes too little hormone, and the body slows down.

In most dogs, the cause is damage to the thyroid gland itself, often because the dog's own immune system attacks it, or because the gland shrinks for unknown reasons. It is most common in middle-aged dogs, and medium and large breeds are often affected. The changes come on slowly, so owners may first think their dog is simply getting older.

Signs to watch for

Common signs include:

• Weight gain without eating more
• Low energy and sleeping more
• Seeking warm places
• Hair loss on the body or tail
• A dry, dull coat that grows back slowly
• Repeated skin or ear infections

Many of these signs can also come from other illnesses, so testing matters.

Which lab tests help

Thyroid testing in dogs needs care, because many other illnesses can lower thyroid results in a dog whose thyroid is healthy. Tell your vet about every tablet, injection or supplement your dog is getting, as some can affect the results too.

A total T4 test, such as the Canine Specific T4, is often the first step. It measures the main thyroid hormone. A normal T4 makes hypothyroidism unlikely, but a low T4 alone is not enough to confirm it.

The T4 Free (FT4) measures the part of the hormone that is free to act, and is often added to help confirm the result. The Canine Specific TSH measures TSH, a hormone from the pituitary gland at the base of the brain that tells the thyroid to work. In many hypothyroid dogs, TSH is high while T4 is low, but a normal TSH does not rule the disease out. Panels such as the Thyroid Profile Panel-2 (T4, FT4, TSH & Cholesterol) combine these tests.

Cholesterol Total is often high in dogs with hypothyroidism, and a Complete Blood Count (CBC) may show mild anaemia. These findings support the diagnosis but do not prove it. If your dog is already being treated for a thyroid problem, ask your vet when to take the follow-up sample.

A registered veterinarian interprets the results as a set, together with the dog's signs and history.

When to see your vet

See your vet promptly if your dog is gaining weight, losing hair, tiring easily or getting repeated skin or ear infections. These changes come on slowly, so compare your dog with how it was a few months ago. A dog that is very weak, collapses or seems suddenly unwell needs a vet the same day.

Testing in Bhopal

Pashupatinath Vet Lab is at C-200, C Sector, Shahpura, Bhopal, and thyroid samples are collected free anywhere in Bhopal. Dog owners in other districts can send samples through their local vet, by courier or by bus parcel, after a call or WhatsApp message to +91 88175 01118. The lab confirms the method, sample needs and reporting time when you book. Reports reach you on WhatsApp, by e-mail and in My Reports on the website.