Hypothyroidism in dogs – signs and what to do

Updated 2026-09-30 · 2 sources

Based on: PDSA, Science for Animal Welfare (UFAW), Genetic Welfare Problems of Companion Animals

Book a vet visit

Book a vet appointment if you think your dog has this – a vet needs to confirm it and plan the treatment. It is a condition involving the thyroid that can cause changes such as weight gain, low energy and fur loss.

What to do now

What you can do now

Contact your vet
Note when it started, how often it happens and what else you see
Take a photo or short video to show the vet
Keep fresh water available
Let your dog rest somewhere calm

Don't

Do not give any human medicine
Do not wait if it gets worse

What it is

Signs can be vague and usually develop gradually.^[1] Hypothyroidism can be treated with daily medication.^[1] Any breed can be affected, although Dobermanns and Boxers are among the breeds at higher risk.^[1]

Signs

Unexplained weight gain or difficulty losing weight
Fur loss
Low energy
Dandruff
Skin and ear infections
Thick skin around the face and a ‘sad’ expression
Feeling cold
Coma in severe cases

Causes and risk factors

Immune-mediated destruction
Idiopathic thyroid atrophy
Congenital hypothyroidism
Medications
Tumours
Radiation therapy

How a vet finds out

Blood tests

How vets treat it

Medication

Breeds prone to this

Veterinary charities list these breeds as more likely than others to get this condition. Each breed page lists the inherited conditions documented in the breed.

What the experts say

“Unexplained weight gain, or difficulty losing weight ; Alopecia (fur loss) ; L ethargy (low energy) ; Dandruff ; Skin and ear infections ; Thick skin around the face and a ‘sad’ expression ; Feeling cold ; Coma (in severe cases)”
— PDSA [1]

If your pet is struggling to breathe, has collapsed, is having a seizure or can't stand up: go to the nearest vet now.

Not sure how serious it is?

OkPaw asks a few quick questions about your pet and tells you in 30 seconds whether it can wait. Free on Google Play for Android.

OkPaw is on Android now – an iPhone version is on its way.

Common questions

What signs can hypothyroidism cause in dogs?

Signs can include unexplained weight gain or difficulty losing weight, fur loss, low energy, dandruff, skin and ear infections, thick skin around the face, a ‘sad’ expression and feeling cold.^[1]

How does a vet find out if a dog has hypothyroidism?

A vet may use blood tests to diagnose hypothyroidism.^[1]

How do vets treat hypothyroidism in dogs?

Vets treat hypothyroidism with daily medication to replace the missing thyroid hormones.^[1]

Sources

How this page was made: written with the help of AI from the sources below, then checked claim by claim against those sources. Urgency levels follow OkPaw’s fixed safety rules. It is guidance, not a diagnosis. How we write our pages