Dog Health & Safety

Symptoms of Thyroid Disease in Dogs – What to look out for

Thyroid problems can be relatively common in dogs. Just like us, these conditions are linked to a thyroid gland that doesn’t function as it should. There are two types of abnormality – hypothroidism and hyperthroidism. It may not surprize you to learn that the first is described us “underactive” and the latter as “overactive”. But how does this affect your dog and what are the symptoms you would see for each of these?


Noticing the first signs your dog might have a thyroid problem


A thyroid condition is definitely something that can just quietly sneak up on your dog, and might be hard to notice at first. Why? It’s becuase the symptoms can be quite subtle – just like in humans! My mother had hyperthyroidism, and it developed slowly over many years. So what are some of the signs your dog might start to show?

  1. Changes in activity levels or energy – for example, a “slowing” down compared to normal, or periods of over-exuberance. Think equivalent to a “sugar rush” in children!
  2. Weight changes, particularly if they don’t match your dog’s eating habits. For example, your dog is eating like a horse, but losing condition. Or vice versa, they may be eating less but putting on weight.
  3. Skin problems that have never bothered your dog before may develop

However, if you say these symptoms develop in your dog, you might associate them with something else. Afterall, these symptoms could fit with something else, and if they are only mild you may think there’s nothing really to worry about. However, a thyroid problem is easily diagnosed through a simple blood test. So if you have any inkling there may be something up with your dog, please mention it to your vet, who can easily perform the test for you. if it comes back positive, don’t fret, as thyroid conditions can be esaily treated with appropriate medication.

Let’s take a closer look at canine thyroid disease, and what it might mean for your dog.


What is a thyroid and what does it do?

The thyroid is a gland situated in your dog’s neck, which produces hormones in the body. This hormone production doesn’t really kick in until your dog reaches adulthood. Why does the body need these hormones? They are vital so food can be propoerly digested and important nutrients absorbed. They maintain the natural balance between food eaten and bodyweight.

If for some reason the gland prduces either too little (hypothroidism) or too much (hyperthyroidism) then things get out of sync and it impacts on the health of your dog. Left untreated, it will get more serious over time.

Sometimes thyroid problems can also be caused by cancer which also causes the gland to malfunction, and under- or over-produce levels of the hormones.

Let’s talk about the two different disease types, so you have more detail about what each one entails.

Symptoms of Hypothyroidism

An underactive thyroid gland is a relatively common illness in dogs. (Interestingly, it’s very rare in cats.) This means not enough of the hormones is being produced, so your dog’s metabolism slows right down. One of the main symptoms is therefore an increase in weight.

Hypothyroidism isn’t usually discovered until later in a dog’s life, probably becuase the gland doesn’t start functioning until your dog reaches maturity.

According to, “new research shows that 90 percent of hypothyroid cases are caused by a genetic autoimmune disease called thyroiditis, which produces antithyroid antibodies in the body and may begin to develop as early as puberty though clinical signs won’t appear for years”.

You may start to see signs and symtpoms between the ages of 4 and 10, and it’s more commonly seen in large breed dogs. Some of the main symptoms of hypothyroidism include:

  • Over-tiredness or lethargic behavior
  • Excessive shedding and/or hair loss
  • A coat that looks out of condition (i.e. drier than normal)
  • Sensitivity to the cold
  • Unwillingness to exercise
  • Behavior that is unusual for your dog, like sudden agrression

It’s important to note that not all dogs will show or experience all of these, and they may also be only very mild at the beginning.

If left untreated, and in serious onset, your dog could have seizures, an irregular heart rate, develop ulcers on their eyes, or even lose their sense of smell or taste. These are really unpleasant symptoms, so all the more reason to get an early diagnosis if at all possible.


Symptoms of Hyperthyroidism

An overactive thyroid gland is a lot less common in dogs, and more often seen in cats. In this case, too much hormone is produced and your dog’s metabloism goes into overdrive. (This is what my Mum had, and she described it as feeling like a constant stream of adrenaline running through her veins on a constant basis. As a result she constantly felt nervous and on edge)

Hyperthyroidism, if it does occur, is likely to be seen in older dogs. It is also liekly to develop at an even slower pace then hypothyroidism.

Some of the main symptoms of hypothyroidism include:

  • Weight loss or lack of body condition, and increased appetitie as a result as your dog tried to compensate
  • Higher haeart rate than usual
  • More frequent stops to the toilet (urination)
  • Bouts of being hyperactive
  • Increased irritation

How is a thyroid condition treated?

As I said above, a simple blood test is all that’s needed to diagnose a throid problem. The hormone levels in the blood sample are measured to determin if thay fall into a normal range or not.

If your dog is diagnosed with a thyroid disease, it’s likely they will have to be on medication to control the hormone levels for life.

Are some dogs more likely to have thyroid conditions?

More than 50 different breeds are genetically predispositioned to develop thyroid disease, so if you have one of those breeds consider early testing to catch the disease before it causes serious damage to your dog. Though symptoms may appear mild, untreated thyroid disease can cause long-term problems.

(see more at Symptoms of Thyroid Disease in Dogs –


Breeds that Have a High Incidence of Hypothyroidism

  • Beagles
  • Doberman Pinscher
  • Mixed Breeds
  • Labrador Retriever
  • Boxer
  • Terriers
  • Cocker Spaniel
  • Spaniels
  • German Shepherd
  • Rotweiler
  • Dachshund
  • Poodle

(via Thyroid Problems in Dogs: Issues and Treatment)


I hope you have found this useful, and if you have any comments, questions, or wish to share your own dog’s experiences, please do so below.

If in doubt, get your dog checked out…


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2 thoughts on “Symptoms of Thyroid Disease in Dogs – What to look out for

  1. Thank you so much for this article!!! I have a dog and now knowing the signs of a thyroid problem will definitely help. Right now she is only 2 years old but it is good to know this information for the future. I am definitely going to book mark this site and keep myself informed about what could possibly be going on with her health.

    1. Hi Mallory and thanks for your response to my article. I’m so glad you think this could be useful for the future. I hope you and your dog have a great summer, Mara.

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