Dog Health & Care

Hypothyroidism in dogs: Symptoms and Treatments

When the surprising diagnosis of hypothyroidism in the family dog comes across the desk of the family vet after a blood test, most dog owners leave the office feeling slightly shell-shocked.

What is surprising is that the symptoms of hypothyroidism have probably have been in the making for awhile, as most under-active thyroids are seen in dogs who have gained weight while having very little energy. Other symptoms are involved but are seen as variables unless clumped together.

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Thyroid hormones are important in regulating the metabolism of individual cells in the dog’s body, produced in thyroid glands located on both sides of the animal’s windpipe trachea.

In addition to normal, metabolism rates can either be too high or too low. If it is too high, the dog will eat and eat yet lose weight rapidly. If it is too low, the overweight dog will eat very little yet gain weight rapidly while having very low energy levels.

Symptoms of under-active thyroids in dogs

The symptoms of hypothyroidism in dogs varies with the dog. And on a one-to-one basis they do not mean as much as when several symptoms are seen together in the dog.

  • Over 80% of dogs test for high blood cholesterol
  • Over 70% of dogs show mental sluggishness and lethargy as a number one symptom
  • Hair loss (65%)
  • Obesity or a substantial gain in weight above normal (60%)
  • Shedding of hair or excessive dry hair (60%)
  • Dogs test for anemia (50%)
  • A fewer percentage develop cold intolerance (15%); slow heart rate (10%); and hyper-pigmentation of the skin (25%).

Treatment for hypothyroidism in dogs

The treatment for hypothyroidism in dogs is not only inexpensive but easily treated with a pill[s] called thyroxine (levothyroxine) which is a synthetic thyroid hormone. A brand name could be Thyrosyn in .2 mg tablets with twice a day dosages. Each dosage will vary on how severe the disease is, in addition to how well the dog responds to it.

The initial standard dose will begin with the dog’s weight. After this,  routine blood tests are taken periodically to see how it is working. The test results will decide if the drug dosage needs to be adjusted. Once treatment for hypothyroidism in dogs  is begun, most of the symptoms will go away. However the dog will need to be on medication for life.


(This article is dedicated to Julie, one of our Miniature American Eskimos who lives in Pennsylvania with her owner, Frank. She has recently been diagnosed with an under-active thyroid.)

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  1. Azanokij
    August 28, 2017 at 2:47 pm — Reply

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    • September 18, 2017 at 10:43 am — Reply

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  2. Mindy
    October 29, 2010 at 12:22 pm — Reply

    They did work well for my dog, especially the thyroid extract. They are made by Standard Process. I just bought the human formula and split the tablets. They do have vet formulas, but it just seemed like they were more expensive for smaller doses and smaller quantities. There are probably some other differences, but I just went with the human formulas. My dog ranged from 25-40 pounds (40 before thyroid diagnosis and 25 after all illnesses including diabetes and kidney problems). It might be difficult using the human formulas for a really small dog because of splitting pills into more pieces might not be very accurate.

    It’s been so long ago that I don’t remember how I even came across the Thytrophin in the first place (around the year 2000). They worked incredibly well for my dog. Years later I tried the adrenal extracts (posted on the Cushings discussion). They helped keep some symptoms at bay for a while but didn’t have quite the extreme result as the thyroid supplements. They make a LOT of different types of supplements for pretty much everything (seems like it), but those are the only two that I can recall trying.

    • October 29, 2010 at 12:47 pm — Reply

      What makes this important is that it actually worked for your dog, it is not just a theory.

  3. Mindy
    October 29, 2010 at 11:33 am — Reply

    I had a dog with hypothyroidism. She was originally on thyroxin. I then changed her to the natural supplement Thytrophin PMG, which is a bovine thyroid extract. Her levels were actually regulated much better with the Thytrophin. I just had to get tests every few months early on to make sure I had the dosage right. She lived for MANY years with it and levels were always in the normal range with treatment.

    • October 29, 2010 at 11:56 am — Reply


      The bovine supplements are something that must work well with dogs, right? I have seen you mention it a couple times now in your comments. I may have to check on it for a post, seeing what I can find out.

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