476 Myrtle Ave

Brooklyn, NY 11205 US

(718) 623-3999

Open mobile navigation

Hypothyroidism

Image of a dog.

Hypothyroidism is the natural deficiency of thyroid hormone and is the most common hormone imbalance of dogs. This deficiency is produced by several different mechanisms. The most common cause (at least 95% of cases) is immune destruction of the thyroid gland. It can also be caused by natural atrophy of the gland, by dietary iodine deficiency, neoplasia (primary or metastatic) of the thyroid gland or (rarely) as a congenital problem. Hypothyroidism is most common in medium to large breeds of dogs that are middle aged (4 to 10 years) but can occur in any dog.

Hypothyroidism is extremely rare in cats and is most commonly seen in cats following bilateral thyroid removal or radioactive iodine therapy for hyperthyroidism. This is often transient and usually does not require therapy. Rarely cats can have congenital hypothyroidism.

Thyroid hormone serves as a sort of volume dial for metabolism. Since virtually every cell in the body can be affected by thyroid hormone it is not surprising that reduced levels of thyroid hormone can lead to symptoms in multiple body systems. A recent published survey of hypothyroid dogs showed the following percentages of symptoms:

88% had some kind of skin abnormality
40% had hair loss (often on the tail or on both sides of the trunk and flanks ).
22% had skin infections
14% had dry brittle coats with hair that could easily be pulled out
49% were obese
48% were described as lethargic or listless at home
36% were anemic
80% had an increase in blood cholesterol

Hypothyroidism is treated with the oral administration of thyroid hormone, usually given twice daily for the life of the dog. Periodic blood testing is recommended; it is important to know if the medication dose is too low or too high. Thyroid supplement is a safe medication but if it is not given in sufficient doses the patient will not be adequately treated. If the dose is too high excessive water consumption, weight loss, and restlessness can result. Once a pet is started on thyroid supplementation, it is recommended to check a T4 level in two to three weeks, with the blood draw between 4 to 6 hours after the morning dose.Once the correct dose is found, it is recommended to perform a T4 every six to twelve months.

Hyperthyroidism in Cats

This is a very common disease of the middle aged to older cat. A tumor (97% are benign) on the thyroid gland starts producing too much thyroid hormone. Symptoms are usually weight loss in spite of eating well and vomiting. Other signs you might see are diarrhea, a dull and flaky hair coat, and personality changes. This disease usually can be easily diagnosed with a blood test, although occasionally we need a special test called a technesium scan to diagnose the early, borderline cases.

There are three basic methods of treatment: radioactive iodine, surgery, or an oral medication called methimazole (Tapazole). For most cats, the best treatment is radioactive iodine. In 97% of the cases, it is a one-time treatment. The biggest disadvantage is that the treatment needs to be done at a special facility, and the cat needs to be hospitalized for usually 5 to 10 days. In the past, surgery was a common treatment, but it is performed less frequently as the problem seems to recur on the other gland. Treating with Tapazole is also common, but has the disadvantage that it is life long and the cat needs blood tests to monitor the thyroid level and to check for adverse effects.

The disease of hyperthyroidism can actually help the kidneys. If the cat has both kidney disease and hyperthyroidism, it is not a candidate for radioactive iodine and the dose of Tapazole may need to be adjusted. Kidney tests are also monitored when a cat is being treated for hyperthyroidism.

New to Clinton Hill Animal Clinic?

Sign-up to request more information!

Office Hours

Monday:

10:30 am-5:30 pm

Tuesday:

10:30 am-5:30 pm

Wednesday:

10:30 am-5:30 pm

Thursday:

Closed

Friday:

10:30 am-5:30 pm

Saturday:

10:30 am-5:30 pm

Sunday:

Closed

Phone: (718) 623-3999
476 Myrtle Ave, Brooklyn, NY, 11205, US


Location

Find us on the map

Testimonials

Read What Our Clients Say

  • "Roxy and i loved our experience with Clinton hill, and our doctor was amazing! She explained everything and answered all my questions. I highly recommend this vet clinic!"
    Amanda Hodge
  • "Always excellent professional care. Staff are empathetic towards pets and pet parents. I highly recommend this clinic. My dogs have been under care there for the past eight years."
    Frances Haile
  • "I wish there was a way to give 10 stars. It was the absolute best experience for us and our cats. The guy it the front desk I’m so sorry I forgot your name but he was extremely patient, thorough and took the time to answer every question we had. The doctor was caring and extremely knowledgeable about cats. It was the best experience 10 stars!"
    Brian Bee
  • "This place specializes in creating great relationships with owners and pets. I've been with Dr. Pamela Dendtler since 2003 ! Awesome care and service."
    Diedre Yvonne Gary
  • "To Dr Dendtler and Staff, I cant begin to tell you how impressed I am with the loving care you have given to my cat Baxter, before and after the much needed surgery. Baxter is so pleased with the outcome; he goes around purring all day."
    Thanks again. -Estelle P.
  • "Dear Dr. Dendtler, You were very thorough and caring in treating Buddy. You explained clearly how to protect my dog. I have been to many clinics but you are the best. You were very professional and compassionate. Buddy and I are very grateful. Thanks ever so much to you and your staff."
    John L.
  • "Hi Dr Dendtler, Thank you so very much for fixing my eye. I can see clearly now…I can see all obstacles in my way! Love Vernell R"
    Vernell R.

Featured Articles

Read about interesting topics

Newsletter Signup

Sign up for more articles