Canine Hypothyroidism by Trish Parkin

What is canine hypothyroidism?

Hypothyroidism is a disorder of the thyroid gland – two small butterfly-shaped lobes located in the neck. This gland has a number of functions but is most well-known for regulating your dog’s metabolic rate. In hypothyroidism, the thyroid gland is underactive and unable to secrete enough thyroid hormone. This decreases your dog’s metabolism.

How does a dog get hypothyroidism?

Most cases of hypothyroidism stem from a dog’s own immune system attacking the tissues of the thyroid gland. This condition is called autoimmune thyroiditis. A dog’s system attempts to compensate for this secreting  initially more and more of the thyroid hormone but eventually the gland is unable to keep up with the attacks on its tissue, and the dog becomes hypothyroid and symptomatic. While there is a genetic predisposition for thyroid disorders, environmental factors such as pollutants and allergies probably play a role as well.

What are the symptoms of hypothyroidism?

  • Lethargic behavior such as a lack of interest in play, frequent napping and tiring out on long walks
  • Weight gain, sometimes without an apparent increase in appetite
  • Bacterial infections of the skin
  • Dry skin
  • Hair loss, especially on the trunk or tail (“rat’s tail”)
  • Discoloration or thickening of the skin where hair loss has occurred
  • Cold intolerance and seeking out warm places to lie down
  • Low heart rate
  • Chronic ear infections
  • Severe behavioral changes such as unprovoked aggression, head tilt, seizures, anxiety and/or compulsivity
  • Depression

Are there certain breeds that are more susceptible to hypothyroidism?

Most dogs that are affected by hypothyroidism fall into the mid to large size category. Many breeds are affected by this disease, including (but not limited to):

  • Golden Retrievers
  • Doberman Pinschers
  • Greyhounds
  • Irish setters
  • Dachshunds
  • Cocker Spaniels
  • Airedale Terriers

Hypothyroidism is rare in toy and miniature dogs.

How is hypothyroidism diagnosed?

Diagnosis begins with a full examination and taking a complete history. Your veterinarian will be looking for clinical signs of hypothyroidism during a thorough physical examination of your dog, and will ask questions about your dog’s health and behaviour. If hypothyroidism is suspected, a blood test will be ordered. There are a number of different methods for testing the thyroid gland. They involve some complicated terminology but it is important to understand the efficacy of these tests when discussing a diagnosis with your veterinarian:

  • Baseline T4 Test or Total T4 (TT4): This is the most common test. Dogs with failure of the thyroid gland will have a lower level of the T4 hormone. However, there are other conditions that can cause the T4 to decrease.  So if this test comes back positive for hypothyroidism your vet will recommend a Thyroid Profile which includes some of these tests:  TSH, Free T4 by RIA, Free T4 by ED and Baseline T3

How is hypothyroidism treated?

Hypothyroidism is treated with a daily dose of synthetic thyroid hormone called thyroxine (levothyroxine). Blood samples need to be drawn specified intervals to assess dosage effectiveness and to make any necessary adjustments.

What should I expect from the treatment?

Most symptoms of hypothyroidism clear up after treatment. With regular scheduled check-ups to ensure correct dosage, your dog should be mostly symptom-free for the rest of its life. Hypothyroid dogs that receive proper treatment have a normal life span and are able to maintain good health well into their golden years.

Chronic Care Program

NTVH has just launched a new program called the Chronic Care Program.  This no fee program has been set in place to benefit patients with chronic conditions and help pet owner’s mange these conditions more effectively.

Canine hypothyroidism is the first chronic disease that this program has launched.  All participating clients will receive a package outlining the disease as well as Loyalty Card.  The loyalty card provides you discounts at various places that we have set-up throughout the community.  The other great thing about this program is that for every Chronic Care Exam preformed $5.00 is donated to the Oscar Fund.  The Oscar Fund is a charitable program that NTVH has set up to help animals in need that would otherwise not receive care.  Check it out on our website.