What is hypothyroidism?

The most common hormone problem encountered in dogs is hypothyroidism.  It results when the thyroid gland does not secrete an adequate quantity of thyroid hormone called thyroxine.  Many internals organs are affected, and the resulting problem depends on which organs are most affected.

How does a dog get hypothyroidism?

Most cases of hypothyroidism stem from the dog’s own immune system attacking the tissue of the thyroid gland.  This condition is called autoimmune thyroiditis.  The dog’s own system attempts to compensate for this at first by secreting 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, tiring on long walks

• Weight gain, sometimes without an apparent gain 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/seeking out warm place to lie down

• Slow heart rate

• Chronic ear infections

• Severe behavioral changes such as unprovoked aggression, head tilt, seizures, anxiety and/or compulsivity

• Depression

How is hypothyroidism treated?

Diagnosis of this disease is done by a series of blood tests.  These tests are fairly common and can be conducted by your veterinarian.  Hypothyroidism is treated with a daily dose of synthetic thyroid hormone called thyroxine (levothyroxine).  Blood samples will need to be drawn periodically to assess the effectiveness of the dosage and make any adjustments necessary.

What should I expect from the treatment?

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

 

If you would like further information or would like to have your dog tested for hypothyroidism, contact your veterinarian.