What are the symptoms Hypothyroidism?

Most cases of hypothyroidism are caused by lymphocytic thyroiditis (autoimmune thyroiditis). Idiopathic (of no known cause) is another, rarer, cause of thyroid malfunction. Although lymphocytic thyroiditis is known to be hereditary, the cause of both types is unknown.

The most common symptoms include (%= approximate % of hypothyroid dogs that exhibit that symptom):

  • High blood cholesterol 80%
  • lethargy 70%
  • hair loss 65%
  • weight gain 60%
  • poor coat condition; often brittle, excessive shedding 60%
  • Anaemia 50%
  • skin conditions 25%+
  • irritability


What is Hypothyroidism?

Hypothyroidism is also known as underactive thyroid. It is a condition where the thyroid gland, which produces hormones,   Thyroxine (T4) and Triiodothyronine (T3),  is dysfunctional and not producing these hormones as required by the body. T4 and T3 are hormones that control the bodies metabolism.

Thyroid dysfunction including the most common, hypothyroidism, is a relatively common endocrine disease in dogs. The thyroid is a complex gland and results can be adversely affected by:

  • vaccination;
  • other drugs;
  • diet supplementation;
  • seasons;
  • other non thyroid related illness; and
  • general wellbeing.

Therefore,  issues concerning the thyroid are also considered to one of the most misdiagnosed.

Basenjis have a lower normal reference range to T4 and fT4 than most other breeds. A ground breaking study by the University of Sydney in the early 2000's found that the reference range in Basenjis, and some other sight hounds, can be much lower than the normal ranges accepted for other breeds. It is important that if thyroid dysfunction is considered by a vet that a full thyroid panel is done to include T4/fT4, cTSH as a minimum and its a good idea to have cholesterol checked as well as high cholesterol can be a symptom of thyroid issues. The ranges of T4 and cTSH are evaluated together rather than against their individual reference ranges. A Basenji with low T4 but with cTSH in the normal range and normal cholesterol would generally be considered to have normal thyroid. If the T4 is low and cTSH is getting toward the upper limit of normal and cholesterol is also high a further test in a couple of months would be advisable. A Basenji with low T4 and cTSH much higher than the accepted normal range with or without higher cholesterol would be considered as hypothyroid and medication may be required.

What is the Thyroid?

The thyroid is a gland that is located in the throat below the larynx. It's purpose is to produce hormones which control the rate of metabolism;  Thyroxine (T4) and Triiodothyronine (T3). It is stimulated into the production of T4 and T3 by Thyroid Stimulating Hormone (cTSH) which is produced by the pituitary gland.

Canine Thyroid