Hypothyroidism

Hypothyroidism is a generalized metabolic disease resulting from deficiency of the thyroid hormones levothyroxine (T4) and liothyronine (T3).

Canine hypothyroidism is usually primary, i.e. due to atrophy (or shrinkage) of the thyroid gland. In the majority of cases the atrophy is associated with inflammation and in the remainder it is non-inflammatory and as of yet unknown cause or Idiopathic.

SYMPTOMS

Clinical signs can include:-

  • Hair loss on the tail or flanks – NOT associated with scratching.
  • Dry scaly skin
  • Dull brittle hair
  • Lethargy
  • Weight gain
  • Reluctance to exercise
  • Neurological signs – facial paralysis, loss of balance or weakness

Initial diagnosis

Blood tests for biochemistry, electrolytes and haematology, thyroid hormone (T4) and thyroid stimulating hormone (TSH).

Treatment

This involves replacing the thyroid hormone that is not being produced by the body. Tablets are generally given every 12 hours and the medication will need to be continued for life.

After initiating treatment

After two weeks on therapy Thyroid hormone (T4) levels and Thyroid Stimulating hormone (TSH) are assessed. A blood sample is required and needs to be taken 4 to 6 hours after tablets are given (therefore it is advisable to give medication in the morning rather than the evening if on once daily dosing)

Blood samples will be taken every two weeks until optimum dose is identified.

Monitoring

Blood tests for biochemistry, electrolytes and haematology, thyroid hormone (T4) and thyroid stimulating hormone (TSH) - every six months.