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This information is provided by Provet for educational purposes only.

You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

Hypothyroidism is a common in dogs and there are numerous atypical presentations of the disease which should be sought during a clinical work-up 

Hypothyroidism is the commonest endocrine disorder in dogs. (It is not reported to occur in cats - except for congenital hypothyroidism which is extremely rare). Because of the importance of thyroid hormone on metabolic rate, virtually all organ systems are affected directly or indirectly by the hypothyroid state. The commonly reported clinical signs of severe hypothyroidism are :

  • Alopecia +/- pigmentation
  • Lethargy
  • Weight gain (NOT necessarily obesity)
  • Dullness
  • Dry, scaly skin
  • Intolerance to cold
  • Reduced fertility
  • Constipation
  • Decreased heart rate

Unusual  signs are :

  • Generalised weakness - slow stiff movements. This is most often due atrophy of type II muscle fibres. Affected dogs have high blood creatine kinase concentrations and bizarre high frequency discharges on electromyographic examination.
  • Neurological disorders including Central Nervous System and/or Peripheral Nervous System signs including : circling, dragging front feet, head tilt, impaired hearing, nystagmus. ** Feedback Requested. These are common clinical signs, and often a specific diagnosis is not reached. Provet would like to hear from YOU if you routinely screen for hypothyroidism when such cases are presented. Please contact . Thank YOU 
  • Atherosclerosis - although common in humans this condition is rare in dogs and cats. It is seen in dogs with hypothyroidism. As the vessel lumen gets narrower it reduces blood blood flow to vital organs. In theory this could predispose the animal to develop a true "stroke". Feedback request. Provet would like to hear from YOU if you have seen a case of atherosclerosis with/without hypothyroidism, associated with the typical human signs of "stroke" . Please contact Thank YOU.
  • Stunted growth (cretinism) can be a sign of hypothyroidism because thyroid hormones are essential for normal musculoskeletal development.
  • Lactation - unusual or prolonged lactation can occur in response to high prolactin concentrations in the blood, stimulated by excess thyrotropin-releasing hormone. Inappropriate lactation is not infrequently seen in older bitches and may be due to hypothyroidism. Feedback Request. Provet is conducting an on-line survey on this and would like to hear from you if you have confirmed hypothyroidism in such cases. Send the details to Thank YOU
  • Secondary endocrinopathies including hypoadrenocorticism, diabetes mellitus and hypoparathyroidism, hypogonadism may be concurrent with hypothyroidism ...due to a generalised autoimmune reaction. Let us know if you have seen a case at Thank YOU.

Clinical conditions which have been linked to hypothyroidism in the past but which have not been confirmed by TSH stimulation tests in all cases are :

  • Dilated cardiomyopathy in Doberman Pinschers (some cases confirmed)
  • Horner's Syndrome (with facial paralysis) - no cases to support link
  • Laryngeal paralysis (some cases confirmed)
  • Megaoesophagus - no cases to support link