Congenital hypothyroidism in a kitten resulting in decreased IGF-I concentration and abnormal liver function tests

Abstract

A 7-month-old male kitten was presented with chronic constipation and retarded growth. Clinical examination revealed disproportional dwarfism with mild skeletal abnormalities and a palpable thyroid gland. The presumptive diagnosis of congenital hypothyroidism was confirmed by low serum total thyroxine (tT(4)) concentration prior to and after the administration of thyroid stimulation hormone (TSH), increased endogenous TSH concentration and abnormal thyroid scintigraphic scan. The kitten had abnormal liver function tests and decreased insulin-like growth factor 1 (IGF-1) concentration, both of which returned to normal in correspondence with an improvement of the clinical signs after 6 weeks of thyroxine therapy. Congenital hypothyroidism is a rare disease that may present with considerable variation in clinical manifestation. In cases in which clinical signs are ambiguous, disorders such as portosystemic shunt and hyposomatotropism have to be taken into account as differential diagnosis. As hypothyroidism may be associated with abnormal liver function tests and low IGF-1 concentrations, test results have to be interpreted carefully.

Fig 1

(a) The 7-month-old Siamese mixed breed kitten at the time of presentation. The kitten has infantile appearance, the head appears broad in comparison to the rest of the body. Scanty hair coat with crusts on the ear margins and a ‘rat tail’ are also present. (b) Same kitten with one of his normal-sized littermates. It has about the third of the size of his littermate.

Fig 2

The laterolateral abdominal radiograph shows mild scalloping of the vertebral bodies, mildly widened vertebral physes and a prominent concave shape of the vertebral end plates. Large amounts of faeces are present in the colon.

Fig 3

Same cat at the age of 3 years.