Diagnosis and Long-term Treatment of Suspected Congenital Hypothyroidism in a Pigeon ().

Abstract

An approximately 6-month-old domestic pigeon () was presented for lethargy and an inability to perform its first molt. The pigeon was obese, had anatomical characteristics of a chick, including cere and plumage, and had a ventral coelomic soft tissue mass. Initial blood work was unremarkable. A computed tomographic scan confirmed excessive fat deposition in the coelom and a mass adherent to the liver. A fine-needle aspirate of the mass indicated fat accumulation. A thyroid-stimulating hormone (TSH) test was planned for this pigeon and 3 presumed euthyroid pigeons. Each pigeon was administered 80 &#xb5;g (&#x223c;230 &#xb5;g/kg) of recombinant human TSH. Blood was drawn at time 0 and 3 and 6 hours after administration of recombinant human TSH. Plasma total thyroxine (TT) was measured in duplicate with an in-house analyzer and a reference laboratory. After recombinant human TSH administration, healthy pigeons showed a 4- to 21-fold increase in TT, whereas the hypothyroid pigeon had all values <0.12 &#xb5;g/dL. The pigeon was prescribed 20 &#xb5;g of compounded levothyroxine twice daily. In the following months, the pigeon molted and developed adult features. The ventral coelomic soft tissue mass disappeared and repeated computed tomography scans showed a decreased amount of body fat and a reduction in the size of the coelomic mass. Levothyroxine was further adjusted multiple times according to additional TTtesting to a dose of 2.5 &#xb5;g once daily. The pigeon has been under treatment with levothyroxine for more than 2 years. Here we present the first reported case of confirmed hypothyroidism in a pigeon. Diagnosis with a TSH stimulation test was unequivocal, even when only considering the results of the in-house analyzer. Levothyroxine treatment resolved clinical signs and could be titrated to an appropriate dose.