Clinical evaluation of thyroid function in racing pigeons (Columba livia domestica)

Reference values for basal thyroxine (T4) concentrations in racing pigeons are presented for use in clinical pathology. Values for basal plasma T4 concentrations in healthy racing pigeons over the four seasons were 6-35 nmol/litre. Significant differences were seen between seasons. To differentiate between primary hypothyroidism and other causes of lowered plasma T4 concentrations the optimum dose and sampling times for a TSH stimulation test in this species were determined. A convenient application of this test in the pigeon is to collect a blood sample at the end of a working day and then to administer 1 IU of TSH intramuscularly. The second blood sample is collected the following morning, about 16 hours later. In healthy pigeons T4 concentrations between 100 and 300 nmol/litre can be expected in the post-TSH sample representing a 3.5- to 15.3-fold increase above basal values.