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Development of an experimental model of hypothyroidism in cockatiels (Nymphicus hollandicus)

1994; American Veterinary Medical Association; Volume: 55; Issue: 3 Linguagem: Inglês

10.2460/ajvr.1994.55.03.399

1943-5681

Craig A. Harms, James J. Hoskinson, David S. Bruyette, James W. Carpenter, John C. Galland, Jobna K. Veatch, Sandra C. Wilson, Jeffrey G. Baier,

Bird parasitology and diseases

Summary Hypothyroidism is 2 possible predisposing factor in a number of disorders of companion psittacine birds. We developed and validated a thyroid-stimulating hormone ( tsh ) response testing protocol for cockatiels ( Nymphicus hollandicus ), using 0.1 IU of tsh /bird given IM, with blood sample collection at 0 and 6 hours after tsh , and a commercial radioimmunoassay for thyroxine (T 4 ). This protocol was used to document a seasonal sex difference in stimulated T 4 values— females responded with higher T 4 values than those in males in summer—and a stress-induced depression of baseline T 4 values was detected in a group of cockatiels with normal tsh response. An experimental model for mature-onset hypothyroidism in cockatiels was created by radiothyroidectomizing cockatiels with 3.7 MBq (100 μCi) of 131 I/bird given IV. Induction of the hypothyroid state was confirmed by baseline T 4 concentration, tsh response test results, thyroid pertechnetate scintigraphy, and gross and microscopic examinations. Classical signs of hypothyroidism (eg, hypercholesterolemia, obesity, poor feathering) were lacking or mild at 48 days after thyroid ablation.