QUANTITATIVE THYROID SCINTIGRAPHY IN GREYHOUNDS SUSPECTED OF PRIMARY HYPOTHYROIDISM
Article first published online: 26 FEB 2009
© 2009 American College of Veterinary Radiology
Veterinary Radiology & Ultrasound
Volume 50, Issue 2, pages 224–229, March/April 2009
How to Cite
PINILLA, M., SHIEL, R. E., BRENNAN, S. F., McALLISTER, H. and MOONEY, C. T. (2009), QUANTITATIVE THYROID SCINTIGRAPHY IN GREYHOUNDS SUSPECTED OF PRIMARY HYPOTHYROIDISM. Veterinary Radiology & Ultrasound, 50: 224–229. doi: 10.1111/j.1740-8261.2009.01521.x
- Issue published online: 26 FEB 2009
- Article first published online: 26 FEB 2009
- Received May 29, 2008; accepted for publication September 15, 2008.
The existence of hypothyroidism in greyhounds remains controversial and its investigation is complicated by the low circulating thyroid hormone concentrations typically found in healthy dogs of this breed. Quantitative measurement of thyroidal technetium-99m pertechnetate (99mTcO4−) uptake is known to be useful in assessing thyroid function in other breeds. The aim of this study was to evaluate thyroid scintigraphy as a method of assessing thyroid function in greyhounds suspected of primary hypothyroidism. Twenty greyhounds (eight females, 12 males) were studied. Thirteen had bald thigh syndrome and seven poor performance and low total T4. Total T4 concentrations were decreased in 18 (90%), and free T4 in two (10%) dogs. All canine thyroid stimulating hormone concentrations were within the reference interval. Thyroidal 99mTcO4− uptake values (mean ± SD, 0.76 ± 0.26%) were within the reference limits published for euthyroid dogs (0.39–1.86%) making hypothyroidism highly unlikely. There were no significant differences (P<0.05) when comparing data between dogs with bald thigh syndrome (13 dogs) and the remaining dogs (seven dogs). Seventeen (85%) dogs had higher uptake in the left thyroid gland than in the right that might reflect an anatomic feature of the greyhound breed. Calculation of percent thyroidal uptake of 99mTcO4− is more accurate than thyroid:salivary gland ratios because of high variability in salivary gland uptake. Percent thyroidal uptake of 99mTcO4− should be used when assessing thyroid function scintigraphically in the greyhound breed.