Funding sources: This research received no grant from any funding agency in the public, commercial, or not-for-profit sectors.
THYROID SCINTIGRAPHY FINDINGS IN 2096 CATS WITH HYPERTHYROIDISM
Article first published online: 2 MAY 2014
© 2014 American College of Veterinary Radiology
Veterinary Radiology & Ultrasound
Volume 56, Issue 1, pages 84–95, January/February 2015
How to Cite
Peterson, M. E. and Broome, M. R. (2015), THYROID SCINTIGRAPHY FINDINGS IN 2096 CATS WITH HYPERTHYROIDISM. Veterinary Radiology & Ultrasound, 56: 84–95. doi: 10.1111/vru.12165
Previous presentations and abstracts: This study was presented as a research abstract at the 32rd Annual Veterinary Medical Forum of the American College of Veterinary Internal Medicine, New Orleans, LA in 2012.
- Issue published online: 15 JAN 2015
- Article first published online: 2 MAY 2014
- Manuscript Accepted: 6 MAR 2014
- Manuscript Received: 23 SEP 2013
Thyroid scintigraphy is currently the reference standard for diagnosing and staging cats with hyperthyroidism, but few studies describing the scintigraphic characteristics in a large number of cats have been reported. The objective of this study was to better characterize thyroid scintigraphy findings by evaluating 2096 consecutive cats with hyperthyroidism that were referred over a 3.5-year period. Of these cats, 2068 (98.7%) had a high thyroid-to-salivary ratio (>1.5), whereas 2014 (96.1%) were found to have a high thyroid-to-background ratio (>6.1). When the patterns of the cats’ thyroid disease were recorded, 665 (31.7%) had unilateral disease, 1060 (50.6%) had bilateral-asymmetric disease (two thyroid lobes unequal in size), 257 (12.3%) had bilateral-symmetric disease (both lobes similar in size), and 81 (3.9%) had multifocal disease (≥3 areas of increased radionuclide uptake). The number of areas of 99mTcO−4 uptake in the 2096 cats ranged from 1 to 6 (median, 2), located in the cervical area in 2057 (98.1%), thoracic inlet in 282 (13.5%), and in the thoracic cavity in 115 (5.5%). Ectopic thyroid tissue (e.g. lingual or mediastinal) was diagnosed in 81 (3.9%) cats, whereas thyroid carcinoma was suspected in 35 (1.7%) of the cats. The results of this study support conclusions that most hyperthyroid cats have unilateral or bilateral thyroid nodules, but that multifocal disease will develop in a few cats that have ectopic thyroid disease or thyroid carcinoma. Both ectopic thyroid disease and thyroid carcinoma are relatively uncommon in hyperthyroid cats, with a respective prevalence of ∼4% and ∼2% in this study.