Quantitative 99mTc-pertechnetate thyroid scintigraphy in normal beagles

This study was done to investigate the validity of published canine thyroid/salivary (T/S) ratios of approximately 1 in normal dogs and to determine thyroid uptake of 99mTc-pertechnetate (pertechnetate) measured as percent uptake of injected dose. These parameters were evaluated in 13 Beagle dogs over a 4 hour period. Mean +/- standard deviation (SD) and median T/S ratios of 1.2 +/- 0.3 and 1.1 were essentially the same at twenty minutes and 1 hour. T/S values ranged from 0.9 to 2.2 at 20 minutes and from 0.8 to 2.4 at 1 hour. T/S ratio values progressively declined over the subsequent time intervals with mean +/- SD and median values of 0.6 +/- 0.2 and 0.6, respectively, measured at 4 hours. The mean +/- SD maximum percent dose uptake of pertechnetate within the thyroid gland was 0.55% +/- 0.15% with a range of 0.28% to 0.90%. The mean +/- SD time interval from injection of pertechnetate to maximum uptake within the thyroid gland was 160 +/- 55 minutes with a range 31-240 minutes. The data derived from this study of normal dogs may be useful in the evaluation of dogs with thyroidal diseases including hypothyroidism.