SUMMARYElectrocardiographic reference values and configurations were established in apparently healthy African grey (Psittacus erithacus; n=45) and Amazon (Amazona spp.; n = 37) parrots, using standard limb leads. In 31 of the African grey parrots and 32 of the Amazon parrots electrocardiograms were made during isoflurane-anaesthesia. Significant differences between anaesthetized and unanaesthetized birds were found only for the median heart rate and QTinterval (P<0.05). Significant differences between the two genera were found for the duration of the P-and T-waves, the voltage of the T-wave and for the mean electrical axis.Sinus arrhythmias and ventricular premature beats were present in 5 to 10% of the tracings.

Thyroidal ""TcO~ (pertechnetate) uptake percentages were determined in unanesthetized euthyroid (n = 13) and hyperthyroid (n = 18) cats. Maximal uptakes were observed 60 minutes after IV injection of the radionuclide and ranged from 0.3 to 3.9% of the dose in euthyroid cats (median 2.23%) and from 5.2% to 23.9% of the dose in hyperthyroid cats (median 14.8%) (P < .05). There were no overlaps in pertechnetate uptake percentages during any lthough not used as a primary diagnostic test, the in A vivo use of a radionuclide in a thyroidal uptake study may be a useful adjunct in the diagnosis of feline hyperthyroidism.1,2 Pertechnetate or 1231 are preferred over I3'I for thyroid imaging because the latter has several disadvantages (eg, long half-life of 8 days, emission of beta particles, relatively high energetic gamma radiation). Pertechnetate is used commonly in small animals because of its ready availability and because prior administration of antithyroid drugs does not interfere with thyroid imaging. The configuration of the pertechnetate ion mimics that of iodide to such a degree that it is trapped by the thyroidal iodide-concentrating mechanism but is not incorporated into the organic form, and therefore, not retained in the thyroid gland. Thus, 99mT~O; uptake reflects the trapping mechanism of the gland. Some other epithelial structures (eg, salivary glands) can also concentrate 99"TcO; without organic binding.The quantitative aspects of thyroidal 13'1 uptake have been described in both hyperthyroid and euthyroid Dynamic studies with 99"TcO; are considered valuable in human patients with suspected hyperthyroidism,' but quantitative aspects of 99mTcO; uptake have been studied less extensively in cats. Mooney and others described the quantitative thyroidal uptake of 99"T~0; 20 minutes after injection of the radionuclide.6 Beck and others calculated ratios for uptake in thyroid and salivary glands.' The present study was designed to determine the optimal time for thyroid imaging when using 99mTcO; and to obtain values for uptake percentages in euthyroid and hyperthyroid cats. Materials and Methods cutsThree male (2 castrated) and 3 female (2 spayed) cats from the Central Animal Laboratory Unit of the University of Utrecht ranging in ages from 1 to 5 years (median 3 years) served as controls; they were fed a commercial cat food (Hopefarms complete dry cat food; Hopefarms BV, Woerden, The Netherlands), combined with Rodi heart (Rodi BV, Opmeer, The Netherlands). Other control cats (4 males and 3 females, all neutered) were privately owned, with ages ranging from 2 to 17 years (median, 12 years). They were fed various brands of commercial cat foods. All the control cats were healthy, and routine biochemical evaluation for kidney and liver diseases revealed no abnormalities. In all of the control cats, plasma thyroxine concentration was below the upper limit of the reference range (46 n m~l / L ) .~.~ There were 7 male and 8 female (all neutered) hyperthyroid cat$ ranging in age from 1 I to I5 years (median, 13 years...