TDK conference 2018

The ultrasonography is a sensitive and specific method to detect adrenal gland size. The most reliable indicator of the adrenal glands’ sizes are maximum diameters of caudal pole’s (later thickness) measurments. Among dogs the upper limit of normal value were 7,4 mm according to previous concordant literature. There are contradictory results in previous literature about correlation between bodyweight and the thickness of adrenal glands. It may be hypothesized, if adrenal gland thickness has some correlation with the bodyweight, we could diagnose a bigger adrenal gland, than normal at small-breed dogs. Therefore as a result of this diagnostic problem, during the last few years one study suggests a new cut-off value for dogs under 10 kg to be 6 mm.

Our intention is to examine adrenal glands’ thickness and normal value dependency from bodyweight under 10 kg.

We made our retrospective study on 67 dogs, which were examined in the endocrinology clinic of Állatorvostudományi Egyetem from 2008 to 2017. 31 of them were normal and have no adrenal gland sickness. Dogs bodyweight extend from 3,0 to 42,0 kg. We examined with statistic method the whole normal group (n=31), the dogs, which were under 10 kg (n=17) and the dogs, which were under 10 kg compair with dogs, which were over 10 kg and compare with dogs, which have Cushing disease. When we examined the whole normal group (n=31), the adrenal gland size correlates with the bodyweight, while adrenal gland size of dogs under 10 kg we cannot detect these kind of correlation. We found significant difference between adrenal glands sizes of dogs under and upper 10 kg groups. In our study in the group of small-breed dog’s average value of the maximum diameter at the left adrenal gland’s caudal pole were 4,5 mm with scatter +/-0,7 mm (n=17), at the rights one’s average value were 4,7 mm with scatter +/-0,8 mm (n=15). If we assume normal distribution, the normal value of the left adrenal gland’s size is 3,1-5,9 mm and at the right one this is 3,1-6,3 mm (95% confidence interval). We set the cut-off value at dogs under 10 kg to be 5,5 mm after comparing the normal group with the group, on which Cushing disease was diagnosed. With this cut-off value we get 82% sensivity and 95% specifity at the left adrenal gland and 76% sensivity and 88% specifity at the right using ultrasonography in diagnosing Cushing disease. These sensivity-specifity values are similar to literatures proving our diagnostic method.

In conclusion we detected that the thickness of adrenal glands correlate with bodyweight from 1 to 42 kg. Under 10 kg (n=17) we can not detect this kind of correlation and this group has significantly smaller adrenal gland size, than the previous recommended 7,4 mm. We set the cut-off value at normal dogs under 10 kg to be 5,5 mm. This value is distinguishable from the 7,4 mm which is used at larger dogs. These findings are similar to the recent studies’ results and give an exemplary diagnostic criteria.