Ultrasonographic adrenal gland findings in healthy semi-captive cheetahs (Acinonyx jubatus).

Cheetahs in captivity are believed to suffer from stress predisposing them to poor health. To date fecal glucocorticoids have been used as a non-invasive indicator of chronic stress. This study examines, the feasibility of transabdominal adrenal gland ultrasonography in cheetahs and determined normal adrenal measurements that can potentially be used as a more reliable indicator of chronic stress and/or adrenal function. Thirty-three adult cheetahs, aged between 2 and 13 years, accommodated in large off-display camps were examined over 9 days under general anesthesia. The adrenals were readily identified, with the right adrenal being more difficult to find and measure than the left, and were smaller than those expected in similar sized dogs. The left adrenal was shorter and slightly more oval shaped than the right with a length and cranial pole width at a 95% prediction interval of 16.3-22.4 and 4.1-8.7 mm. The same measurements for the right adrenal were 16.8-26.2 and 3.4-10.8 mm, respectively. Corticomedullary ratios were larger for the left adrenal. When corrected for body size, females had significantly longer and greater left adrenal corticomedullary ratios than males. Adrenal measurements did not correlate with left renal length, body size measurements, or enclosure size. Measurements that increased with age included the cortical and total adrenal widths. Adrenal ultrasonography offers potential benefits in assessment of individual cheetah adrenal pathology or the evaluation of stress induced adrenomegally especially in combination with other evaluations such as non-invasive fecal glucocorticoid analyses. Zoo Biol. 35:260-268, 2016. © 2016 Wiley Periodicals, Inc.