UC Davis

The goal of this study was to generate reference intervals for echocardiographic variables in a population of clinically normalgeriatric rhesus macaques (Macaca mulatta). To do this, we studied 51 animals (age, 18-29 y; weight, 5.24-17.04 kg). Thenormal values for cardiac indices, including geometry and systolic and diastolic function, were determined by 2D, M-mode,spectral Doppler, and tissue Doppler echocardiography under ketamine hydrochloride sedation. Statistical correlations betweenthe echocardiographic parameters and age, body weight, sex, and heart rate were investigated. All echocardiographicindices were acquired, and their reference intervals were established. Multiple weak to strong correlations emerged betweenvariables and echocardiographic parameters, but no moderate or strong correlations between body weight or sex and theseparameters were noted. Of the 51 geriatric rhesus macaques evaluated, 36 (71%) fulfilled the criteria for diastolic dysfunction. Valve regurgitation, especially tricuspid regurgitation (43%), and aortic regurgitation (51%) also were common in geriatric rhesus macaques. Although these findings merit follow-up, they are unlikely to have clinical significance given their prevalence in these apparently healthy animals.