Thoracic radiography of healthy captive male and female Squirrel monkey (Saimiri spp.)

The effect of different body positions on the cardiothoracic ratios obtained by chest radiography in Japanese macaques (Macaca fuscata) AND RHESUS MACAQUES (Macaca mulatta)

BACKGROUND

Although some studies have reported cardiac diseases in macaques, an adequate screening method for cardiac enlargement has not yet been established. This study aimed to evaluate the positioning of macaques for radiographs and establish reference intervals for the cardiothoracic ratio (CTR).

MATERIALS AND METHODS

We developed a device for chest radiography in the sitting position and performed chest radiography in 50 Japanese and 48 rhesus macaques to evaluate the CTR and chest cavity size.

RESULTS

In Japanese and rhesus macaques, the thorax height was significantly larger, the heart width was significantly smaller, and the mean CTR was significantly smaller in the sitting position than in the prone position. The reference intervals for CTR in the sitting position were 51.6 ± 4.6% and 52.2 ± 5.1% in Japanese and rhesus macaques, respectively.

CONCLUSION

Thoracic radiographic images obtained in a sitting position resulted in a smaller CTR and a larger thorax height, which could be useful for detecting pulmonary and cardiac abnormalities.

THORACIC RADIOGRAPHY AND TRANSTHORACIC ECHOCARDIOGRAPHY IN CLINICALLY HEALTHY RING-TAILED LEMURS (LEMUR CATTA)

Cardiac disease has been recognized as a major cause of death in captive nonhuman primates, which necessitates diagnostic (imaging) techniques to screen for and diagnose preclinical and clinical stages of possible cardiac conditions. Echocardiography is currently the most commonly used diagnostic tool for evaluation of cardiac anatomy and function. Complete with thoracic radiography and blood levels of two cardiac biomarkers, N-terminal probrain natriuretic peptide (NT-proBNP) and cardiac troponin T (cTnT), it gives an extensive examination of the cardiorespiratory system. The purpose of this cross-sectional cohort study is to describe normal thoracic anatomy using thoracic radiography, and to provide normal values for echocardiographic measurements in 20 ring-tailed lemurs (Lemur catta). Additionally, cardiac biomarkers were determined. Three radiographic projections of the thoracic cavity and a complete transthoracic echocardiography were performed in 20 clinically healthy ring-tailed lemurs during their annual health examinations. Similar standard right parasternal and left apical echocardiographic images were obtained as described in dogs and cats and normal values for routine two-dimensional (2D-), time-motion (M-) and Doppler mode measurements were generated. Furthermore, a noninvasive smartphone base ECG recording and blood concentrations of cardiac biomarkers were obtained. Other radiographic measurements are provided for the skeletal and respiratory systems such as the trachea to inlet ratio and tracheal inclination. Knowledge of the normal radiographic thoracic and echocardiographic anatomy and function are fundamental for the diagnosis and follow-up of cardiac disease in affected individuals and for species screening, and will be of added value in future research in and conservation of this endangered species.

Transthoracic echocardiography and cardiac biomarkers in healthy captive male and female squirrel monkeys (Saimiri spp.)

Background

Echocardiography is the most frequently used non -invasive diagnostic tool to evaluate cardiac anatomy and function in domestic species but increasingly also in non -domestic species, especially since cardiac disease is being recognized as an important cause of death in captive primates. The purpose of this cross -sectional study was to investigate the feasibility of transthoracic echocardiography in healthy squirrel monkeys as well as to provide species specific normal values for standard echocardiographic measurements. A secondary aim was to determine plasma and serum levels of the cardiac biomarkers, N -terminal pro -brain natriuretic peptide (NT -proBNP) and cardiac troponin T (cTnT). Furthermore, a commercial, non -invasive, smartphone -based ECG (AliveCor Vet TM) monitoring device was used to evaluate the heart rate and rhythm and to diagnose possible arrhythmias.

Results

In this study, transthoracic echocardiography of 14 squirrel monkeys was performed in right and left lateral recumbency. Similar standard right parasternal and left apical images were obtained as in dogs and cats and normal values for routine two -dimensional, time motion mode and Doppler mode measurements were generated. Thirteen animals were considered healthy and one squirrel monkey was identified with significant aortic dilation and regurgitation and consequently values obtained from this animal were not used when species specific normal values were calculated. NT -ProBNP and cTnT concentrations were available for 7 of the 13 healthy monkeys with NT -proBNP concentrations below detection limit in all animals and a mean cTnT concentration of 0.049 ng/mL. Electrocardiography was performed in all squirrel monkeys. The mean heart rate was 172 bpm. Frequent supraventricular premature beats were diagnosed in the squirrel monkey suffering from significant aortic dilation and regurgitation.

Conclusion

This study presents echocardiographic normal values and additional cardiovascular data in anaesthetised Saimiri monkeys, fundamental from both the perspective of zoo animal health care as well as scientific research, since the squirrel monkey is often used as an animal model for human disease.

Vertebral Heart Score in Rhesus Macaques (Macaca mulatta): Generating Normal Reference Intervals and Assessing its Validity for Identifying Cardiac Disease

Vertebral heart scoring (VHS) is a semiquantitative method to assess the presence and severity of cardiomegaly by using thoracic radiographs. VHS in rhesus macaques (Macaca mulatta) has not been validated or used routinely in the clinical or research setting. We hypothesized that rhesus macaques with cardiac disease diagnosed by using echocardiography would have higher VHS than animals without cardiac disease. A total of 150 rhesus macaques were enrolled in this study. All animals underwent echocardiography and thoracic radiography (right lateral [RL], dorsoventral [DV], and ventrodorsal [VD] views).According to echocardiography, 121 rhesus macaques had no cardiac disease and were used to establish reference intervals for VHS. The remaining 29 macaques had hypertrophic cardiomyopathy (n = 20) or other cardiac disease (n = 9). Results showed that VHS of RL and VD views were significantly higher in macaques with any of the identified cardiac diseases and in the cardiac disease group that excluded hypertrophic cardiomyopathy. VHS of animals with HCM was not significantly different than that of control animals. In the RL view, VHS was moderately accurate for predicting the presence of cardiac disease, with an AUC of 0.71 and an optimal cut-off value of 10.25 (sensitivity: 62%, specificity: 77%). In the VD view, VHS was a mildly accurate test for cardiac disease, with an AUC of 0.654 and an optimal cut-off value of 10.65 (sensitivity, 66%;specificity, 63%). Study results indicated that VHS could be a useful screening tool for clinically identifying rhesus macaques with cardiac disease. However, VHS is unlikely to replace echocardiographic examination for determining the presence, type,and severity of cardiac disease in this species.