The objective of this project was to determine radiographic vertebral heart sizes and electrocardiographic (ECG) and echocardiographic measurements in healthy anesthetized maned wolves (Chrysocyon brachyurus). The wolves, housed at the White Oak Conservation and Smithsonian National Zoo Conservation and Research Centers, were being anesthetized for annual examinations. Cardiac auscultation, thoracic radiographs, a standard 6-lead ECG, and echocardiography were performed on the wolves while they were under general anesthesia. Thirteen maned wolves were evaluated: five males and eight females. Mean age was 6.4 /- 4.4 years (range, 2-13 years). Mean weight was 26 /- 2.95 kg (range, 22-32 kg). Low-grade systolic murmurs were auscultated in three of 13 maned wolves. Evaluation of ECGs revealed a sinus rhythm, with a QRS morphology, and mean electrical axis similar to domestic canines. Radiographic evaluation revealed a mean vertebral heart size of 8.27 /- 0.48 (range, 7.9-8.6). In addition, the cardiac silhouette was seen to elongate, with an increase in sternal contact in older wolves. Echocardiography showed that mitral valve degenerative changes and insufficiency is likely common in older wolves. Visualization of physiologic regurgitation across the mitral and pulmonary valves was common in wolves of all ages. Left ventricular measurements were similar to those reported for healthy dogs, and several variables correlated well with body weight. Two wolves were found to have one to three heartworms in the right pulmonary artery, and degenerative mitral valve disease was determined in maned wolves older than 6 years of age. All of the wolves in this study were on heartworm preventative and tested negative for heartworm antigen at their annual examinations. The results of this study provide reference information for use in the cardiac evaluation of anesthetized maned wolves.