Cardiac Evaluation of Clinically Healthy Captive Maned Wolves (Chrysocyon brachyurus)

Abstract

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.

Electrocardiographic exam in female spotted pacas (Cuniculus paca)

“…The PR and QT intervals are considered inversely proportional to heart rate (Tilley 1992) and may be elevated in anesthetized animals as observed by Szabuniewicz et al (1978) in capybaras, due to the positive Chrono-tropic effect of dissociative anesthetics described by Souza et al (2002) in dogs. The QRS complex duration values obtained in this study were similar to normal values of Brazilian agouti, capybaras, cheetahs, leopards and maned wolves (Szabuniew et al 1978, Schumacher et al 2003, Estrada et al 2009, Oda et al 2009, Diniz et al 2013) and higher than those reported in small rodents (Szabuniew et al 1971, Dudás-Györki et al 2011) and dogs (Tilley 1992). Although the variation in these values may not be correlated with size or heart rate in these animals, the value obtained is considered normal when compared with other species.…”

“…The P wave duration, PR, and QT intervals in pacas under chemical restraint were similar to that reported for capybaras (Szabuniewicz et al 1978) and other wild mammals using a similar restraint protocol (Schumacher et al 2003, Estrada et al 2009, Oda et al 2009), but were slightly larger than in Brazilian agouti, rabbits, ferrets and dogs under physical restraint (Szabuniew et al 1971, Tilley & Goodwin 2002, Dudás Györki et al 2011, Diniz et al 2013). Nevertheless, the P wave amplitude was similar to that found in non-anesthetized ferrets, Brazilian agouti and chemical restrained cheetahs (Schumacher et al 2003, Dudás-Györki et al 2011, Diniz et al 2013).…”

“…Heart rate obtained in the studied pacas was similar to described in cats, dogs, maned wolves, capybaras and cheetahs (Szabuniew et al 1978, Tilley 1992, Martin 2002, Schumacher et al 2003, Estrada et al 2009) higher than in Leopards (Oda et al 2009) and lower than in brazilian agouti (Diniz et al 2013). Although the capybara and brazilian agouti are phylogenetically closest to the paca (Ávila et al 2010), the heart rate of these species has a moderate variation.…”

“…The ECG tracing characteristics of spotted pacas in DII lead was similar to described for brazilian agouti, capybara, dogs, cats, ferrets, leopards, maned wolves, cheetahs and capuchin monkey (Szabuniewicz et al 1978, Martin 2002, Tilley & Goodwin 2002, Schumacher et al 2003, Estrada et al 2009, Oda et al 2009, Dudás Györki et al 2011, Larsson et al 2012, Diniz et al 2013, this ECG configuration indicate that the force of ventricular depolarisation spreaded principally to caudal and left side in front plane, due to positive R wave in DI, DII, DII and aVF, negative in aVR and small and variable in aVL leads, similar to described in ferrets (Dudás Györki et al 2011). Due to the DII lead characteristics this is considered the most widely used derivation for the rhythm, frequency, configuration, amplitude, and duration, cardiac waves analysis (Hurst & Meyerbur 1968), for this reason this derivation was presented as standard.…”

“…However, reference values have not been established for many of the wild species and the lack of information in the literature limits the standardization for the cardiac function studies, capable to indicate cardiovascular changes in these species (Stępien 1999, Gardne et al 2007, Estrada et al 2009). …”