Novel Echocardiographic Variables and Holter Monitor Findings in Healthy Mature Alpacas and Llamas

Abstract:

Background: Minimal reference data are available regarding echocardiographic variables in camelids.

Objectives: To expand reference information for echocardiographic variables and cardiac rhythm in healthy adult alpacas and llamas. Animals: 50 alpacas (7.9 ± 4.9 years; 157.6 ± 26.7 lbs) and 33 llamas (7.5 ± 5.2 years; 294.7 ± 43.6 lbs) of mixed sexes, owned by clients and the institution.

Methods: Prospective clinical study. All animals underwent comprehensive unsedated echocardiography; 15 alpacas and 11 llamas also had continuous ECG recording for 18-24 hours (Trillium Platinum Holter v4.66). Data presented as 95% CI.

Results: Left ventricular internal diameter (end diastole) in alpacas was 49.3-52.0 mm; llamas: 55.5-59.9 mm. Fractional shortening was 35.5–38.6% and 36.9–40.7% at mean heart rates of 55.9 ± 11.2 and 51.8 ± 9.0 bpm, for alpacas and llamas, respectively. Relative wall thickness was similar between species (0.38-0.44). Diameters (mm) of the left atrium, aortic sinus and pulmonary sinus from left parasternal long axis views at end diastole were 49.0-51.6, 32.4-34.5 and 26.4-28.5 for alpacas, compared to 63.7-67.8, 40.3-44.1 and 34.6-37.9 for llamas. Heart rates during holter monitoring ranged from 32-135 bpm (mean 52 ± 7) in alpacas and from 25-101 bpm (44 ± 6) in llamas. Extended periods of bradycardia were apparent in both species; documented rhythms included sinus arrythmia, sinus pauses, second degree atrioventricular block and atrial premature depolarizations. Sinus arrhythmia was very common and premature depolarizations sporadic. Conclusions and Clinical Importance: These data provide clinically practical new information regarding echocardiography variables and normal cardiac rhythms in camelids.