Simpson's method of discs in Salukis and Whippets: Echocardiographic reference intervals for end-diastolic and end-systolic left ventricular volumes.

BACKGROUND Sighthound breeds are known to have different cardiac sizes and dimensions from other breeds; therefore, breed-specific references are required to avoid misinterpretation of echocardiographic findings. End-diastolic volume (EDV) and end-systolic volume (ESV) reference intervals derived from Simpson's method of discs (SMOD) do not exist for Salukis or Whippets. OBJECTIVES To establish EDV and ESV reference intervals for SMOD in Salukis and Whippets. ANIMALS 110 Salukis and 119 Whippets. METHODS Reference intervals for SMOD with and without normalization to body surface area (BSA) were established using the right parasternal and left apical views in 93 healthy Salukis and 82 healthy Whippets. Volumes were compared between both echocardiographic views, genders, and racing and show pedigree dogs. The 90% reference intervals were calculated using the robust method. RESULTS Agreement between right-sided and left-sided echocardiographic views was good. Reference intervals indexed to body surface area (BSA) for Whippets were 59-109 mL/m² for end-diastolic volume index and 18-53 mL/m² for end-systolic volume index. Corresponding values for Salukis were 68-126 mL/m² for end-diastolic volume index and 27-64 mL/m² for end-systolic volume index. There were no indexed volume differences between male and female or racing and show pedigree dogs in both breeds. The non-normalized volumes significantly differed between genders. CONCLUSIONS AND CLINICAL IMPORTANCE Whippets and Salukis had larger systolic and diastolic left ventricular volumes compared with other breeds. This study provided echocardiographic reference intervals for SMOD-derived left ventricular volumes for these athletic breeds.