Left atrial size in healthy Cavalier King Charles spaniels: a comparison to dogs of other breeds and previously published reference intervals

Abstract

Introduction: Recently, investigators have suggested that Cavalier King Charles spaniels have smaller left atrial-to-aortic ratios (LA:Aos) than other breeds.

Animals, materials and methods: This study comprised apparently healthy adult Cavalier King Charles spaniels (n = 218) and apparently healthy adult dogs of other breeds (n = 379), imaged by the same observers, for inclusion in the Osservatorio Veterinario Italiano Cardiopatie. Left atrial and aortic measurements, obtained from two-dimensional images at the closing of the aortic valve, and left ventricular internal dimensions in diastole, obtained from M-mode images, were both obtained from the right parasternal short-axis view. Furthermore, left atrial and aortic measurements were indexed allometrically and compared to data obtained by the same observers. Measurements obtained by multiple observers were compared for systematic bias. Reference limits were created for the LA:Ao and normalized left ventricular diastolic dimensions.

Results: Reference limits agreed with previously published limits for other dogs, with the upper reference limit for Cavalier King Charles spaniels approximating 1.6. Cavalier King Charles spaniels had allometrically indexed left atrial and aortic measurements that were not smaller than those in other dogs.

Study limitations: This is a retrospective study with multiple independent observers, not specifically instructed to measure the LA:Ao.

Conclusions: Cavalier King Charles spaniels have an LA:Ao not smaller than other breeds. Furthermore, the left atrial linear dimension obtained in the right parasternal short-axis view and normalized to bodyweight does not appear to be smaller. Consequently, current generic reference intervals for left atrial dimensions apply to Cavalier King Charles spaniels.

Keywords: Canine; Cardiac enlargement; Cardiac mensuration; Cardiomegaly; Echocardiography.