The breed-specific vertebral heart score and vertebral left atrial size in toy breed dogs

Vertebral heart score (VHS) and vertebral left atrial size (VLAS) are the objective measures of cardiac and left atrial sizes on thoracic radiographs in dogs. Previous studies have demonstrated that the normal VHS reference ranges can vary among breeds. This retrospective study aimed to evaluate the VHS and VLAS of healthy Maltese, Pomeranian, and Toy Poodle dogs, which were predisposed to cardiac disease. Fifty Maltese, 47 Pomeranian, and 45 Toy Poodles were enrolled. The VHS of Maltese, Pomeranian and Toy Poodles was 9.69 ± 0.51, 10.69 ± 0.62, and 9.94 ± 0.60, respectively. The VHS of Pomeranian and Toy Poodles were significantly higher than the canine reference value of 9.7 vertebrae. The VLAS of Maltese, Pomeranian and Toy Poodles was 2.03 ± 0.17, 2.17 ± 0.26, and 2.02 ± 0.15, respectively. Compared to the reference value of 1.9 vertebrae, the VLAS of Maltese, Pomeranian and Toy Poodles was significantly higher. The VHS and VLAS of Pomeranians were significantly higher than those of Maltese and Toy Poodles. The cardiomegaly or left heart enlargement could be overdiagnosed in healthy Maltese, Pomeranian and Toy Poodles, especially Pomeranians, therefore, the VHS and VLAS values in this study could be used as references.