Abstract: Objective To observe and measure the main anatomical structure of canine hearts cavity,and to accumulate data for the study of comparative zootomy. Methods The hearts from fourty-five dogs fixed with 10% formaldehyde for one week were dissected, then were observed and measuredrelative datas of the mitral complex tricuspid complex tricuspid valve ring aortic orifice pulmonary veins in front of and behind vena cava coronary sinus and fossa oval is dealed with statistics then analyzed the datas and compared with human heart. Results 1. The left ventricle of canine heart was a cone. It was divided into the gateway of left ventriclc and outlet of left ventricle. The main structure of the gateway was mitral complex, which was composed of the mitral ring and valve chordae tendinease and papillary muscles. The length of mitral ring was 49.16 ± 10.00mm. The average number of chordae tendineass was 16.72 ± 2.79. The main structures of the outlet of left ventricle were aortic valve aortic sinus and aortic orifice. The length of aortic orifice was 34.55 ± 8.00 mm. 2. The main anatomical structures of the right ventricle in canine were made up of the tricuspid complex pulmonary valve false tendon and septomarginal trabecula，et al. The tricuspid complex was built up of the tricuspid valve ring and valve chordae tendinease and papillary muscles. The average length of tricuspid valve ring was 71.03 ± 14.20mm. The average length of pulmonary valve ring was 35. 97 ± 8.17mm. 3. The main anatomi-cal structures of the right and left atrium in canine were composed of the before and after vena cava pulmonary veins coronary sinus and fossa ovalis. Before and after the inferior vena cava the perioral diameter were 43.91 ± 10.17mm and 37.67 ± 10.54 mm. The average of pulmonary veins was 29.44± 12.71mnr Coronary sinus circumference was 14.12 ± 4.00 mm. Coronary sinus which was round the mouth accounted for 89.7%, the lamiaceae accounted for 10.3%. Fossa ovalis was found in 100%.Conclusion The main anatomical structure of the Canine hearts cavity is similar to that of human heart in spite of the difference in size and the total number of left ventricular false tendon and chordae tendinease.

Key words: Dog heart, Main anatomical structure, Comparison