The base is broader and the length from the base to apex is shorter.
The long axis is more oblique.
The anterior border is more strongly convex.
It weighs about 2.9 kg to 3.1 kg.
The intermediate groove is absent.
Instead of os cordis, the aortic ring contains on the right side a plate of cartilage.
Sometimes a small plate of cartialge is present on the left side.
Dog
It is ovoid in shape. The apex is blunt and rounded.
The long axis is very oblique. The base faces the thoracic inlet.
The apex is in close relation to the diaphragm at its sternal part.
The left (ventral) and right (dorsal) longitudinal grooves meet with each other.
An intermediate groove is present.
The weight of the heart of a medium sized dog is 150 to 180 gms. The tricuspid valve has two chief cusps and three or four small ones.
There are four musculi papillaris in the right ventricle, all of which spring from the septal wall.
The bicuspid valve consists of two large cusps and four or five small ones.
There are two musculi papillaris in the left ventricle, both of which arise from the lateral wall.
Fowl
It is proportionately larger.
It has the form of an acute cone and lies partly between the two lobes of the liver and partly anterior to them.
The apex is directed backwards and slightly to the left of the median line.
There are two anterior vena cavae and a single posterior vena cava.
A muscular fold called the eustachian valve is found to the right of the opening of the posterior vena cava.
The right atrio ventricular opening is a curved slit and its valve is a muscular leaf, which has neither cusps nor chordae tendinae.
Musculi papillaris are absent in the right ventricle. The pulmonary artery opening has three semilunar cusps.
The left atrium is smaller than the right and the two pulmonary veins open into it by a common opening. The left atrio-ventricular valve is guarded by membranous cusps corresponding to the bicuspid valve of mammals.
The musculi papillaris and chorda tendinae are present in the left ventricle.
