Overview
The bovine heart (cor) is conical, with a relatively pointed apex formed by the left ventricle. Wrapped in the pericardium, it fills the middle mediastinum between the 3rd and 6th intercostal spaces, mostly left of the median plane. The base, where the great vessels leave, faces dorsally; the apex points ventrally towards the sternum. Caudally, the diaphragm separates it from the reticulum, which lies very close to the apex.
Parts
- Right atrium and ventricle: receive blood from the venae cavae and the coronary sinus and pump it into the pulmonary trunk. In ruminants the left azygos vein drains into the coronary sinus.
- Left atrium and ventricle: the left atrium receives the pulmonary veins; the thick-walled left ventricle forms the apex and ejects blood into the aorta.
- Valves: tricuspid (right atrioventricular), mitral (left atrioventricular), pulmonary and aortic.
- Cardiac bones (ossa cordis): cattle have two, a larger right one and a smaller left one, in the fibrous skeleton around the aortic orifice.
- Coronary arteries: in cattle the left coronary artery is dominant and gives both the paraconal and the subsinuosal interventricular branches.
Clinical relevance
- Auscultation: the thoracic limb covers most of the cardiac area, so the stethoscope is pushed under the triceps muscle, above the elbow, mainly on the left side. The resting heart rate of the adult is around 60–80 bpm.
- Traumatic pericarditis: a metal foreign body that perforates the reticulum and diaphragm reaches the pericardium and causes fibrinopurulent pericarditis. Signs are muffled heart sounds, splashing or friction sounds, tachycardia, jugular distension and oedema of the brisket and dewlap (right heart failure). The prognosis is poor.
- Bacterial endocarditis: mainly affects the tricuspid valve; it is associated with chronic septic foci (liver abscesses, mastitis, foot lesions) and Trueperella pyogenes.
- High mountain disease (brisket disease): in cattle raised at high altitude, hypoxia causes pulmonary hypertension and right heart failure with brisket oedema.
- Lymphoma: in enzootic bovine leukosis the right atrium is a characteristic site of tumour infiltrates.