Diseases of cattle, sheep, goats and swine

by G. Moussu; Jno. A. W. Dollar

The pericardial sac touches the extremity of the sternum where it is in immediate contact with the lower insertion of the diaphragm. This peculiar arrangement favours the development of pericarditis due to foreign bodies.

On the left side the pericardial sac may come in direct contact with the internal surface of the thoracic cavity opposite the lower extremity of the third, fourth, and sometimes fifth ribs. At all other points the pulmonary lobes, as expanded during inspiration, separate it from the thoracic wall.

Although the pericardium and heart are situated in the median plane, percussion and auscultation should be performed on the left side, since the anterior and cardiac lobes of the left lung are less developed than those of the right; but the heart can be auscultated on the right side, as is advisable at times.

In the healthy ox there exists an area of the left thoracic wall which may be called the cardiac zone, on a level with which are heard the normal heart sounds. In diseased conditions this zone or area may vary in size, and the sounds may be modified.

The heart can be examined by inspection, palpation, percussion, and auscultation.

Under ordinary conditions inspection reveals nothing in well-nourished animals; but in very thin subjects and in those suffering from recent cardiac lesions or pseudo-pericarditis, a rhythmic movement of the chest wall is sometimes detected.

Palpation is performed by placing the open hand on the cardiac zone. In this way the cardiac shock can be felt, its degree of intensity judged, and, in an imperfect manner, its rhythm.

Percussion by means of the fingers or a pleximeter discloses the extent of the physiological area of partial dulness, due to the presence of the heart, as well as its variations in pathological conditions, particularly in pericarditis with marked exudation.

Fig. 173.—Schema of a section through the chest opposite the heart. Pg, Left lung; Pd, right lung; cp, right and left pleural cavities; P, pericardium; l, l¹, cardiac lobes of the lung interposed between the pericardium and thoracic wall.