84 CLINICAL DIAGNOSTICS. 



directed from the right, in front and above to the left, backward 

 and downward, the left side of the apex reaching the chest wall. 



Horse. The base of the heart lies below the upper half of 

 the height of the chest cavity, resting against the thoracic wall 

 between the 4th and 5th intercostal space. The point of contact 

 occupies a surface of about 10 cm high and 6-8 cm broad. (See 

 Fig. 27, page 87). 



Ox and small ruminants. The heart is smaller and 

 does not extend quite as far back as the 6th rib, its base, however, 

 extends to the median line of the chest. Between the 4th and 5th 

 ribs it comes in immediate contact with the thoracic wall. (See 

 Fig. 26.) 



Dog. The heart is of rounder form and lies at an angle 

 of -I0--I5 3 with the sternum, touching the chest wall along a narrow 

 strip from the 4th to the 7th ribs. The apex is below the 6th 

 intercostal space. (See Fig. — .) 



Palpation of the heart's region. The beat of the heart can 

 be felt by laying the flat of the hand over the cardiac region. 

 Inasmuch as the anconeus muscles partly cover the region, the 

 hand should be placed between them and the chest wall. In 

 the depths a dull thud will be felt, produced by the thumping 

 of the heart against the chest wall. The beat is due to a con- 

 traction of the heart's muscles which causes a slight torsion of 

 the organ to the left, bringing the left side, not the apex, 

 in contact with the wall of the chest. The beat can best be felt 

 in all animals at the Sth intercostal space, just above the union 

 of the ribs with their cartilages. The force with which the beat 

 can be felt depends upon the condition of the animal as to flesh, 

 it being more plainly marked in thin animals, and just after severe 

 exercise or excitement. Only in the dog can the heart's beat be 

 felt normally on the right side. 



In swine and fowls the heart is palpated to determine its 

 action, as the pulse in these animals can not be felt. In swine 

 the heart beats 60-100, and in fowls 120-160 times per minute. 

 Great variations are, however, noted due to the excitability of 

 these animals. 



The force of the heart's beat can be in- 

 creased or diminished. When the force of the beat is much 

 increased a palpitation of the heart is spoken of. It occurs : 



1. In hypertrophy of the heart (here combined with 

 strong pulse). 



2. In heart's weakness, the muscles of the organ un- 

 dergoing spasm-like contractions incapable of properly pro- 

 pelling the blood to the periphery, the pulse being small. The 

 condition is seen in acute myocarditis, endocarditis and peri- 

 carditis. 



