SPECIAL CLINICAL EXAMINATION. 83 



but merely a passive undulation due to a regurgitation of the 

 blood in the form of waves. The presystolic appearance of 

 the pulse movement characterizes it, therefore it should al- 

 ways be compared with the arterial pulse. The collapse of 

 the vein is synchronous with the arterial pulse. 



The undulation of the jugular vein is intensified in the 

 ox and becomes apparent in other animals when the above 

 cited condition prevails, induced by a morbid congestion of 

 the blood at the heart. In the horse the venous pulse is seen 

 near the aperture of the thorax (lower portion of the neck). 



A true (positive) venous pulse is pathological. It is 

 coincident with the heart's systole, and is produced by a de- 

 fective closing of the atrio-ventricular valves, the blood re- 

 gurgitating into the auricle. True venous pulse is 

 a characteristic symptom of tricuspid in- 

 sufficiency. 



Fie. 26. 



wyywv 



Venous Pulse— Horse. 



The valves in the jugulars do not prevent the flowing 

 back of the blood, as they are commonly not well developed, 

 and if the vein be greatly distended they cannot close the 

 lumen of the vessel. 



III. The Heart. 



The heart is examined by palpation, percussion 

 and auscultation. 



Anatomical. In all domestic animals the heart lies in the ven- 

 tral portion of the thoracic cavity from the third and sixth 

 ribs in the dog extending to the seventh rib. The great mass 

 of the organ (3-5) lies to the left of the median line so that it 

 approaches nearer the left thoracic wall than the right one. It 

 does not occupy a perpendicular position, but an obj'que one 



