292 Veterinary Medicine. 



the horn or the depth and spring of the rib. The lower animals 

 are further subject to congenital malformations and imperfections 

 and to deposits of morbid material around the heart or in its sub- 

 stance so as to impair its healthy action. 



Horses and dogs have special predisposing causes in the violent 

 and prolonged exertion to which they are habitually exposed. 

 The quiet sluggish and nonexcitable ox and pig meet with dan- 

 gers no less real though of a different kind in the overfeeding 

 which induces fatty degeneration of the heart as of other muscu- 

 lar tissues. The larger ruminants are further endangered by 

 their propensity to swallow needles and other sharp pointed bodies 

 which ultimately reach and penetrate the heart. 



The prevalence of heart disease in animals may be deduced 

 from the fact that out of 150 horses, oxen and dogs dissected at 

 Montfaugon by lycblanc in 1840, not less than one twentieth pre- 

 sented cardiac lesions. The supposition of an immunity of the 

 lower animals has been largely due to the heavy muscular shoul- 

 der of quadrupeds which covers the upper and anterior regions of 

 the heart shutting them out from physical exploration. In man 

 the entire heart and connecting blood vessels are so open to exam- 

 ination that the physician can pronounce with the greatest accu- 

 racy not only concerning the existence of disease, but also its pre- 

 cise locality and nature. In the quadruped no such facility is 

 open to us, and veterinarians have too generally refused to face the 

 difficulty, preferring to ignore heart diseases, or still worse seek- 

 ing to cover their ignorance by the assertion that such affections 

 rarely exist. Now however we not only know that heart diseases 

 are much more frequent in the lower animals than heretofore be- 

 lieved, but that as a general rule they are sufficiently manifested 

 and recognizable by their distinctive symptoms. 



Position and exposure of the heart. In the horse the heart 

 has only its apex and a small portion of its left ventricle approach- 

 ed to the surface of the chest, at a point where it is felt to beat 

 behind the left elbow. The apex approaches the surface in the 

 interval between the fifth and sixth ribs and close above the 

 breast bone. The posterior border of the ventricle follows a nearly 

 vertical line upwards from this point, while the anterior border 

 has a direction upward and forward crossing diagonally over the 

 fifth rib. The part of the ventricle exposed extends about three 



