142 DISEASES OF THE HORSE. 



Diseases of the Heart. 



[Amongst all the diseases to which the horse is liable, there 

 are none more obscure in their symptoms, or more fatal in their 

 terminations, than affections of the heart. 



They rarely, however, occur, but as connected with other 

 diseases, the danger of Avhich they greatly increase, whilst the 

 symptoms are rendered more obscure. 



Dropsy of the heart, or water in the pericardium, often ac- 

 companies hydrothorax, and sometimes occurs in inflammation 

 of the lungs and pleura ; the water being occcasionally so great 

 in quantity as absolutely to choke the action of the heart. We 

 sometimes find lymph floating in the water, or streaks of lymph 

 adhering to the pericardium. 



This disease often accompanies enlargement of the heart itself, 

 which organ sometimes weighs double its usual gravity. 



Hypertrophy. — With an increased size we may have either 

 a dilatation or a diminution of the cavities of the heart. 



The heart is sometimes found not only gretitly increased in 

 size, but quite altered in its appearance, presenting an irregular 

 fungous mass. In a case of this sort that I met with a few years 

 since, the beating of the heart was particularly loud, hollow, 

 and thumping, though not greatly increased in numl)cr. The 

 seat of disease was pointed out by the apparently laborious action 

 of the heart. 



Mr. Pritchard, who has communicated several interesting 

 cases of disease of the heart, observes, in the 6th vol. of the 

 Veterinarian, on the subject of hypertrophy, or enlargement of 

 the heart: — "It has always struck me forcibly that over- 

 exertion is the principal exciting cause of hypertrophy, and of 

 dilatation ; and, I may add, the possibility that the original 

 structure of the heart may, in some subjects, be unequal in 

 power to the office it is designed to perform. 



" This opinion is strongly supported. Horses, particularly 

 those employed in quick di'aught, are commonly called on to 

 perform arduous tasks with full stomachs, by which the free 

 action of the lungs is considerably impeded ; thus, obstruction 

 being given to the circulation through the pulmonary vessels, 

 corresponding increase of force in the action of the heart is the 

 consequence. 



" The first inconvenience felt by the animal during exertion 

 is in the respiratory organs, and this more especially when the 

 stomach is distended, as then the cavity of the chest is di- 

 minished : the lungs are not inflated with ease to the extent 

 required for the blood to flow uninterruptedly through them. 



" Hypertrophy of the right side of the heart is liable to be con- 

 founded with pneumonia, as the lungs are readily affected in this 



