66S SPORADIC DISEASES. 



but I noticed that tliere was a continual spasmodic twitching of 

 the above-mentioned muscles, as well as a dread on the part of 

 the animal when suddenly approached. On examining the 

 heart and circulation there was a distinct jugular pulse, great 

 irregularity of the heart's action, a loud cooing or blowing 

 sound and strong impulse, indicative of hypertrophy, and such 

 a want of correspondence between the cardiac energy and feeble 

 pulse as to lead me to the conclusion that the horse was suffering 

 from valvular incompetency or impediment, to overcome which 

 hypertrophy of the cardiac walls had become established. 



Angina pectoris is su^jposed by physicians to be due to 

 dilatation of the cardiac cavities, degeneration of the walls, some 

 condition of the aortic valves which permits the regurgitation of 

 blood into the heart, or some sudden impediment to the coronary 

 circulation. The condition of the horse in question pointed 

 to the conclusion that the cause was due to aortic impediment. 

 Unfortunately I lost sight of the animal, and I am unable to 

 confirm this view by any post mortem examination. The latest 

 theories upon the cause of this painful malady are as follows : — 



(1.) Neuralgic affection, commencing for the most part in 

 pneumogastric nerve, and spreading in different directions. 



(2.) That it is due to such an acceleration of the movements 

 of the blood, by exercise or otherwise, that it arrives at the heart 

 faster than it can be transmitted onwards, and accumulates in 

 its cavities so as painfully to distend them. 



(3.) Ossification of the coronary arteries, which, by failing to 

 supply sufficient blood to the cardiac walls, so impairs their 

 strength that the heart is incapable of contracting upon the 

 increased quantity of blood within its cavities, brought about 

 by exertion or excitement. 



CYANOSIS. 



The blue disease described by some veterinary authors, and 

 depending upon non-closure of the foramen ovale, is a condition 

 which is only met with, and that very rarely, in very young 

 animals. It is due to admixture of the venous with the arterial 

 blood in the left cavities of the heart, owing to the foramen of 

 communication existing in foetal life remaining pervious after 

 birth. It is manifested by blueness of the visible mucous 



