DISEASES OF THE HEART AND BLOOD VESSELS. 439 



the animal will pant after tlie least exercise. Nothing can be done. 

 Death is liable to occur from suffocation when tiie horse is put at hard 

 work. 



VII. Cyanosis, or Blue Disease. 



This is very uncommon in the horse. Tiie circulation peculiar to foetal 

 life does not change at birth, as it ought to, ])y the closing of atemporary 

 opening between the right and left sides of the heart. The failure of 

 this opening to close at birth allows the venus blood to pass right through 

 into the arteries without going through the lungs to be aerated, and 

 gives a blue color to all parts that ought to be pink — the eye-lids, 

 mouth, etc. The animal does not live long, but dies in the course of a 

 week or two. The surface of the body never gets warm ; the respirations 

 are usually slow, and there is great weakness, which increases as death 

 approaches. 



VIII. Rupture of the Heart. 



Horses are liable to rupture the heart at the time of any sudden exer- 

 tion or jerk. Those with heaves are the most often affected. The right 

 ventricle and the auricles are most liable to it : the left ventricle has walls 

 so thick that rupture of them rarely takes place. Nothing can be done 

 for it. Instant death is the result. 



IX. Rupture of a Blood Vessel. 



This is a more common accident than any other pertaining to the heart 

 and blood vessels. Any very severe exertion, such as racing, trottino-, 

 jumping, extra hard pulling etc., is often interrupted and brought to a 

 stand-still by the rupture of a blood vessel. Those most lial)lc to rupture 

 are the arteries and veins in the abdominal region of the bodv ; the next 

 those in the chest, head, etc. There is no way of foreseeing its approach 

 nor of obviating its effects, which are always fatal from internal hemor- 

 rhage. Having the horse in as tine condition physically as possible for any 

 extra exertion is the only way of diminishing the liability to its occurence. 



X. Aneurism. 



Arteries are liable to get weak in their walls (a tendency to rupture), 

 and dilatation is the result, owing to the immense pressure of the blood 

 from the action of the heart. The large arteries in the abdominal cavity 

 near the back arc most often affected in this way. 



How to know it. — If it is suspected, examine the parts internally by 

 the hand inserted in the rectum ; a large bulge or elliptical enlargement 

 and distinct pulsations are felt when aneurism exists. The swelling is 

 soft and compressible. 



