Diseases of the Heart and Organs of Circulation. 417 



sions, dropsies and difficult breathing. The imperfect supply of 

 blood to the muscles of the extremities, sometimes brings about an 

 unsteadiness of gait in the hind limbs when the animal is trotted 

 for a short distance, and sometimes cramps supervene. 



Continued coldness of the limbs, and a filling or thickening 

 first of the hind limbs then of the fore and lastly of the chest and 

 belly and of the skin beneath their dependent parts, are useful 

 indications. 



Shortness of breath and inability to proceed when trotted or 

 galloped on hard ground, or when walked up hill, the animal being 

 in fair condition, without fever or cough, but subject to cold 

 extremities and a venous pulse in the jugulars, almost certainly 

 indicates insufficiency of the auriculo-ventricular valves on the 

 right side of the heart. 



Vertigo, megrims, or giddiness may be caused by heart disease. 

 The horse without having sustained any pressure on the veins of 

 the neck by the collar, and having had no previous symptom of 

 brain disease suddenly reels in harness and perhaps falls. There 

 are the cold and engorged limbs or a tendency to their engorge- 

 ment as in the former case. The attacks recur when the horse 

 is put to the same exertion, and he proves utterly worthless. In 

 such cases a careful examination of the pulse and heart sounds 

 will complete the chain of evidence. 



An" almost constant feature of chronic heart disease is a con- 

 dition of dullness, sluggishness, and in many cases, curiously 

 enough, a tendency to lay on fat, so that although the patient is 

 unfit to work, he appears to enjoy excellent general health to 

 which a period is only put by sudden death. 



Affections of the heart are primarily divisible into functional 

 and structural disorders. 



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