DISEASES OF THE HEART 



of sufficient exercise conduces very much to the progress of the malady. 

 The anatomical changes resulting from the disease are extremely marked, 

 and very easily recognized by the use of the microscope. The muscular 

 walls are, as in the case of fatty infiltration, commonly paler in colour 

 than the normal structure, and often present a faded yellow or pale-brown 

 tint; the muscle is easily torn or broken down, and has been compared 

 in texture to wet brown paper. Under the microscope the muscular fibres, 

 instead of being well defined with perfectly distinct transverse markings, 

 present a granular appearance owing to the presence of minute granules 

 of fat in their structure, and in some advanced cases every trace of the 

 fibrillated appearance of the normal 

 fibre has become obscured, and only 

 a mass of fat granules can be recog- 

 nized. 



Symptoms. — It is well known to 

 pathologists that fatty degeneration 

 may advance to a considerable extent 

 without any symptoms becoming ap- 

 parent. An animal may die suddenly 

 from the disease the existence of 

 which has not been suspected during 

 its life. This will be quite intelli- 

 gible to the veterinarian, as the oc- 

 casional unpleasant sensations which 

 are recognized by the human patient 

 over the cardiac regions would find 

 no expression in the horse. Occa- 

 sional attacks of what in the human subject is described as " angina pec- 

 toris " may occur in the horse, but would either be, as is usually the 

 case, unnoticed, or, if observed, would be referred to an attack of colic 

 or probably a spasm of the diaphragm. 



Williams, in his book on Tlie Practice of Veterinary Medicine, records 

 one case which came under his notice, which he considered to be an in- 

 stance of angina pectoris in a well-defined form. The animal was an aged 

 cart-horse, which for twelve months had done very little work, owing to 

 the fact that when he was excited by work or exertion, he suffered extreme 

 pain in the left fore-limb, the muscles of which, with the muscles of the 

 chest (pectorals), became violently convulsed. The paroxysm seldom 

 occurred when the animal was at rest, but there was a continual twitching 

 of the muscles, and the animal appeared to dread being approached. On 

 examination by auscultation, a loud cooing or blowing sound was heard 



2 2 



Fig. 195.— Fatty Degeneration of Muscle 



Muscle Fibre (healthy). '- - Muscle Fibres infiltrated 

 with fatty granules. 



