236 DISEASES OF THE HORSE. 



ADVENTITIOUS GROWTHS IX THE HEAKT. 



Fibrous, cartilaginous, and tony formations have been observed in 

 some rare instances in the muscular tissue. Isolated calcareous masses 

 have sometimes been embedded in the cardiac walls. Fibrinous 

 coagula and polypous concretions may be found in the cavities of the 

 heart. The former consist of coagulated fibrin, separated from the 

 mass of blood, of a whitish or yellowish white color, translucent, of a 

 jellylike consistence, and having a nucleus in the center. They may 

 slightly adhere to the surface of the cavity, from which they can 

 easily be separated without altering the structure of the endocardium. 

 They probably result from an excess of coagulability of fibrin, which 

 is produced by an organization of the lymph during exudation. They 

 are usually found in the right auricle and ventricle. 



Polypous concretions are firmer than in the preceding, more opaque, 

 of a fibrous texture, and may be composed of successive layers. In 

 some instances they are exceedingly minute, while in others the_y 

 almost fill one or more of the cavities. Their color is usually white, 

 but occasionally red from the presence of blood. They firmly adhere 

 to the endocardium, and when detached from it give it a torn appear- 

 ance. Occasionally, a vascular communication seems to exist between 

 them and the substance of the heart. They may be the result of 

 fibrinous exudation from inflammation of the inner surface of the 

 heart or the coagulation of a portion of the blood which afterwards 

 contracts adhesion with the heart. These concretions prove a source 

 of great inconvenience and often danger, no matter how formed. 

 They cause a diminutioji in the cavity in which they are found, thus 

 narrowing the orifice through which the blood passes, or preventing a 

 proper coaptation of the valves, which may produce most serious 

 valvular disease. 



Symptoms. — THese are frequently uncertain; they may, however, 

 be susjDected when the action of the heart suddenly becomes embar- 

 rassed with irregular and confused pulsations, great difficulty of 

 breathing, and the usual signs dependent upon the imperfect arterial- 

 ization of the blood. 



Treatment. — Stimulants, whisky, or carbonate of ammonia may be 

 of service. 



PALPITATION OF THE HEART. 



This is a tumultuous and usually irregular beating of the heart. It 

 may be due to a variety of causes, both functional and organic. It 

 may occur as a result of indigestion, fright, increased nervousness, 

 sudden excitement, excessive speeding, etc. (See " Thumps," pp. 

 141, 205.) 



Symptoms. — The heart may act with such violence that each beat 

 may jar the whole body of the animal; very commonly it may be 



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