DISEASES OF THE HEART. 233 



be superseded by tlie nitrate of potassa, in half-ounce doses, for the 

 following week, or until the urinary secretion becomes abnormally 

 profuse. Where the disease is associated with rheumatism, 2-dram 

 doses of salicylate of soda may be substituted for the chlorate of 

 potassa. To guard against chronic induration of the valves, the 

 iodide of potassa, in 1 to 2 dram do^s, should be given early in the 

 disease, and may be repeated two or three times a day for several 

 weeks. A\lien chi'onic effects remain after the acute stage has passed 

 this drug becomes indispensable. 



When dropsy of the limbs develops, it is due to weakened circula- 

 tion or functional impairment of the kidneys. When there is much 

 weakness in the action of the heart, or general debility is marked, the 

 iodide of iron, in 1-dram doses, combined with hydrastis, 3 drams, 

 may be given three times a day. Arsenic, in 5-grain doses twice a 

 day, will give excellent results in some cases of weak heart associated 

 with difficult breathing. In all cases absolute rest and warm stabling, 

 with comfortable clothing, become necessary, and freedom from 

 work should be allowed for a long time after all symptoms have dis- 

 appeared. 



PERICARDITIS, OR INFLAMMATION OF THE SAC INCLOSING THE HEART. 



Causes. — Pericarditis may be induced by cold and damp stabling, 

 exposure and fatigue, from wounds caused by broken ribs, etc. Gen- 

 erally, however, it is associated with an attack of influenza, rheuma- 

 tism, pleuritis, etc. 



Symptotns. — Usually the disease manifests itself abruptly by a 

 Vjrief stage of chills coincident wdth pain in moving, a short painful 

 cough, rapid and short breathing, and high temperature, with a 

 rapid and hard pulse. In the early stages of the disease the pulse is 

 regular in beat ; later, when there is much exudation present in the 

 pericardial sac, the heart-beat becomes muffled, and may be of a double 

 or rebounding character. By placing the ear against the left side 

 of the chest behind the elbow a rasping sound may be heard, cor- 

 responding to the frequency of the heart-beat. This is knowm as a 

 friction sound. Between the second and fourth days this sound may 

 disappear, due to a distension of the pericardium by an exudate or 

 serous effusion. As soon as this effusion partly fills the pericardium, 

 percussion will reveal an abnormally increased area of dullness over 

 the region of the heart, the heart-beats become less perceptible than in 

 health, and in some cases a splashing or flapping sound may become 

 audible. 



If the effusion becomes absorbed, the friction sound usually recurs 

 for a short time; this friction may often be felt by applying the 

 hand to the side of the chest. In a few cases clonic spasms of the 

 muscles of the neck may be present. In acute pericarditis, when the 

 effusion is rapid and excessive, the animal may die in a few days or 



