CHAPTER LIV. 



SPOEADIC DISEASED— continued. 



LOCAL BISY.AS'ES— continued. 



(K.) DISEASES OF THE HEART AND ITS MEMBRANES. 



The weight of the heart of the horse varies according to the 

 animal's weight and size — from 8 to 20 lbs ; the average, how- 

 ever, is about 10 lbs. In the ok, sheep, and pig the weight of 

 the heart is to that of the weight of the body as 1 in 220, and in 

 the dog as 1 in 90. Anything much above this average is 

 indicative of hypertrophy. 



Heart diseases, although rare in the lower animals compared 

 with their frequency in man, and much more difficult of 

 diagnosis, are neither infrequent nor unimportant. 



For the convenience of description they may be arranged 

 under two heads, namely — 1st. Diseases of the heart and valves ; 

 2d. Diseases of the cardiac membranes. 



1st. Diseases of the heart are divided into functional and 

 organic. 



(a.) Functional derangement of the heart, characterised by 

 palpitations, irregularity, or intermittence of the pulse, may arise 

 from debility, indigestion, blood poisoning, as in purpura, hjemo- 

 albuminuria, epizootic catarrhal fever, &c. 



Palpitation of the heart is often due to dyspepsia, disappear- 

 ing with the indigestion and reappearing with another attack, 

 both in the horse and dog. It also arises from nervousness, and if 

 a nervous animal be approached rapidly and roughly, the beatings 

 of the heart are often distinctly heard ; and if tlie pulse be felt, 

 it may be irregular and intermitting. If one were immediately 

 to form a diagnosis that these results were due to heart disease, 

 a few minutes' further observation would point out the error. 



Palpitations and irregularities are symptomatic of other dis- 

 orders, when they occur occasionally only, and when other signs 



