MYOSITIS. 423 



Cause. — I only know of one cause of Myositis, and that 

 is — exerting the animal beyond its natural powers. Taking a 

 horse which may have been used for several months, or even 

 years, at slow work, and without a moment's preparation driving 

 him with great speed for a considerable distance ; or subjecting 

 a horse to the same treatment immediately after taking him 

 from a long run at grass, is all but certain to produce the malady 

 in question. One of the worst cases of the disease I ever saw, 

 occurred to a mare which was taken from slow work, to which 

 she had been used for some time. She was put into the shafts 

 of a gig, and driven five miles and a quarter over a hilly 

 country in twenty minutes. The same cause is also just as 

 likely to produce inflammation of the feet. 



Hunters, race horses, and cab horses, are perhaps more fre- 

 quently affected with Myositis than any other class of animals. 

 In certain cases where the patient has died, I have found the 

 following appearances : — muscular tissue lacerated and softened, 

 and attended with an effusion of serum and dark blood like 

 stains in the muscular substance. 



Symptoms of Local Myosities. — The muscles most 

 frequently affected locally are those of the shoulders — such 

 as the serratus magnus^ the latissimus dorsi, and the extensor 

 hracMi. 



The pulse and respirations are always disturbed : the degree 

 of disturbance depending upon the amount of injury inflicted 

 upon the muscles ; the breathing is short and hurried, but the 

 respiratory murmur is clear throughout the chest, except when 

 the disease is associated with pneumonia or bronchial disease 

 (which it sometimes is), when mucous rales within the trachea 

 and bronchial tubes will be present. If not associated, how- 

 ever, with either of these maladies no such sounds will be heard, 



