DISEASES OF HORSES 247 



violence likely to acquire increased severity. Severe inflammation, 

 with suppuration, may follow, which, filling up the cavity, the walls 

 will become thickened and hard, resulting in the formation of a 

 tumor. The elbow, the knee, and the hock are the parts of the body 

 where these lesions are ordinarily found, and on account of their 

 peculiar shape and the position they occupy they have received the 

 denomination of capped. They will be considered in their peculiar 

 aspect. 



CAPPED ELBOW. 



Capped elbow, or "shoe boil," is a term applied to an enlarge- 

 ment often found at the point of the elbow. This lesion is due to 

 injury or pressure of the part while it is resting on the ground. The 

 horse, unlike the cow, does not rest directly on the under surface of 

 the sternum, or breastbone, on account of its sharp, ridgelike for- 

 mation. He rests more on the side of the breastbone and chest, and 

 consequently the leg which is flexed under the body is subject to 

 considerable pressure. If the leg is flexed under the body so that 

 the hoof or shoe is directly in contact with the elbow, which may 

 occur in horses having an extremely long canon bone or excessive 

 length in the shoes, the greater part of the weight of the chest is 

 concentrated at this point and the pressure may cause a bruise or an 

 inflammation. 



Symptoms. Under these conditions the point of the elbow may 

 become swollen and tender and exhibit heat and pain. This swell- 

 ing may not only cover the point of the elbow, but sometimes reaches 

 the axilla and assumes such proportions that there is great difficulty 

 in using the leg, the animal showing signs of lameness even to the 

 extent of the circumflex step, as in shoulder lameness. This ede- 

 matous condition, however, does not remain stationary. It may by 

 degrees subside or perhaps disappear. In the first instance it will 

 become more distinctly defined, with better marked boundaries, 

 until it is reduced to a soft, round, fluctuating tumor, with or with- 

 out heat or pain. 



Various changes will follow the opening of the tumor and the 

 escape of its contents. In a majority of cases the process of cica- 

 trization will take place, and the cavity fill up by granulation, the 

 discharge, at first abundant, gradually diminishing and the wound 

 closing, usaally without leaving any mark. At times, however, and 

 especially if the disease has several times repeated its course, there 

 may remain a pendulous sac, partly obliterated, which a sufficient 

 amount of excitement or irritation may soon restore to its previous 

 dimensions and condition. 



In other cases an entirely different process takes place. The 

 walls of the cavity, cyst, or abscess become ulcerated and thickened, 

 the granulations of the sac become fibrous in their structure and fill 

 up the cavity, and it assumes the character of a hard tumor on the 

 back of the elbow, sometimes partly and sometimes entirely covered 

 by the skin. It is fibrous in its nature, painless to the touch, well 

 defined in its contour, and may vary in size from that of a small 

 apple to that of a child's head. 



