354 DISEASES OF THE HOKSE. 



which consists principally in a hypersecretion of their contents and 

 an increase in dimensions, and they may undergo peculiar patho- 

 logical changes of such a character as to disable an animal, and in 

 many instances to cause serious blemishes which can not but depre- 

 ciate his value. These growths, which are known as hygromata, may 

 result from external violence, as blows or bruises, and may appear in 

 the form of small, soft tumors, painless and not inflammatory in 

 character, but, by a repetition of the cause or renewal of violence, 

 likely to acquire increased severity. Severe inflammation, with sup- 

 puration, 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 denomina- 

 tion of " capped^ They will be considered in their peculiar aspect. 



CAPPED ELBOW. 



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

 often found at the point of the elbow. 



Cause. — 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 formation. 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 witK the 

 elbow, which may occur in horses having an extremely long cannon 

 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 swelling 

 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 edematous con- 

 dition, 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 without heat or 

 pain. There is then either a bloody or serous tumor or a purulent 

 collection, and following the puncture of its walls with the knife 

 there will be an escape of blood, of serum, or of pus, as the case may 

 be, in variable quantities. In either case, but j)rincipally in that of 

 the cystic form, the tumor will be found to be subdivided by septa, or 

 bands running in various directions. 



