214 THE EXTERIOR OF THE HORSE. 



which they give to the parts and the difficulties which are afterwards experienced 

 in the application of the collar. 



At other times, this region may be the seat of cold abscesses, disabling the 

 horse for a variable period during their formation. These are sometimes true 

 fibromata, from the induration of the subcutaneous connective tissue. Of a 

 chronic character at first, they soon become so sensitive to the pressure of the 

 collar as to render the most docile horse intractable. 



The most serious of these tumors are those at the point of the shoulder, 

 from the fact of the enormous volume which they may acquire, the dangers 

 which their extirpation presents, and the difficulties experienced in healing the 

 consecutive wounds, which are always more or less deep. They are caused by 

 the pressure of a collar badly adjusted, insufficiently padded, or too heavy. 



It is not necessary to confound these tumors with diffuse enlargements of the 

 scapulo-humeral articulation, as, for instance, with the particular affection known 

 under the clinical but improper names sprained shoulder, shoulder-slip, which 

 is accompanied by a lameness in which the anterior member is markedly 

 abducted when it is extended, instead of moving in a direction parallel to that 

 of the body. This movement, which is called mowing, is due to the immobiliza- 

 tion of the arm upon the shoulder or the sides of the thorax, and is a symptom 

 of diverse lesions of the ligaments, the muscles, the bones, the blood-vessels, or 

 the nerves. Although this phenomenon may be quite rare, the point of the 

 shoulder none the less often carries the evidence of the treatment employed to 

 combat it. Such are the marks of cauterization, setons, rowels, and blisters, which 

 occasion decortications, accidental white spots, or cicatrices of a particular form 

 upon a more or less extensive area of this region. The gravest blemishes, 

 above all, are traces of the actual cautery, except in the Barb horses, in which 

 this therapeutic agent is always applied as a means of prevention against diseases of 

 the articulation. It is important, in such cases, to examine carefully the inferior 

 portion of the corresponding member, for the scapular lesion may be a feint for 

 another disease, or, what is more frequent, an indication of an error of diagnosis. 



Let us mention, also, paralysis of the shoulder and atrophy of the super- and 

 sub-spinati muscles, which are sometimes observed, but which produce no lame- 



B. The Arm. 



Situation; Limits; Anatomical Base; Form. The arm, 

 slightly detached from the trunk, is situated between the shoulder, with 

 which it is confounded, and the/orearm, from which it is separated by 

 an oblique furrow in front. 



Limited in front by the breast and the axilla, behind by the sides of the 

 thorax, and lower down by the elbow, it contains for its osseous base a long and 

 voluminous bone, the humerus, surrounded by two sets of muscles : the first, 

 coming from the shoulder, the neck, the side of the thorax, and the sternum, 

 moves this region in every direction ; the second, extending to the forearm and 

 the foot, regulates the movements of the inferior segments of the member. 



Movements. When the thoracic member is carried forward, as 

 in walking, the humerus is first flexed, then its inferior extremity 



