64 DISEASES OF THE SYNOVIAL MEMBRANES AND ARTICULATIONS. 



cover others. Whether the subject be a bull or a cow, if the stationary 

 animal suddenly moves to one side, or if the moving animal is frightened 

 by the appearance of a dog, one of the front limbs may be violently 

 dragged away from the body ; the resistance of the capsular ligament 

 and internal muscles of the shoulder may be overcome and luxation 

 produced. 



Symptoms. Symptoms are immediately apparent : no weight can be 

 placed on the injured limb, and the animal moves on three legs. All 

 muscular action is avoided, the limb is slightly shortened as a conse- 

 quence of the head of the humerus slipping behind the shoulder, which 

 is held rigidly during movement ; the points of the claws are dragged 

 along the ground. 



On local examination the point of the shoulder appears to be deformed 

 and outwardly displaced, in consequence of the pressure exercised by the 

 displaced head of the humerus. Below the glenoid cavity and coracoid 

 process lies a depression, at the base of which the displaced humerus 

 can be felt. This depression, however, is soon filled up by the sero- 

 sanguinolent effusion consequent on luxation. 



Diagnosis. Bearing in mind the conditions to which the accident is 

 due, the diagnosis presents no great difficulty. 



Prognosis. The prognosis is grave, for although it is relatively easy 

 to reduce the displacement, it is very difficult to keep the joint fixed 

 in j)osition. 



Treatment. To effect reduction, the animal should be cast on the 

 sound side, and a loop of webbing passed under the arm, in order to 

 provide for counter-extension. The limb is extended by direct traction 

 on the cannon bone or fetlock, whilst the operator endeavours to effect 

 reduction with one hand placed in front and one behind the joint. 



In young animals of trifling weight immobilisation may be attempted, 

 the best method being the application of pitch plasters. If, on the other 

 hand, the subject is heavy, there is so great a chance of displacement 

 when lying down and rising, that such cases are usually sent to the 

 butcher, or abandoned to chance. Pielative recovery, sufficient to permit 

 of growth or fattening, may take place without professional assistance. 



IV.— HYGROMAS. 



Hygromas result from chronic inflammation of serous bursee, naturally 

 existing, or of serous bursae which form at prominent points where the 

 skin is exposed to repeated friction, blows, shocks, or over-extension. 



They usually develop slowly, without producing marked pain or 

 alarming symptoms, and therefore the practitioner is seldom consulted 

 until the swelling has attained a considerable size. 



