DISEASM OF THE BUBSA MUCOSA. 287 



External Dislocation of the Patella. This accident is very rare. 

 Stockfleth saw but one chronic case in both legs in a small dog. 

 The subject was lively, walked rapidly, but had very flexed ankle- 

 joints, giving him very much the appearance of a weasel. The 

 tarsus appeared thick and uneven ; the patella, which was located 

 in the muscles of the outside, could easily be pushed back into its 

 normal position; but if left, it immediately slipped out of position, 

 and became dislocated again. This was due to the fact that the 

 crest of the joint had disappeared, offering no resistance to dislo- 

 cation. 



Moller states he has seen external dislocation of the patella quite 

 often, especially in Skye-terriers, while Hoffmann believes that an 

 external luxation of the patella in dogs is impossible for anatomical 

 reasons, because of the straight ligaments. The middle one is the 

 only one of any consequence, and for another reason the patella is 

 extremely small 



Other luxations occur in the dog — for instance, in the hip-joint. 

 In this the head of the femur becomes pushed upward after 

 laceration of the capsular ligament, and the joints of the phalanges 

 sometimes become dislocated. These do not possess any special 

 symptoms that may not be easily recognized by the indications 

 stated under Clinical Symptoms of Luxations. 



DISEASE OP THE BURSA MUCOSA. 



Diseases of the mucous capsules which lie under the skin — for 

 instance, in the acromion, olecranon, and at the ankle. These 

 are not of any special importance in the dog, although we occasion- 

 ally see them affected. 



These diseases are developed in the form of circumscribed, fluc- 

 tuating swellings, either caused by hemorrhage, sero-fibrinous or 

 purulent inflammation of the mucous surfaces. These may be caused 

 by blows, jars, or by some other traumatism. The purulent form 

 is generally caused by some injury produced externally. It is easy 

 to recognize these enlarged bursas. We find a large fluctuating 

 swelling, accompanied by acute inflammatory symptoms. There 

 is much pain on pressure, and the fever, when it has been caused 

 by active inflammation and not through hemorrhage, is very acute. 

 Purulent secretions, as a rule, perforate the skin and escape. 



