LUXATION OF THE FETLOCK JOINT 105 



surface of the metacarpal bone projects forwards beyond the surface 

 of the first phalanx. 



The condition may be due simply to a habit or vice on the part of the 

 animal to hold its limb so. In other cases it is due to congenital mal- 

 formation of the tendons of the superficial and deep flexors of the digit ; 

 tendons which are apparently too short to permit of the normal disposi- 

 tion of the axes of the bones forming the joint. The result is that the 

 distal extremity of the metacarpal bone is pressed forwards out of position, 

 and so the tension on the tendons is eased. These cases are treated 

 by trimming the foot and improving its shape. The fetlock is then 

 forcibly extended, and maintained in a condition of extension by the 

 application of splints. Plastic bandages are also frequently applied with 

 the same object. 



Acquired knuckling may be due to a variety of causes. It may occur 

 as a symptom of ulcerated heel, or it may be due to the presence of a 

 ringbone which encroaches upon the posterior part of the pastern joint 

 when the suffraginis is carried in a more upright position, with the result 

 that the metacarpal bone is thrown forwards. Knuckling also occurs 

 in some cases of chronic windgall. In these cases the metacarpal bone 

 is thrown forwards to provide a greater area for the accommodation of the 

 gall between the suspensory ligament and the bone. Rheumatic affec- 

 tions of the flexor muscles or the sheaths of their tendons may also be 

 accompanied by knuckling, and very frequently it is the result of chronic 

 sprain of the flexor tendons, which is followed by their becoming shorter 

 and thicker, and causes knuckling in a manner similar to that described 

 in dealing with tendons which are congenitally too short. 



Treatment of acquired knuckling should thus be directed against the 

 cause. If knuckling should be due to some affection of the foot the 

 affection should be treated, and as this heals the animal will cease to 

 knuckle. 



Splints and bandages are also utilised to extend the joint forcibly as in 

 congenital malformation. 



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