•228 PRINCIPLES OF VETEKINAET SURGERY 



•cap of the perf qrans will be seen to slip off tlie point of tlie os 

 calcis, as a rule returning to its place as the leg is flexed. 

 ■Swelling is nsnally pronounced, as this injury more frequently 

 follows external traumatisms. 



IV hat is the prognosis of this dislocation 9 



Almost invariably unfavorable, as it is almost impossible 

 ■to retain the dislocated tendon. 



Tendon KTecrosis. 



What are the causes of tendon necrosis ? 



It is the direct result of a purulent tendinitis. 

 Js purulent tendinitis of primary origin in these cases ? 



Not usually, but is the result of purulent cellulitis of 

 some neighboring organ from which the septic process spreads 

 ito the tendon. 



Why do tendons easily undergo necrosis ? 



Because their powers of regeneration and blood supply are 

 limited. 



Which tendon is most frequently exposed to necrosis ? 



The plantar aponeurosis of the flexor pedis perforans of 

 the horse. 



Where does the infection of the plantar aponeu/rosis start 

 from f 



Almost invariably there is at first, as the result of a nail- 

 prick, a purulent cellulitis of the plantar cushion. From here 

 the septic process extends to the navicular bursa and now the 

 termination of the perforans becomes easily involved, as it is, 

 so to speak, bathed in pus, there being a purulent bursitis; 

 the continuous action of the pus producing necrosis of the 

 tendon. 



