986 DISEASES OF THE HOCK. 



described by Furlanetto certainly recovered, but proved permanently 

 lame. 



(c) Fractures of the other bones of the hock are less frequent than 

 those above mentioned, and are either due to kicks, to the animal 

 being run over, or to similar violent mechanical causes, or they appear 

 in connection with sprains and luxations. Thus Rey found dislo- 

 cation of the hock-joint between the scaphoid and cuneiform magnum 

 in a horse which had caught its hoof between railway-metals and 

 had fallen. The external small metatarsal was torn away from 

 the large metatarsal and the cuboid bone crushed. 



Diagnosis is seldom difficult, though the seat of fracture can only 

 be determined by post-mortem examination. There is abnormal 

 mobility of the hock -joint, especially for movements of ad- and ab- 

 duction ; crepitation is often audible. 



The prognosis is generally bad, but depends on the degree of 

 lameness, and is, of course, influenced by the presence or absence of 

 other injuries and the nature of the animal's work. 



II.—LUXATION AND SPRAIN OF THE HOCK-JOINT. 



The strong ligamentous apparatus and the interlocking of the 

 articular surfaces of the astragalus and tibia form so perfect a means 

 of union that luxation of this joint must necessarily be of the rarest 

 occurrence. In horses, it is doubtful if any have been reported, 

 for even Louchard's case appears only to have been a severe strain, 

 probably accompanied by fracture of the malleoli of the tibia or 

 of the astragalus. Stockfleth describes having discovered by post- 

 mortem examination inward luxation of the astragalus in a sheep ; 

 the capsule of the joint was ruptured. He also saw displacement 

 between the astragalus and upper row of small hock bones in a cat 

 which had fallen, hind legs first, from a height ; the metatarsus 

 was thrust outwards. The displacement was immediately reduced, 

 a rubber bandage applied, and the animal recovered. In a rabbit 

 which had also fallen from a height, Stockfleth found displacement 

 of the astragalus. In a horse, which had passed its left hind foot 

 through a hole in a wooden bridge, Haubner discovered rupture 

 of the ligaments connecting the metatarsus and lower row of hock 

 bones. The limb was excessively movable, and showed, at the seat 

 of curb, a depression. Frick saw incomplete outward displacement 

 of the astragalus in a dog ; the lower, inwardly-projecting end of 

 the tibia was supported by a new osseous growth covering the inner 

 surface of the astragalus, 



