9 March, 1908.] Diseases of Farm Animals. 153 



Fracture of the Patella or Stifle-cap.— This is often brought 

 about in the same way as dropped hip. In Australia it is also of common 

 occurrence in steeplechase horses and hunters because of the stiff unyielding 

 nature of the orthodox " post-and-rail " fences they are called upon to 

 jump. Frequently when a bold jumper is tiring he is apt to drag his 

 hindquarters over the top rail, and in doing so, especially if there is much 

 pace on, the violence with which the stifles strike the top rail is sufficient 

 to cause fracture of the patella. The fracture is usually a longi- 

 tudinal one and in some cases recovery takes place without a permanent 

 injury to the joint. Such a fracture is eminently one in which a blister 

 should be made to take the place of splints and bandages — bandaging of 

 the part being an impossibility. The foot on the fractured side should 

 be shod with a " patten " shoe — one with a high toe piece and heels so 

 that by the raising of the limb the stifle joint may be relaxed. 



Broken Leg. — Strictly speaking by the term "broken leg" a fracture 

 of the bone between the stifle and hock joints (the tibia bone) is meant. 

 This bone on its inner aspect lies bare underneath the skin, unprotected 

 by muscular or other covering, and it is consequently very liable to be 

 fractured by the kicks of other horses. Of 1,082 fractures occurring 

 during four years amongst horses in the British Army 189 (or 17^ per 

 cent.) were fractures of the tibia. As previously mentioned the fracture 

 often occurs without displacement on account of the strong character of 

 the fibrous covering (periosteum). In such cases there will be slight lame- 

 ness and a limited swelling may appear in a few days (the provisional 

 callus). Perfect rest should be enjoined and the horse should not be 

 allowed to lie down as displacement is apt to occur when strain is put on 

 the bone in rising. 



Fractured tibia with displacement is a very grave affair it being almost 

 impossible to keep the fractured bones at rest on account of muscular 

 action, the fact that the parts have no muscular or other support, and the 

 weight of the limb below. 



^ The tibia is the most common .seat of " green-stick " fracture, the bone 

 being fractured half way through at the point where the blow is received 

 and then split from this cross fracture in an upward and downward 

 direction (see Fig. 2, page 58). With care in the direction of preventing 

 jerky strain on the bone for a few weeks this variety of fracture heals 

 without much trouble. 



DISLOCATIONS. 



A dislocation is an unnatural and persisting displacement of the tones 

 or parts of bones entering into the formation of a joint, as distinguished 

 from a luxation, which is a partial displacement which is not persistent — • 

 one in which the bones slip back into their natural position at some part of 

 the movement of tne joint. These conditions are very rare in animals. 

 In horses the most common forms are: — Dislocation of the patella, dis- 

 location of the shoulder joint and knuckling over at the fetlock. These 

 conditions have already been dealt with in the Chapter on Lameness (see 

 pages 218, 369, and 470). The dislocation of the hip joint in cattle 

 known as " spaldering " has also been mentioned (page 470). 



Dislocation of the trapezium bone of the knee and of the sesamoid 

 bones behind the fetlock has been met with rather frequently amongst 

 racehorses during recent years by Mr. S. O. Wood, V.S., of Caulfield. 

 The condition is a serious one, and although subject of cure with proper 

 treatment by bandaging, it is seldom that recovery is sufficiently perfect as 

 to admit of racing being resumed. 



