8 July, 1907.] 



Lameness in Horses. 



425 



shock and the providing of an elastic impetus to the elevation of the foot ; 

 and the suspension of these functions is a considerable factor in the causa- 

 tion of navicular disease. In Norway and Sweden this disease is almost 

 unknown and the immunity is ascribed to the fact that in these countries 

 horses are never shod with heels or calkins — as horses working at any 

 pace beyond the walk never should be shod. 



Rheumatism sometimes settles in the navicular bone and causes navi- 

 cular disease. In such cases there is no ulceration of the bone but a 

 porcelainous matter is deposited in it. 



The age period of navicular disease is from five years onwards. 



Symptoms. — As a rule this disease affects only light-bred horses having 

 naturally undersized and narrow or " muley " feet. When the disease 

 is well advanced the heels become contracted or " wired in " and the 

 frog and hoof generally present a shrunken appearance; this, apart from 

 the natural narrowness of the hoof to begin with. 



The most characteristic feature of this form of lameness in the usual 

 run of cases is "pointing" described on page 212. (See Fig. 71.) 

 This sign may be noticed for perhaps months before actual lameness is 

 observed. Pointing is also habitual in lameness from corns but in that 

 case the heels are flat and expanded rather than upright and contracted. 



tu 7'j. -\;Lvicular bones (inferior aspect) showing various stages in 

 the process of ulceration constituting navicular disease. 



The horse may appear to walk sound but lameness is pronounced at the 

 trot. It is most marked when the horse is first moved from the stable in 

 the morning and, unlike the lameness of laminitis or corns, it may dis- 

 appear after he has become warmed up at exercise. When put to a trot 

 the animal goes with a tripping, vet cautious, gait stepping short and on 

 the toes, in consequence of which the toe of the shoe is always the part 

 most worn. The larneness is always more pronounced on hard ground 

 and when the horse is ridden. The horse appears afraid to go down 

 hill, and when doing so the lameness, and the gingerly " cat on hot bricks " 

 style of gait, is very distinct on account of him trving to avoid putting 

 weight on the heels. 



A new mcchanicaL met/iod of detecting navicular disease has recently 

 been practised in France. It is based upon the principle that when the 

 navicular bone is subjected to pressure from the contraction of the tendon 

 passing over it there will be flinching from the pain caused. The horse 

 is made to stand with the suspected foot on a wedge of hard wood, about 



