LAMENESS AND DISEASES, ETC. 181 



Bog Spavin. — Is a dropsical condition of the joint, which 

 becomes so either from a loss of power in the absorbent vessels, 

 or an increased action of the sacs which secrete the joint oil. 

 Perhaps both these causes may concur in producing the disease, 

 the more remote cause of which is hard work — that is, too great 

 or too long continued action of the joint. 



The bog spavin does not so often occasion lameness as the 

 other, except when a horse is worked hard, which generally 

 causes a temporary lameness, removable by rest ; but it does 

 not always admit of a radical cure, for though blistering is of 

 likely service, the trouble generally returns with any consider- 

 able exertion. Much may be done, however, to assist the horse 

 in his movements, by properly balancing the foot and suitably 

 adjusting the four-calked hind-foot shoe above described, shown 

 in Fig. 145, page 249. 



Canker. — This is a local disease most frequently arising 

 from the thrush, and attacking the front feet. It consists at 

 first of an ulcerous sore in cleft of frog, when the inflammation 

 of the parts is severe and they are quite tender — often making 

 the horse quite lame. The parts afiected become very soft and 

 rotten, with a discharge of purulent matter. By early attention 

 and proper treatment the disease is easily cured, but if it con- 

 tinues its ravages it not infrequently destroys the horny frog 

 and often extends to the sensitive sole and other parts of the 

 foot. The simplest treatment I have found to be the quickest 

 and the best: First, dress the foot, as per Fig. 23, then take 

 three or four old rasps, sharpen one end of each and heat to a 

 white heat, and while in that state apply to cankered part of 

 frog, holding the iron at an angle of about 45 degrees, and giv- 

 ing it a quick downward stroke along the side of frog from 

 upper edge down and forward, and continuing with the other 

 heated irons until bottom of soreness is reached and burnt away. 



