230 DISEASES OF BONE. 



have reason to fear that pus is beginning to form either in the bone or 

 immediately underneath the periosteum, we should provide for its free exit 

 by means of the knife, and should treat the wound antiseptically (p. 74). 



The treatment of inflammation of bone is generally best carried out by 

 severe " counter-irritation," such as firing or sharp blistering. The rationale 

 of this practice appears to be that violent local irritation stimulates in- 

 flammation of bone to complete its course. Thus, in spavin it tends to set 

 up bony union between inflamed surfaces of bone which, by pressing against 

 each other, give rise to pain and consequent lameness. In sore shins and 

 apparently in curb, the completion of the inflammatory process seems to 

 leave the bone and its covering membrane (the periosteum) free from any 

 abnormal tenderness. In splints, the removal of pain is no doubt obtained 

 in both ways ; for during their formation there is liability of friction 

 occurring between the inflamed surface of a splint bone and that of the 

 cannon bone. 



Splints. 



DEFINITION. — According to the popular view, a splint (Fig. 

 77) is a bony deposit which appears on the side of the leg, between 

 the knee or hook and fetlock; but following the teaching of 

 Percivall, it would be more correct to say that a splint is a bony 

 deposit which takes place between the cannon bone and one or 

 both of the splint bones. This connection is well shown in Figs. 

 78 and 79, especially when they are compared with Fig. 80, which 

 represents a cannon and splint bone free from splint. 



PREDISPOSITION.— Evolution plays a large part in the 

 formation of splints, which, certainly, were seldom if ever present 

 in the remote five-toed or even three-toed ancestors of the horse. 

 If we compare our own hand to the lower portion of a horse's 

 fore leg, we shall see that our wrist corresponds to his knee, and 

 our middle finger to his pastern and foot. His ancestral digits 

 (fingers or toes) which would correspond to our thumb, index finger, 

 ring finger and little finger, have entirely disappeared during the 

 course of evolution ; and the bones (metacarpal) between the knee 

 and the first digit (thumb) and fifth digit (little finger) have also 

 vanished. The metacarpal bones of his second digit (our index 

 finger) and fourth digit (our ring finger) remain, however, in the 

 more or less decadent state of splint bones. 



Splint bones are sometimes called rudimentary bones, but that 

 is an evident misnomer. 



This diminution in the number of the digits of the horse is 

 due to gradual alteration of surroundings. His early ancestors 

 no doubt found an expansive foot of five, or even three, digits, 

 useful for sustaining the weight of their bodies in the more or 

 less marshy ground which these animals inhabited. But as their 

 descendants adopted harder " going " for feeding and roaming 



