384 DISEASES OF THE HOKSE'S FOOT 



in connection with punctured foot. It occurs, too, as a com- 

 plication in suppurating corn, in severe tread, in complicated 

 sand-crack, as a result of the spread of suppurative matter 

 in acute coronitis, and in sub-horny quittor. 



In ordinary cases of suppurative periostitis the pus formed 

 is yellow in colour, creamy thick, and free from pronounced 

 odour — the so-called * laudable ' pus of the older writers. 

 It so happens in many cases of foot trouble, however, that 

 putrefactive organisms gain entrance side by side with those 

 of pus. In this case the characters of the discharge are 

 very different. It is distinctly more fluid, is of a i^ink or 

 even light chocolate colour, and extremely ofl'ensive. In 

 these instances the pus shows a marked tendency to spread, 

 strips the periosteum from the bone, perforates the outer 

 layer of the membrane, and finally infiltrates the sur- 

 rounding tissues. 



This forms a near approach to what is known in human 

 surgery as an infective periostitis, and in our subjects is 

 nearly always met with in cases of severe prick. Its rapidly 

 spreading character makes it always a dangerous condition, 

 and a punctured foot exuding a discharge of this nature 

 should always be regarded as serious. The close contiguity 

 of the joint (it can never be far distant in foot cases), the 

 spreading character of the disease, and the rapidity with 

 which the horse succumbs to arthritis, are all factors to be 

 taken into consideration, and to lead to a warning-note being 

 struck when attending a case of such kind. 



A further instance of infective periostitis is that met with 

 in acute laminitis. The discharge obtained from the sole in 

 these cases very often bears the character we have just 

 described, and when one considers the thinness of the 

 keratogenous membrane, one is bound to admit that changes 

 so grave occurring in it cannot fail to spread and infect the 

 periosteum. 



(c) Osteoplastic Periostitis. — This is more particularly a 

 chronic process, and is, as the suffix 'plastic' indicates, 

 associated with bone-forming changes in the membrane. 

 It may occur as a consequence of slight but continued 



