SEVENTH ANNUAL YEAR BOOK— PART X. 479 



strenuous combat were necessary before it was even partially subdued. 

 It was during this period that a sheep raiser of long practical experience, 

 in writing from his home state, Ohio, made the statement that farmers 

 in his part of the country had in times past been seriously troubled by 

 the appearance of stubborn outbreaks of foot-rot among their flocks of 

 sheep. In no case, however, had he been able to discover the spon- 

 taneous appearance of the disease, but with a little persistent inquiry 

 it had been an easy task to trace the origin of each outbreak to the care- 

 less handling of diseased sheep brought from other localities. Since 

 that time the disease has appeared frequently, but its spread has never 

 assumed such alarming proportions, and, owing to a better understanding 

 of the malady, it has been more successfully controlled. 



SYMPTOMS AND LESIONS. 



The first evidence of an attack of foot-rot to attract the attention of 

 the shepherd is a slight lameness, which rapidly becomes more marked. 

 Previous to this, however, there has appeared a moist area just above 

 the horny part of the cleft of the foot, and this has gradually reddened 

 and assumed a feverish, inflamed appearance. It may first become visible 

 either at the front or back part of the cleft, but usually the erosions make 

 their first appearance at the heel. The inflammation rapidly penetrates 

 beneath the horny tissue, while from the ulcerous opening their exudes 

 a thin, purulent fluid. The lameness has increased and the region of the 

 foot above the hoof is becoming swollen and warm to the touch. The 

 exudate from the erosions contains pus cells, bits of destroyed tissues of 

 the foot, and bacteria. It possesses an odor pungent and disagreeable, 

 but at the same time very characteristic. The experienced sheep-man is 

 frequently able to detect the presence of the disease in a flock of sheep, 

 even though it be while making a casual visit to a strange flock, simply 

 by means of the diagnostic and unmistakable odor which arises from 

 the affected feet. This odor is so pathognomonic of the disease that it 

 would reveal the presence of affected sheep to one familiar with the char- 

 acter of the infection, even before noticing the animals. 



The erosion progresses, if no treatment is applied, and there is rapid 

 formation of fistulous passages beneath the horny covering of the foot, 

 while the softer tissues of the interdigital space are gradually becom- 

 ing degenerated and purulent. The invading microorganisms possess 

 marked burrowing propensities, and the result of their activity is that 

 large areas of the hoof become loosened from the sensitive tissues lying 

 beneath. 



The Invasion of the necrotic process may continue until ligaments, 

 tendons, and even the bones are attacked; but before this final stage is 

 reached nature will attempt to repair the damage, and for this purpose 

 the secretion of formative elements in the injured part is greatly in- 

 creased, until there appears a peculiar growth composed of horny ele- 

 ments, dense epithelial cells and granulation tissue. These unsuccessful 

 attempts at renewed development of tissue are termed " fungoid 

 growths," and they have been known to materially hasten the shedding 

 of the horny covering of the foot by their persistent enlargement within 

 the ulcerous channels cut by the advancing infective elements. 



