Contagious Foot Rot in Sheep and Cattle. 105 



mud, sand, or other irritant tends to inflammation. The occur- 

 rence of a local phlegmon, or boil in the region of the foot, an at- 

 tack of aphthous fever, or the inflammation or gangrene caused 

 by ergot or smut may prove the starting point for the coloniza- 

 tion by the Bacillus necrophorus. Indeed any breach of surface 

 or enfeeblement of the tissues may become the efii'cient accessory 

 etiological factor. 



Symptoms and Morbid Anatomy. Since the disease is a slow 

 and chronic one an infected flock usually presents, side by side, 

 cases which show the earliest and the most advanced stages, to- 

 gether with many intermediate grades. At first there is a slight 

 halting or lameness, and examination of the inflamed point, 

 usually the arch of the interdigital space, shows a circumscribed 

 redness and swelling and a moist condition of the affected surface. 

 Commonly the case is further advanced, the greater part of the 

 interdigital space has become involved, the epidermis has fallen 

 off or is being shed in white or yellowish white layers, and a raw 

 ulcerous surface is exposed. As the ulceration advances, being 

 hemmed in by the unyielding horn, it extends beneath it in 

 different directions loosening and detaching it from the vascular 

 parts beneath, and also extending inward into the subcorneous 

 tissues as far it may be as into the tendons, bones and joint 

 structures. The inflammatory exudation may lead to excessive 

 swelling, but mingled with this is the necrotic process which 

 hollows out deep excavations in the tumefied mass. The raw 

 surface exudes abundance of a whitish, opaque fluid of a strong 

 offensive odor, which will penetrate to all parts of the building 

 or pen. This fluid contains abundance of pus cells, fragments 

 of the ulcerating and necrotic tissue, and bacteria of many kinds 

 but including the specific microbe. 



The morbid process may begin at the posterior part of the 

 interdigital space, at the front, or in the median part, in the pad, 

 in the sole, or on the coronet, and it has been named accordingly. 

 As it becomes chronic the hoof may be shed, and in bad cases 

 even the pedal bone, or short of this the joints may be anchylosed, 

 but not infrequently the plastic process acquires the predominance, 

 and large masses of new inflammatory tissue form at the coronet 

 in front, at the heel behind, in the interdigital space pushing the 

 hoofs wide apart, or elsewhere where the morbid process has been 



