514 DISEASES OF CATTLE, SHEEP, GOATS, ETC. 



1. Lambs often become affected with sore mouths by coming in 

 contact with the infectious principle. Hard, dry scabs, warty in ap- 

 pearance, are produced frequently, covering the entire lips, and 

 which upon being removed leave a raw, granulated surface with or 

 without an exudate of pus. These lesions may be present in lambs 

 before they are weaned, in those that have been weaned, or in lambs 

 which are forced to the range for hard dry feed after being on succu- 

 lent forage. It is not, however, the feed or the pasture or the fact 

 that they have just been weaned which of itself causes the lesions ; 

 but in addition to these predisposing causes, the necrosis bacillus 

 becomes present and the disease continues to spread. 



2. Sheep are sometimes forced to wade through alkali gumbo 

 mud to reach water in the lakes and reservoirs when they become low. 

 This mud becomes matted in the hair and wool of the legs, and 

 becoming dried by the sun and winds may be rubbed off, pulling hair 

 and skin with it, and thus opening the way for the entrance of the 

 necrosis bacillus followed by ulcerations on the legs. 



3. In the winter time the tissues, especially of the legs and 

 sheath, may become devitalized as a result of freezing or of frost 

 bites, thus allowing the necrosis bacillus to gain lodgment and 

 develop. 



4. Injuries in the region of the legs and feet due to thistles, 

 cacti, briars, bruises, etc., and wounds of the lips as a result of pick- 

 ing up harsh forage or frozen forage or in breaking through crusted 

 snow for feed, provide favorable conditions for the entrance of the 

 bacilli. 



The immediate cause of the necrosis is the necrosis bacillus ; the 

 remote cause may be any bacterial agent capable of injuring the mu- 

 cous membrane, or chemical effects connected with the feed any- 

 thing, for that matter, that could produce a catarrhal or eroded con- 

 dition of the intestinal mucosa. 



Lodgment in the tissues of the body of a susceptible animal is 

 all the necrosis bacillus requires. Once this is secured where it may 

 develop and throw out its deadly volatile toxin, all tissues with which 

 it comes in contact become alike a prey to its necrosing action. As 

 a result we may have necroses of the skin, muscle, hoof, cartilage, 

 bones, mucous membrane, navel, and internal organs. 



ECONOMIC IMPORTANCE OF THE DISEASE. 



The importance of this organism is far beyond its relation to 

 lip-and-leg ulceration, since it affects calves, pigs, goats, adult cattle, 

 horses, deer, rabbits, dogs, and chickens, and various forms of necro- 

 bacillosis may occur in these animals on premises contaminated with 

 the infectious principle of this disease. Therefore, as a large ma- 

 jority of species of domestic animals are susceptible to this infection, 

 and as a constant relation may exist between an attack of one form of 

 necrobacillosis and the previous occurrence of another tvpe of the 

 infection in the same or another species of animal, it benooves one 

 to prevent any susceptible animal of whatever species from coming in 

 contact with a diseased one, or with such corrals, sheds, manure, and 

 pastures as might be harborers of the contagion. 



