Foot-and-Mouth Disease. 101 



generally passed off, and the pangs of hunger compel the 

 animal to attempt mastication if grass or other soft food is to 

 be had. The tenderness of the feet gradually declines also, 

 and in uncomplicated cases of moderate severity all the visible 

 manifestations of the disease have disappeared within ten or 

 fourteen days after the onset. In young animals, liberally fed, 

 the former good condition is usually rapidly gained after an 

 attack of foot-and-mouth disease ; but complete recovery is 

 much slower in older animals, and particularly in milch cows. 



The symptoms in sheep are generally somewhat different 

 from those just described, inasmuch as in them the mouth 

 lesions are frequently slight, while those of the feet are more 

 constant and severe. Thus, the chief symptom is great lame- 

 ness, associated at the outset with suspension of runiination, 

 refusal of food, and felirile disturbance. The pain in the feet 

 is often so great that the animal is unable to gather its food, 

 and lies persistently, with consequent rapid loss of condition. 

 The lesions in the feet are much aggravated if the sheep be 

 driven long distances on hard roads, and in such circumstances 

 " casting of the hoof " frequently results. 



In pigs, as in sheep, the feet symptoms predominate. The 

 animals lie persistently in their litter, and when forced to move 

 they frequently squeal from the pain in their feet. 



The inability to feed and the slavering which are the con- 

 stant symptoms of foot-and-mouth disease in cattle are caused 

 by the formation of vesicles or blister-like elevations in 

 connection with the lining membrane of the mouth, and the 

 lameness is due to the similar alterations occurring in the feet. 

 In the mouth the vesicles may form on any part of the lining 

 membrane, but they occur most frequently on the inside of the 

 lips, the pad of the upper jaw and the tongue. The vesicles 

 are produced by the escape from the blood vessels of a watery 

 liquid, which accumulates and forces upwards the superficial 

 horny layer of the membrane lining the mouth. The vesicles 

 vary in size from a five shilling piece downwards, and their 

 outline may be circular, oval or irregular. The membrane over 

 these blister-like elevations is soon ruptured under the move- 

 ments of the tongue and lips, the liquid escapes, and the vesicle 

 becomes converted into a shallow sore or ulcer. In uncom- 

 plicated cases the raw sore which is thus left very speedily 

 heals. That is generally true also of the lesions which form 

 about the feet, but in that position the healing process is apt to 

 be retarded by the presence of dirt which almost inevitably 

 gets into the sores. 



Foot-and-mouth disease frequently exhil)its remarkable 

 departures from what may be called its ordinary course. These 

 variations may be in the direction of either increased or 



