CRIB-BITING. 



557 



by horned cattle, and of cribbing by pigs are on record. Mules 

 liave never been known to be att'ected with either form of this 

 vice. 



Aerophagia (air-swallowiiig) is recognised as a nervous disease 

 in human medicine. Cases have been described of neurotic 

 individuals who acquired the power of creating by muscular action 

 negative pressure in the oesophagus and thus sucked air into their 

 stomachs. This condition is known as " air-sucking " and is dis- 

 tinguislied from air-swallowing. The case of one of Barnum's 

 " freaks," who could, by swallowing air, pass rapidly from the 

 appearance of emaciation to corpulency, may also be mentioned. 



Fig. 148. — P'ront view of the incisor teeth of a crib-biter, 30 years 

 old. N.B. — The tu.5hes of the lower jaw are in view, owing to 

 great age. 



NATURE. — It appears that the horse requires practice to 

 successfully accomplish the effort he makes to swallow air when 

 cribbing or windsucking. Hence, as a rule marked flatulent 

 distension of the abdomen is present only in confirmed cases, as a 

 consequence of the action of this vice. When there is no dis- 

 tension, it may be a.ssumed that but little air is swallowed, or that 

 the air taken into the mouth is expelled from it when muscular 

 relaxation occurs after the spasm peculiar to the vice has taken 

 place. Both forms of this vice get worse with age. 



Windsucking, which is much rarer than cribbing, appears to be 

 the more developed form of the two; for its practice is far more 

 frequently followed by flatulent distension than that of crib-biting. 



