THE IMPROVED ART OF FARRTERY. 287 



healthy state of all animals is constituted by a due and 

 vigorous circulation of the blood, and a regularity in 

 the natural evacuations of the body. Whatever dis- 

 turbs any of these functions will produce debility. In 

 a full plethoric habit the blood-vessels become op- 

 pressed by being overloaded, and are thereby rendered 

 incapable of performing their office. Hence debility 

 ensues ; and the legs being the part most remote from 

 the heart, which is the centre of circulation, become 

 swelled for want of the accustomed absorption. On 

 the other hand the circulation of the blood may also 

 be rendered feeble from the animal being weak and 

 emaciated either from immoderate labour, or from a 

 want of sufficient food. 



The disposition to this disease is also greatly in- 

 creased at particular seasons of the year, such as the 

 spring and autumn, or by want of regular exercise and 

 thorough cleaning. The pavement of the stalls of the 

 stable being on an ascent, and obliging the horse to 

 stand on the stretch, is another very probable cause 

 of the grease. 



In the healthy state of the animal the insensible per- 

 spiration is carried on in a regular manner, as may be 

 ascertained by the glossy appearance of the coat, as 

 well as by the softness and pliability of the skin. On 

 the contrary, when the natural evacuations are sus- 

 pended by disease, the coat is hard and dry, and the 

 skin almost immoveable. 



There are many circumstances which may cause a 

 suspension of the insensible perspiration, but the prin- 

 cipal one arises from a sudden change from heat to 

 cold. This may be produced by the horse standing in 

 the open air whilst in a sweat from exercise ; or it may 

 arise from washing him all over with cold water whilst 

 in that state, or from the still more abominable cus- 



