176 DISEASES OF THE LUNGS. 



All this is owing to the increased power the expiratory 

 muscles — the same as are employed in discharging the 

 faeces — obtain over the retaining power, or sphincter am. 

 And in inveterate cases, so violent and frequent is the em- 

 ployment of this supplemental power, that the sphincter at 

 length becomes, from continual forced dilatation, weakened 

 to that degree that the anus is seen as often open as shut ; 

 nay, sometimes dilated to an enormous extent, exposing to 

 view the interior of the bowel ; the anus itself, from loss of 

 power, advancing and receding with every expiration and 

 inspiration the horse makes. — The skin also indicates the 

 failure of the digestive powers : it becomes harsh and dry, 

 perhaps hidebound ; the coat likewise grows long and rough, 

 and pen-feathered ; all adding to the generally unhealthy 

 aspect of the animal. — " When one lung only is emphyse- 

 matous, or is much more emphysematous than the other, the 

 intercostal spaces become wider, and it yields a clearer sound 

 on percussion. If both sides are afiPected equally, the 

 whole chest yields a very distinct sound, and exhibits a 

 round globular outline, swelling out on both sides ; and this 

 conformation is so remarkable as to render the existence of 

 emphysema evident from simple inspection.'^^ Will this 

 observation, concerning the altered form of the chest, not 

 apply to horses? 



After the fullest investigation of the subject, prac- 

 tically, and after consulting all the best veterinary authori- 

 ties, both British and Continental, I must confess myself 

 forced to come to the conclusion, to counsel my reader still 

 to adhere to the theory, that emphysema of the lung is the 

 pathology of true broken-wind, and that the emphysema is 

 of the interlobular description. To what extent horses are 

 liable to th^t spurious form of emphysema, called vesicular, 

 which consists in dilatation only of the air-cells, and how far 

 the same may tend to induce broken-wind, 1 am not at 

 present, myself, prepared to say: I can only repeat, that 

 Delafond includes both kinds of emphysema in his proximate 

 causes of the disease. That gross and irregular feeding, 

 > Townsend's * Account of Emphysema in Man.' 



