Grease. Seborrhea of the Digital Region. 525 



and giving off a most repulsive odor. Like the preceding erup- 

 tion these grapes may extend around the front and sides of the 

 pastern, and upward beyond the fetlock, but especially behind. 



This advanced condition shows no tendency to spontaneous 

 recovery and the connective tissue and lymphatic plexus becoming 

 involved, the leg often swells to enormous dimensions, from six 

 to twelve inches in diameter at the fetlock. It may last indefi- 

 nitely until the patient is worn out, or it may extend to other 

 organs by contiguity or embolism. Canker of the frog and sole, 

 fistula (quittor), sand crack and seedy toe may be named as 

 complications, also septicaemia or pysemia with abscesses in the 

 lungs, liver, brain or bowels. 



Lesions. In the first stage there is mainly the congestion of 

 the skin extending into the large and numerous hair follicles of 

 the pastern. If pressed, a transparent serum bedews the surface, 

 and if sectioned the follicles around the hair bulb are seen to be 

 distended by a similar product. The hairs are easily pulled out. 

 The subcutaneous connective tissue is filled with a yellowish 

 serosity and at intervals may be seen a red point of vascular 

 stagnation or blocking. Later these products are more abun- 

 dant and those on the now swollen and excoriated surface are 

 distinctly foetid. The infiltrated lymph plexuses in the con- 

 nective tissue are more distended, their walls thickened and con- 

 solidated, and the rigid skin is thus firmly bound to the 

 structures beneath. A careful examination shows the presence 

 of subepidermic vesicles of various sizes. The congestion may 

 extend deep enough to involve the periosteum of the digital bones 

 and the ligaments of the joints. The grapes are each attached 

 by a pedicle from which branch out cauliflower-like, fine pa- 

 pillary processes, that aggregate into a solid cluster. They 

 are very vascular and grow out cluster above cluster until they 

 reach large dimensions. 



Diagnosis from Horse Pox. Since the days of Jenner the 

 claim has been constantly made that grease and horse pox were 

 one and the same. Horse pox is however to be distinguished 

 by its transient course, its inoculability, its incubation of three 

 days, its abundant exudate concreting on the hairs of the pastern 

 as a yellow mass sugestive of crystalline structure, by the red pit 

 in the skin in which this mass is imbedded, by the spontaneous 



