ECZEMA IN THE HORSE. 295 



This chronic eczema produces permanent changes in the skin. The 

 chief consists in more or less abundant cellular infiltration of the corium, 

 especially around the folds ; dilatation of the lymph vessels ; hyper- 

 trophy of the papillae ; and sometimes a fibrous change in the dermis, 

 with atrophy of the glands and hair follicles. The changes, in fact, 

 are those of sclerosis. 



Eczema especially tends to become chronic in parts irritated 

 by harness and in the flexures of the knee, hock, and phalangeal 

 joints. For a long time all transverse cracks in the skin over the 

 flexures of joints were wrongly considered simple accidents, due to 

 physical, chemical, or thermic causes. Undoubtedly many cases are 

 due exclusively to local influences — during cold weather to the action 

 of snow, mud, or water ; but the transverse cracks which develop in these 

 regions and prove so obstinate (mallenders and sallenders) are often 

 eczematous in character. Their aetiology is dominated and their 

 persistence and chronic character explained by some peculiarity in the 

 animal's constitution. Last month you saw in the external clinique a 

 seven-year-old Norman horse which had been ineffectually treated for 

 nearly a year for numerous comparatively superficial cracks under both 

 front pasterns. The choice of applications had certainly not always 

 been happy. Previous to coming here the parts had been dressed with 

 an ointment containing lard, which had formed a layer of decomposing 

 irritant material, contributing in no small measure to the continuance 

 of the disease. We prescribed local antiseptic treatment and internal 

 medication. The horse returned here a few days ago, and you saw 

 that already great improvement had occurred. I have collected a 

 number of similar cases in which success appeared due, in part at least, 

 to internal treatment, a fact which shows how far these attacks are 

 dependent on the general state of health, or on some disturbance of 

 nutrition. 



In the horse cases of essential as well as of symptomatic eczema 

 are seen, but almost all obstinate attacks depend on some disturbance 

 in the general health. 



As I said before in speaking of canine eczema, it is probable that 

 microbes living on the skin, or at least some of them, play a part in pro- 

 ducing certain forms of eczema, though even in " grease " this part is 

 at present ill-defined. 



In the horse certain eczematoid diseases of the foot and lower parts 

 of the limbs are remarkable both for their clinical appearance and 

 obstinate character. Chronic exudative and hypertrophic dermatitis of 

 the pastern — vulgarly known as "grease" — is characterised by a dis- 



