DISExiSES OF THE HORSE. 443 



of the skin with points in which the diseased product has become soft- 

 ened like cheese. 



The apparent subsidence of the disease in winter is attributed to the 

 coldness and comparative bloodlessness of the skin, whereas in sum- 

 mer, with high temperature, active circulation, and rapid cell growth, 

 inflammation is increased, itching follows, and from the animal rub- 

 bing the part the irritation is persistentlj^ increased. The hotter the 

 climate the more troublesome the disease. 



The life histor}^ of the parasite is unknown, ])ut it probably enters 

 the system with the food or water. 



Treatment consists, first, in placing the animal in a cool place and 

 showering the surface with cold water. The parasite m^y be destro^^ed 

 hj rubbing the surface of the wound with iodoform and covering it 

 with a layer of collodion, and repeating the applications e^-ery twenty- 

 four hours for fifteen daj's, or until the sores heal up. Ether or chlo- 

 roform may bo used in place of iodoform, being poured on cotton 

 wool and applied to the sore for two minutes before painting it with 

 collodion. 



CRACKED HEELS (SCRATCHES, OR CHAPS ON KNEE AND HOCK). 



This usuall}' sets in with swelling, heat, and tenderness of the hollow 

 of the heel, with erections of the hairs and redness (in white skins), 

 with stiif ness and lameness, which may be extreme in irritable horses. 

 Soon slight cracks appear transversely, and ma}" gain in depth and 

 width, and may even suppurate. More frequent!}^ they become cov- 

 ered at the edges or throughout by firm incrustations resulting from 

 the dr3^ing of the liquids thrown out, and the skin becomes increasingly 

 thick and rigid. A similar condition occurs behind the knee and in 

 front of the hock (raalanders and salanders), and may extend from 

 these points to the hoof, virtually incasing that side of the limb in a 

 permanent incrusting sheath. 



Causes. — Besides a heavy lymphatic constitution, which predisposes 

 to this affection, the causes are overfeeding on grain, unwholesome 

 fodder, close, hot, dirt}^ stables, constant contact with dung and urine 

 and their emanations, working in deep, irritant mud; above all, in 

 limestone districts, irritation hy dry limestone or sandy dust in dry 

 weather on dirt roads, also cold drafts, snow and freezing mud, washing 

 the legs with caustic soap, wrapping the wet legs in thick woolen 

 bandages which soak the skin and render it sensitive when exposed 

 next day, clipping the heels, weak heart and circulation, natural or 

 supervening on overwork, imperfect nourishment, impure air, lack of 

 sunshine, chronic, exhausting, or debilitating diseases, or functional or 

 structural diseases of the heart, liver, or kidneys. These last induce 

 dropsical swelling of the limbs (stocking), w'eaken the parts,.and induce 

 cracking. Finally the cicatrix of a preexisting crack, v/eak, rigid. 



