MANGE. 



553 



of mange are sometimes only apparent at the end of four to six 

 weeks ; on the contrary, they may occur at the end of fifteen days. 

 Contamination takes place either by direct contact : immediate, as 

 on pasture or at the stable, etc., or by intermediary agents (litter, 

 blankets, harness, grooming implements, and grooms taking care 

 of the patients). Animals which have not received proper atten- 

 tion to the skin, or are emaciated, weak, and those upon which 

 epidermic exfoliation is abundant, are particularly predisposed to 

 mange. 



The first symptoms produced by acari bites are a punctated 

 redness, pimples, and vesicles, augmentation of the epidermic 

 desquamation, the formation of squamae and scabs. As soon as 

 they appear these lesions are accompanied by an intense pruritus, 

 which becomes unbearable during the night, or under the influence 

 of the solar heat, in hot stables, and after strenuous work ; the 

 animals scratch, rub, and bite themselves on the affected regions ; 

 these mechanical irritations alter considerably the local symptoms, 

 which are determined by the parasite itself : the hairs fall out or 

 break, the wool is flaky and the skin is bloody, a more intense 

 phlegmasia is formed in the derma, it passes into a chronic state, 

 and leads to persistent alterations. 



When the disease reaches its maximum intensity we find the 

 skin moist or bloody, ulcerated, scabby, squamous, thickened and 

 wrinkled, etc. 



As a general rule, the course of mange is essentially chronic. It 

 depends upon numerous circumstances, but especially on the para- 

 site species and its habits. While the symbiotes remain stationed 

 in a very limited cutaneous territory, the sarcoptes and psoroptes 

 often invade the whole surface of the body. The constitution of 

 the skin, the care given to it, the stay of the animals in the stable, 

 the season of the year, etc., all influence the course of the trouble. 

 Its manifestations are aggravated by the heat of summer ; it be- 

 comes attenuated, on the contrary, during the cold season. In 

 well-cared-for and groomed horses (army horses) it may remain 

 benign and localized for a long time ; in the sheep, after shearing, 

 a temporary improvement is regularly noticed because for some 

 time the acari suffer ftom their exposure to the weather. Finally, 

 a large number of agents used in lotions and frictions arrest the 

 extension of most manges, exterminating them by killing the 

 parasites. A spontaneous cure has never been seen ; the remissions 



