134 DISEASES OF THE SKIN. 



Stf(8C0<PTIC M&NGE. 



The sarcoptic mange is an artificial eczema occasioned in the clog by 

 two exciting causes ; one the irritation of an insect infesting the skin 

 ( Sarcoptes Canis) ; the other the scratching of the animal in consequence 

 of its presence. 



This insect, the Acarus, an animal parasite, is maintained by the nour- 

 ishment it draws from the skin. The male acarus is much the smaller, 

 remains in short burrows or vesicles, while the female tunnels the skin in 

 long canals. The course of the latter is to seek a furrow on the surface, then 

 to attach itself, and by means of its jaws penetrate the outer skin or 

 cuticle, until it reaches the deeper and softer layers where it finds its nour- 

 ishment. It continues to burrow, laying one egg after another and 

 blocking up the passage with them. A young acarus is developed from 

 the egg in about two weeks, and the number of eggs one insect lays is 

 near fifty. This production goes on continuously until the female dies, 

 which is generally in three or four months. 



The young acari as soon as developed scamper over the surface, bore 

 quickly beneath, and occasion the most intolerable itching. Around the 

 furrows form first small pimples, which cbange to vesicles and pustules; 

 from them, bloody matter exudes, which dries and produces thick, dark 

 crusts. 



The itching caused by the insects on the surface of the superficial layers 

 of the skin incites scratching ; the furrows are then opened and the acari 

 set free. The original eruption is destroyed, but eczema displaces it, 

 accompanied by the itching and irritation which invariably attends it ; 

 then the disease increases in extent and intensity as it progresses. 



"Diagnosis. —By a careful study of the eruption a diagnosis ought easily 

 to be reached, and less difficulty will be experienced in the earlier than in 

 the later stages. The condition of the animal and manner of attack will 

 weigh somewhat, as eczema more commonly occurs in debilitated sub- 

 jects. If other dogs in the same kennel are similarly affected, it would 

 suggest contagion. 



Vesicles in sarcoptic mange predominate over any other form of erup- 

 tion at first; they occur alone and are not grouped together as in eczema; 

 again they are pointed, not flat or rounded like those of the last named 

 disease. 



After eczema has been produced by scratching, the difficulty of diagnosis 

 is increased, but only slightly so, for new vesicles will constantly appear 

 on previously unaffected skin. 



Treatment.— While the exciting cause of sarcoptic mange is acari, 

 uncJeanliness certainly exerts a predisposing influence, and this fact 



