242 Diseases of tJie Skin. 



Animal Parasites of the Skin. — These are included 

 under the term Dermatozoa^ which eaibraces a great 

 variety in the forms of animal Hfe. Their movements 

 are directed in the search for suitable breeding-places, as 

 well as for their natural sustenance, and thus a large 

 amount of tissue is destroyed, accompanied by severe 

 irritation, which induces a form of active inflammation, 

 or true dermatitis. We call the disease mange, as es- 

 pecially the result of the presence of the acarus, or mange 

 insect ; it is, notwithstanding, true inflammation of the 

 skin. Contagion plays the essential part, as true mange 

 cannot exist without the parasite. It may attack the 

 best of animals, but the common subjects are those de- 

 bihtated by want of food and necessary care, whose 

 hunger leads them to prowl, and ferret out from the 

 dirtiest places the wherewith to appease their hunger, and 

 there meet with the acari; or it may be in the company 

 of infected dogs that the disease is contracted. The 

 differences exhibited by various forms of parasitic disease 

 in their potency of contagion, depends on the habits of 

 the acarus. Infection, as we understand it, is not a term 

 of suitability ; the parasite does not become aeriform, 

 nor is it, as far as can be ascertained, carried by the air. 



Scabies, or Mange of the Dog, technically known as 

 Sarcoptic Scabies, is the analogue of " itch " in mankind, 

 and the " scab " of sheep. The producing parasite is 

 the Sarcoptes canis, which usually first invades the parts 

 least disturbed by the feet of the sufferer ; thus we find 

 the back of the neck is the spot where the earliest signs 

 may be looked for. From thence it spreads rapidly, as 

 the army of acari have multiplied by thousands or even 

 millions. Their operations give the subject no rest. He 

 loses his appetite, is depressed, puts on a haggard look, 

 and is feverish. He is continually scratching, and the 

 wildest paroxysms are usually evident after eating, drink- 

 ing, or lying in the warmth of a fire. He enjoys being 

 scratched by the fingers, and places himself suitably for 

 its being continued over the entire body. From this 

 point the disease becomes intensified, as every spot, bed, 

 &c., frequented by the patient, and also the sufferer's 



