THE MITES 115 



possibly also to the horse, but the eruption produced iu such cases dis- 

 appears spontaneously in a few days. 



Follicular Mange of the Hog. — Demodex being more difficult to 

 recognize, its j^resence in the skin of pigs probably occurs more often 

 than is generally supposed. The skin alterations which the follicular 

 mites bring about in these animals is comparativeh' slight and, as a rule, 

 are not such as to perceptibly interfere with general health or growth. 

 The primary seat of invasion is usually the skin about the snout. The 

 lesions may extend to the cheeks and even to the neck and chest, though 

 such spreading of follicular mange in the pig is not often observed. 



Maxge of the Dog 



There are three forms of canine mange, as follows: 



1. Sarcoptic mange, due to Sarcoptes scahiei var. canis. 



2. Follicular mange, due to Demodex folliculorum var. canis. 



3. Auricular mange, due to Otodectes cynotis. 



Sarcoptic Mange of the Dog. — Sarcoptic is considered the most 

 conmion mange affecting the dog. Though it may first appear upon 

 any part of the body, it generally begins about the nmzzle, especially 

 upon the bridge of the nose or, not infrequently, around the eyes, at the 

 base of the ears, or upon the breast. As it spreads the ventral surface, 

 axilla, and thighs become involved, the morbid process extending with 

 such rapidity that by the end of a month it may cover the greater part 

 of the body. 



Symptoms, Course, and Lesions. — In its symptoms, course, and 

 alterations sarcoptic mange of the dog is shnilar to that of the horse. 

 It is first manifested upon thin and unpigmented skin by little red points 

 which are soon converted into papules. These rapidly increase in num- 

 ber and, as they rupture and exude their serous contents, deposit a 

 scaly accumulation upon the skin followed by the formation of yellowish 

 gray crusts. As the disease progresses the denuded skin becomes 

 thickened, wrinkled, and excoriated, the cheeks, neck, and breast 

 especially exhibiting deep folds. The itching, always intense, is much 

 aggravated by an increase in the ])ody tempei-ature, as may be brought 

 about b}' running or warm quarters. 



Where large areas of the body are involved in the disease, emaciation 

 and genei-al debility set in, the animal at times giving off an offensive, 

 mouse-like odor. Finally, if the animal is neglected or treatment is 

 unsuccessful, death will ensue by the end of two or three months from 

 the beginning of the invasion. 



Transmission. — The facts of contagion pertaining to sarcoptic mange 

 of other animals apply to this disease of the dog as well. Young dogs 

 and those debilitated are predisposed to infection, though dogs of any 

 age or condition will supj^ort the sarcopt and readily develop the disease. 



