PARASITIC DISEASES OF THE SKIN. 



673. Mange or Scab affects the horse, cow, sheep, dog, cat, &c., 

 and also the human being. This troublesome disease is due to the 

 presence of small parasites developed from eggs, which are deposited 

 in vast numbers, on, or in the skin. 



674. These parasites are of three diff"erent families, viz. :— 



ist.— Symbiotes— the parasites that live on the skin. 



2nd.— Dermatodectes— those boring into the skin. 



3rd. — Sarcoptes — those burrowing through the skin. 

 These differ in size and form in the various animals— as may be seen 

 by the illustrations (Plate XXXVII.)-^nd they also differ in a like 

 respect, accordmg to the situation they occupy on the skin of the 

 various animals. Thus, mange must be considered under the three 

 heads :— (i) Superficial, (2) Middle, and (3) Deep-seated. From this fact 

 It may be easily understood how some attacks of mange readily yield 

 to treatment, whilst others verge on the incurable. It is, therefore, 

 necessary to ascertam what class of mange has to be dealt with, before 

 suitable treatment can be adopted. Mange usually attacks the horse 

 in the region of the mane, head, and tail, causing much irritation, and 

 discomfort to the animal, and when the hook-hke appendages on each 

 parasite are considered, it is not a matter for surprise. Symptoms.— 

 The anmial appears dull, and is much inclined to rub the affected 

 parts, whenever it has the chance. Rubbing the fingers gently over 

 the irritated places causes the animal to move the lips and muzzle 

 with an expression of great pleasure. Close examination also shows 

 a number of small papules containing a small quantity of serous fluid, 

 which soon escapes, forming a scab or crust. 



675. Treatment.— All animals aff^ected with mange should be 

 carefully isolated, since— as will be quite obvious to all, from its 

 parasitic nature— the disease is a highly contagious one. The animal 

 must be carefully washed with some parasiticide. Any of the 

 non-poisonous dips may be used, but dip containing arsenic must not, 

 on any account, be used where the skin is at all excoriated or broken! 



