564 



DISEASES OF THE SKIN. 



is of pale color, as if washed ; it may be removed with the greatest 

 ease. The integument is dry, hard, shrivelled, thickened, cracked, 

 creviced ; we often see ulcerations upon it which are produced by 

 rubbings. 



Besides these local alterations we observe a very intense pruritus. 

 It is generally the first symptom which attracts attention. The 

 animals rub themselves against neighboring objects; they roll, bite 

 themselves, and tear out the wool from the affected regions. If 

 they are rubbed they give evident sigus of satisfaction by moving 

 the lips and shaking the head — movements which are altogether 

 peculiar ; they open and close their jaws alternately ; they move 

 their posterior legs and tail, favoring the action of the hand by 

 the position which they take. The pruritus is especially intense 

 when the animals are exposed to the sun or are kept in a hot sheep- 

 fold, after exercise or during the night. Their continually rubbing 

 themselves hastens the falling out of the wool, and produces more 

 or less deep ulcerative lesions of the skin and a diffuse dermatitis. 



When mange becomes generalized the permanent excitement, 

 loss of nutritive fluids, and suppression of appetite and rumination 

 lead gradually to emaciation. As a rule, weak animals die (hydre- 

 mia, cachexia). 



Course. The course of this acariasis is slow but continuous. 

 A more or less marked aOT'avation is observed in the fall and 

 during the winter; some improvement takes place by shearing and 

 washing. The thin skin of animals belonging to improved breeds 

 is much more sensitive to the action of the psoroptes than that of 

 common sheep. 



Diagnosis. This is based upon the following: 1. The existence 

 of a contagious dermatitis in the flock. 2. Persistent itching and 

 particular symptoms observed in certain animals when they are 

 examined. Frictions and scratching, instead of producing relief, 

 very frequently occasion pain ; this fact is often seen when mange 

 is commencing. Let us add that there are shepherds who are 

 clever in hiding pruritus and in misleading the veterinarian, either 

 by tightly squeezing the sheep being examined, or by using certain 

 energetic drugs. 3. The irregularity of the fleece, which is flaky. 

 The condition of the wool, the ease with which it may be torn out, 

 and the existence of depilated surfaces, are so many symptoms 

 which should induce us to suspect mange. 4. The evidence of 

 lesions revealed by a minute examination of the skin. We must 



