556 



DISEASES OF THE SKIN. 



cresol, carbolic acid, creosote, tar, petroleum, benzol, fetid animal 

 oil, and essences (essence of turpentine, etc.) The most energetic, 

 but also the most dangerous, are tobacco in infusion or decoction, 

 arsenic, and mercurial preparations. 



Concerning the preparation and composition of these agents and 

 of the medicated baths which are used in the different species, we 

 refer the reader to the study of manges in particular. We will 

 only mention here general facts, which may serve as a guide in the 

 treatment of acariases. 



1. The prophylaxis includes the isolation and seclusion of mangy 

 animals. During the time of treatment we should prevent any 

 immediate contact of diseased animals with healthy subjects, and 

 avoid mediate contagion — through blankets, grooming implements, 

 litter, and the walls of the stable or kennel. Besides, we must 

 disinfect the stables and utensils used in it. 



2. The use of therapeutic agents ought to be preceded by a care- 

 ful cleaning of the skin ; this should be cleared of the scabs and 

 epidermic desquamations, 



3. In selecting an anti-psoroptic we should take into considéra- 

 tion the species, the constitution of the subjects, the condition of 

 the skin, the wounds existing upon its surface, etc. In weak 

 animals it is proper to use only harmless drugs ; we must avoid 

 mercurial preparations for the ox or carbolic acid for the cat. In 

 the sheep, immediately after shearing, the skin is strewn with a 

 number of small wounds and the cutaneous absorption is rendered 

 very active; at this time irritating agents and toxic baths are 

 absolutely counter-indicated. 



4. The treatment must be particularly energetic upon the local- 

 ities where mange is intense; but in the sheep especially it is 

 essential to treat the parts adjoining the diseased surfaces and even 

 the entire skin, for any region may be the seat of a recent infec- 

 tion. 



5. It must be renewed after some time. Very often a first anti- 

 psoroptic application only reaches the acari ; it does not affect the 

 vitality of the eggs, and in less than a week these latter give birth 

 to new parasites. In quite a number of cases, especially when 

 mange is old and stubborn, it is necessary to make a third applica- 

 tion : the eggs being unequally advanced in their development, 

 some of them may have escaped the two former treatments. And 

 in old sarcoptic mange, when the acari have penetrated deeply into 



