354 
ON THE CONTAGION OF ITCH OR MANGE. 
Contagion of the Mange of the Dog. 
If there be any other animal from which it is said man may 
contract itch, it undoubtedly is the dog. We have frequently 
had occasion to observe patients who have believed themselves 
to have caught the canine mange, and yet we have never dis- 
covered any thing upon them beyond the itch and sarcopte pro- 
per to man. T have seen little red insects upon dogs, in groups, 
firmly attached to their skins. But none of them burrowed un- 
derneath the epidermis ; neither was there any trace whatever 
of furrow or groove. 
I have also seen the same insects upon cats regarded as 
mangy, without being able to discover whence they came. 
Therefore, we may safely conclude, that, so far as the acarus 
is concerned, and touching certain pathognomonic symptoms, 
true mange or itch has not yet been demonstrated as affecting 
dogs. 
Still, the consideration we have given to the subject of con- 
tagion of the mange of the horse and that of the diseases of the 
skin in the dog, has led us to this novel, important, and incon- 
testible conclusion ; which is — that the diseases of the skin in 
animals , caused or not by acarus , frequently give rise upon 
man , as the result of immediate contact , not of itch properly so 
called , but of some other cutaneous affection. 
May, then, acarus of the horse, or any other animal, trans- 
ported in any notable quantity upon the body of man, give 
rise to pruriferous, eczematous or pustulous eruptions 1 We 
hesitate not to answer, “ they may.” Supposing them, in this 
case, to act as a cause of general irritation, still the disease is 
not itch. 
The human itch is a disease sui generis , having changeless 
characters which belong to no other. It has its incubation, its 
preliminaries, its regular advance, its groove , its insecticide treat- 
ment ; and every disease which falls short of these conditions, 
and, above all, which presents no groove, is no longer itch ; and 
if we give the name of itch or mange to any disease of skin 
simply because such name belongs to that of another animal, be 
that disease psora or not, we shall run into arbitrary and con- 
fused opinions, altogether forsaking true science. 
Recueil de Med. Vet., Decemb. 1850. 
[To be continued.] 
