PARASITES AFFECTING THE SKIN 13 
healthy, well-nourished animals; but in this case the 
natural defences are stronger, and so the disease is com- 
paratively easy to eradicate. 
Sarcoptic mange in horses produces symptoms of great 
skin itching, especially when the animal is exposed to 
sunlight and during the night. Ifthe parts are scratched 
with the fingers, the horse shows symptoms of apprecia- 
Fic, 2.—SarcopTes Egu1: DorsaAL SURFACE. 
tion by smacking the lips together and nodding the head, 
and these signs were formerly considered diagnostic of 
the disease. 
Diagnosis is verified by the discovery of the parasite, 
but as this is merely a matter of chance, and may 
require many hours’ patient searching, it is but seldom 
that the practitioner exceeds a naked-eye diagnosis. 
