52 PARASITOLOGY. 
parasites cause a piling up of scabs, thus producing 
a scabby condition. As the disease progresses the 
scabby patches enlarge and the scabs pile up, until 
they are often half-an inch in thickness, unless the 
parts have been rubbed. 
Symptoms.—Pruritus; will rub against any post, 
fence, stall or other object. Itching is more intense 
at night than during the day, and worse in warm 
weather than in cold; when clothed than when not 
clothed. The parasite first makes its attack in the 
region of the withers and back, and gradually spreads 
over the body. Hairless scabby patches appear in 
later stages. 
Mode of Infestation.—The horse may come in contact 
with infested animals, or be placed in quarters in 
which infested animals have recently been kept; or, 
contact with curry-comb, rub-rag, brush, harness, 
blanket or saddle recently used on infested animals. 
SARCOPTES SCABEI; variety canis (Canis—dog). 
Synonym.—Mange mite; itch mite. 
Hiistory.—This species is widely distributed. 
Animal Intested.—The dog. 
Condition Produced; Symptoms.—It begins first on 
the facial region and ears; then on the breast, feet 
and abdomen, and last on the body. It is not un- 
common to find cases with the entire cuticular sur- 
face affected. The scabs are not allowed to pile up 
as we see on the backs and withers of cattle and 
other large animals, for because of the intense itch- 
ing the animal constantly rubs and scratches itself 
so that we find only thin scabs. The skin becomes 
partially denuded of hair, and in later stages the an- 
