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 hifestation. — 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). 



Synonyin. — Mange mite ; itch mite. 



History. — This species is widely distributed. 



Animal hifested. — The dog. 



Co7iditio7i 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- 



