CUTANEOUS DISEASES DUE TO ANIMAL PARASITES 465 



symptoms of salivation. Insect powder (pyrethrimi), mixed with 

 alcohol, can also be rubbed into the body. 



Ixodes Ricinus. — This parasite, which is about 2 mm. in length, and 

 sometimes when full grown almost 3 mm., looks very much like an 

 acarus. It penetrates into the skin and sucks 

 the blood, and is generally seen in setters or 

 pointers, and dogs when working through the 

 woods and underbrush become filled with them. 

 Turpentine and petroleum will destroy them in- 

 stantly, or, better still, a small quantity of chloro- 

 form or ether sprayed on the skin makes them 

 loosen their hold immediately. They should never 

 be forcibly pulled away from the skin as they leave 



. . . . Fig. 165. — Ixodes ncinus. 



the mandibles m the skm and cause great irrita- The accompanying line is 

 tion and frequently an abscess. ^^'^ natural size of the 



Leptus Autumnalis. — This is what is known 

 as a "harvest bug" or acarus. It is about 4 mm. in length, 

 and is the red larva of thrombidium holosericeum. While human 

 beings are c{uite frequently affected with this parasite, it is only 

 rarely found in the dog. Pustular inflammations of the skin of the 

 dog are sometimes produced by this parasite. The rash was very 

 prominent on the abdomen and the inner fascia of the legs, and was 

 healed quickly by an application of carbolic acid and glycerine, or 

 carbolated cosmoline. 



Dermatophagus Canis. — This is very rarely found in the dog, and is 

 a parasite which affects the ear, producing otitis externa. For further 

 details refer to Parasitic Otitis (page 439). 



CUTANEOUS DISEASES DUE TO ANIMAL PARASITES. 



Sarcoptes Scabiei. 



{Sarcoptic Manyc; Scabies Sarcoptica.) 



Sarcoptic mange (common mange, scab) is a disease of the skin 

 which is very common, particularly where a large number of animals 

 are together. It is accompanied by violent itching, and is due to the 

 presence in the integument of the sarcoptes scabiei squamiferis. 



Description of Sarcoptes Scabiei. — This parasite is about 0.2 to 0.3 mm. 

 broad and from 0.2 to 0.5 mm. long. It has a rounded, turtle-like shape 

 and a horseshoe-shaped head, with well-developed club-shaped scissor- 

 like jaws. It has short rudimentary feet, and tulip-shaped suction cups 

 which are attached to the first, second, and fourth pairs of feet in the 

 male, while in the female they are found in the first and second pairs only. 

 In the back we see six elongated acorn-shaped scales or thorns, and four 

 30 



