THE DOG AS A OABBIEE OF PAEASITES AND DISEASE. 



21 



Fig. 13. — American dog tick (Der- 

 macentor variaMUs) ; male, dor- 

 sal view. (From Hooker, 

 Bisliopp, and Wood, Bureau of 

 Entomology.) 



take no care of them. Under proper conditions of restraint dogs 

 may be rid of fleas and kept free from them. 



Ticks. — In this country the dog is known to be the usual or occa- 

 sional- carrier of 11 species of ticks, almost all of which are also 

 occasib<f>nal or habitual parasites of man 

 or stock. In this way the dog serves 

 the tick by furnishing it with nourish- 

 ment 3.and also aids in spreading in- 

 festation, conveying ticks in this way 

 to man much more effectively than 

 other animals are able to do, for the 

 reason that there is no other animal 

 in such close contact with man, with 

 so many liberties, and with such a wide 

 and unrestrained range during the 

 periods when it is not with its owner. 

 These habits of the dog make it an 

 object of suspicion in connection with 

 tick-eradication work. Such ticks as 

 Vermacentor variabilis (fig. 13), which are common on the dog, are 

 brought into houses rather frequently and have many opportunities 

 to attack man. Such ticks as the spotted-fever tick, known as Ber- 

 macentor andersoni or Dermacentor venustus (fig. 14), are seldom 



found on dogs, but in view of the 

 fact that the bite of one tick may 

 result in spotted fever and the death 

 of the person bitten, even such in- 

 frequent transmission by dogs must 

 be guarded against. This tick is 

 known to occur in Montana, Wyo- 

 ming, Colorado, New Mexico, and 

 the States west of these, with the 

 exception of Arizona. Spotted fever 

 is knoWn to occur in a number of 

 these States, and with the tick pres- 

 ent its occurrence and spread in the 

 other States depend merely on the 

 chance of a carrier of some sort com- 

 ing into them under conditions which 

 will permit of the tick having access to the carrier and to other ani- 

 mals or persons. Dogs may also carry the Texas-fever tick {Mar- 

 garofus annulatus) , and some species of ticks possibly depend on the 

 dog for their continued existence. 



Pig., 14. — Rocky Mountain spotted- 

 fever tick (Dermacentor ander- 

 soni, or D. venustus) ; male, dor- 

 sal view. (From Hooker, Bishopp, 

 and Wood, Bureau of Entomology.) 



