THE DOG AS A CARRIER OF PARASITES AND DISEASE. 
21 
Fig. 13. — American dog tick (Der- 
macentor variabilis) ; male, dor- 
sal view. (From Hooker, 
Bishopp, 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 
occasional or habitual parasites of man 
or stock. In this way the dog serves 
the tick by furnishing it with nourish- 
ment 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 
Dermacentor 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 Der- 
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- 
gar opus annidatus), and some species of ticks possibly depend on the 
dog for their continued existence. 
Fig. 14. — Rocky Mountain spotted- 
fever tick (Dermacentor ander- 
soni, or D. venustus) ; male, dor- 
sal view. (From Hooker, Bishopp, 
and Wood, Bureau of Entomology.) 
