THE DOG AS A CARRIER OF PARASITES AND DISEASE. 6 
muscular cysticercosis, or so-called "measles," in sheep; muscular 
cysticercosis, or " measles," in reindeer ; cysticercosis of the liver and 
mesenteries in stock ; tapeworm in man, especially in children ; round- 
worm in man; tongueworm in man and stock; and fleas and ticks 
which transfer from the dog to man and which may in this way 
transmit disease and parasites. The above list is sufficient to show 
that the dog is of major importance as a carrier of parasites danger- 
ous to man and domestic animals. An elaboration of the list follows. 
RABIES. 
It has been known for over 2,000 years that what are called mad 
dogs, those affected with the disease termed rabies, hydrophobia, or 
lyssa, could transmit this disease to stock and to man by biting them. 
For 2,000 years the disease has been reported in sporadic and epidemic 
outbreaks. It is now recognized as a widespread, acute, infectious dis- 
ease of the central nervous system, characterized by extreme nervous 
excitability. It is a disease which, if untreated, leads to a certain 
death of the most horrible and agonizing sort. It owes its wide dis- 
tribution and its very existence almost exclusively to the dog. The 
disease may manifest itself in dogs or other animals under the form of 
dumb rabies or furious rabies. In dogs there is commonly evidence of 
depraved appetite, the dog eating sticks, leather, and stones, and the 
finding of such things in the stomach is a suspicious indication of pos- 
sible rabies. There is a partial or complete paralysis of the throat, and 
the resultant difficulty in drinking is the basis of the erroneous idea 
that the mad dog is afraid of water. As a matter of fact, such dogs 
are often very eager for water but are unable to swallow it. The 
disease seems to have some specific effect on the centers controlling 
biting, the feature on which transmission of the disease depends, and 
not only dogs but such animals as the horse show a tendency to bite 
when affected with rabies. The disease is suspected of being due to a 
parasitic protozoan, though as yet too little is known regarding this 
to warrant a definite statement. An examination of the brain of 
rabid animals shows certain cell inclusions known as Negri bodies 
(fig. 1) , the nature of which is not at present well known. 
It has been pointed out in a previous publication x of the United 
States Bureau of Animal Industry that rabies is becoming increas- 
ingly prevalent in the United States. That publication cites the fact 
that the New York Pasteur Institute had treated 1,608 cases of hy- 
drophobia during the first 11 years of its existence, up to 1901. 
The Chicago Pasteur Institute, established at about the same time as 
1 Rabies and its increasing prevalence. By George H. Hart, Bureau of Animal Indus- 
try Circular 129. Washington, 1908. 
