26 CANINE DISTEMPER 
METHODS OF INFECTION 
. As regards the means by which an animal naturally 
becomes a recipient of the contagium, we may safely 
rule out inoculation, and regard that as almost ex- 
clusively confined to the research laboratory; we are 
thus left with two other methods—namely, inhalation 
and ingestion—and there seems little doubt but that the 
disease is contracted both ways. 
Cases are known in which healthy susceptible dogs 
have accidentally gained access to the food and water of 
a distemper patient, which had undoubtedly been con- 
taminated with infective discharges, and as a result of 
partaking of the meal have contracted the disease. 
This, in addition to the undisputed fact that rubbing the 
nasal or ocular discharge of a diseased animal over the 
lips or nostrils (from which it is licked) of a healthy 
dog will produce distemper in the latter, should be 
sufficient proof that ingestion is a frequent natural 
method of infection. My personal view, however, is 
that the majority of cases of distemper arise through 
inhalation of the contagium, either by droplet infection 
or by aerial infection. 
In the former method, the bacillus or its toxin is con- 
veyed through the atmosphere as, or in, small droplets 
of sputum which have been thrown into the air during 
the act of coughing or sneezing, and which remain 
suspended for some time. By aerial infection, the con- 
tagium is transported through the air by means of small 
dust particles. Distemper can be as easily spread in this 
way as can tuberculosis, through the drying-up and dis- 
semination of sputum, nasal discharges, etc. Blaine said 
in 1851: ‘.. . even being exposed to the air impregnated 
with the exhalations from a distempered dog for a few 
minutes is sufficient for the purpose.” 
