14. 



by sick fowls introduced into healthy flocks. Germs generally are 

 spread throughout a yard by means of the secretions, although these 

 do not always contain the casual organism. The infected fowls are 

 not very much different in their general appearance and condition at 

 the beginning of the disease, and thus they often take food and water 

 for a long time, contaminating the food, troughs and cups. As the 

 germs cannot infect fowls so long as the mucous membranes are intact 

 and healthy, the disease does not spread for a certain length of time, 

 although the germs may be present almost everywhere in the yard. 

 Then comes a change of weather, such as a cold night or the beginning 

 of fall and winter, — and suddenly the infectiousness of the disease 

 is increased and roup spreads rapidly among the birds. Unfavorable 

 weather, which causes colds and other infections of the mucous mem- 

 branes, directly opens the way for infection. But it is possible that 

 the roup bacilli, having infected a number of fowls, may gain so much 

 in virulence as to be capable of entering into the tissues of the fowl 

 without previous colds. Like colds, other circumstances which weaken 

 the constitution of the fowls, such as unsuitable feed or feeding, unhy- 

 gienic yards, bad water supplv, etc., contribute towards the spread of 

 the disease. Once present in a poultry yard, the loup-causing bacilli 

 cannot be got rid of, unless by very careful disinfection ; and this is 

 valueless so long as any of the fowls are diseased ; and, as we have 

 already stated, fowls often remain affected with roup, carrying the 

 germs in a semi-dormant state, for months or years. 



It is possible that just one kind of bacillus, for example, our 

 " roup bacillus," causes an outbreak of roup ; or an outbreak may be 

 caused, as here at the Ontario Agricultural College, by several species. 



Treatment and Preventives. 



As roup is not a specific infectious disease, that is, a disease 

 caused by a single species of germ, it is almost impossible to prepare a 

 preventive or curative serum. Hence this method of treating infec- 

 tious diseases cannot be used in roup ; and besides it would be very 

 costly. 



The germs of roup are not very resistent ; they can easily be 

 destroyed when present in cultures, or somewhere outside the animal ; 

 but in the animal tissue, they are very difficult to kill, because they 

 penetrate into the tissue ; and unless this too is killed, the germs con- 

 tinue living for a long time. 



Roup may be cured by remedies, if the treatment is careful and 

 judicious. Obstinately re-appearing false membranes can be success- 

 fully treated by burning the diseased tissue with a strong acid 

 (hydrochloric acid 50 per cent, to 75 per cent.), or other caustics, such 

 as silver nitrate. If the eyes and nose are attacked, they have to be 

 carefully washed, at least twice a day, with an antiseptic solution, 

 such as 2 per cent, boracic acid in a decoction of chamomile flowers, or 



