242 Diseases of Poultry 



blood, fresh from under a nodule or a diphtheritic exudate, 

 has failed to produce positive infective results. I have also 

 tested it on pigeons with like negative results. 



"The exudates on the mucous membrane of the throat, 

 mouth or larynx appear to be very much alike in all forms of 

 the disease." 



The period of incubation is said to vary all the way from 

 2 to 20 days. Cary reports a case in which a newly pur- 

 chased Barred Plymouth Rock cockerel was placed in the 

 pen with chickens just recovering from the disease. In 24 

 hours this bird had developed a well marked case of sore- 

 head on the wattles, comb, and eyelids. Apparently the 

 period of incubation varies with the mode of transmission, 

 virulency of the virus, the weather (rapid in damp, warm 

 weather and slower in cool and dry weather), and the age and 

 condition of the chicken or pigeon. Chicks from broiling 

 size up to 7 or 8 months old seem to be most susceptible. 

 Chickens with large combs seem to be more susceptible than 

 birds with small combs and wattles. 



Treatment. — The introduction of diseased birds into 

 healthy flocks should be avoided. The same precautions 

 should be practiced in the isolation of sick birds and dis- 

 infecting the houses as is advised for roup (p. 161). When 

 the disease is localized a small amount of individual treat- 

 ment cures many cases. The crust or nodules should be 

 removed and the places treated with creolin (2 per cent 

 solution) or corrosive sublimate (i(j\57) (p. 54) and dusted 

 with iodoform. The iodoform may be put into the eye. 

 When the disease is not far advanced one such treatment 

 may be followed by daily greasing with the ointment rec- 

 ommended on p. 55 or with vaseline or lard. In bad cases 

 the iodoform should be used daily for a' few days and then the 

 ointment. 



Recently some work has been done on the production of 



