FOURTEENTH ANNUAL YEAR BOOK— PART X. 729 



in this manner the head should be well anointed with pure vaseline or 

 with camphorated vaseline. 



The treatment of sick birds requires much time and patience, and 

 there is always the risk that they may carry the contagion for sev- 

 eral months after they are apparently well. Prevention is therefore 

 much more profitable. To accomplish this, measures should be contin- 

 ually enforced which wall exclude contagion of all kinds. New birds 

 and those which have been to exhibitions should be isolated and kept 

 under observation for two weeks before they are put with the flock, 

 and all animals and wild birds excluded, so far as possible. The houses 

 should be kept clean and dry and occasionally disinfected. If the disease 

 appears notwithstanding these precautions, isolate the affected fowls 

 at once at a distance from the well ones, and apply disinfectants freely 

 about the houses and runs. Also place sufficient permanganate of pot- 

 ash in all drinking water to give the latter a deep red color. If the 

 disease proves of a severe type, it is often better to kill the entire 

 flock, and after a thorough cleaning and disinfection of the premises 

 to begin with new birds. This radical method avoids the retention of 

 birds which may harbor the contagion and cause the development of 

 subsequent outbreaks. 



DIPHTHERIA. 



Diphtheria is a disease having some of the symptoms of a cold, or 

 of the contagious catarrh described above, but which differs from these 

 and is especially characterized by the development of false membranes 

 on the mucous surface of the nostrils, eyes, mouth, throat, and even 

 of the smaller air tubes. The false membranes are new growth of a 

 grayish or yellowish color, very tough, and difficult to remove from the 

 tissues beneath them. 



Causation. — The diptheria of fowls is caused by a filterable and in- 

 visible virus, and therefore is entirely distinct from the diptheria of 

 children, which is caused by a well-known bacillus. The disease is strict- 

 ly contagious, and probably never develops as the result of exposure to 

 cold and dampness, although these conditions favor its spread and tend 

 to increase its malignancy. The contagion is generally introduced by 

 newly purchased birds or by birds which have been to exhibitions and 

 there exposed to sick fowls. Sometimes it is carried by pigeons and other 

 small birds. Very often an outbreak is caused by contagion from an ap- 

 parently well bird which had the disease and recovered months before. 



The contagion is spread through the mucus which escapes from the 

 nostrils, or that which is forced out in the acts of sneezing or cough- 

 ing, in the saliva, the secretions of the eyes, and also the excrement. 

 When the disease appears in a flock the floors of the houses, the drink- 

 ing cups, and feeding troughs are at once infected by the diseased birds, 

 and the well ones soon contract the disease from the contaminated water 

 and food. It is consequently but a few days before a large part of the 

 flock shows symptoms, though some are much more severely affected 

 than others. 



Symptoms. — Diphtheria begins as a local irritation or inflammation at 

 some point on the internal surface of the mouth, throat, nostril, or eyes. 



