Relation of Age and Breed to Susceptibility in Leucosis of Fowls.

Abstract

The transmissible avian tumors discovered by Rous and his associates are not transferable to birds other than fowls. The similar tumor of Fujinami, however, has been successfully transmitted to ducklings (Fujinami, Gye). The infectious diseases of fowls caused by a filterable virus, such as fowl pest and fowl pox, are readily transmissible to several species of birds. Leucosis of fowls is, according to Ellermann and Bang, not transmissible to guinea fowls, doves and turkeys. An investigation was undertaken to determine the relative susceptibility of various breeds of fowls to transmissible leucosis and the possibility of transmitting leucosis to birds other than fowls. It was first necessary to determine the influence of age on susceptibility to transmissible leucosis. Three groups of Barred Rock chickens, each containing 6 members, were injected with 0.6 cc. blood of a leucemic fowl. The fowls of one group were about 4 months of age, of the second about one year and of the third over 2 years of age. The result of these inoculations is shown in Table I. This table indicates that older birds are less susceptible to transmissible leucosis than younger birds and that the period of incubation is shorter in the younger birds. All the breeds of the domestic fowls that were tested were susceptible to transmissible leucosis. The fowls used for these tests were 4 to 5 months old and were inoculated intravenously with 0.6 cc. of leucemic blood. Of 6 Barred Rocks, 4 acquired leucosis; of 6 White Leghorns, 4; of 6 Rhode Island Reds, 2; of 6 mixed breed, 2. In another series of inoculations of 6 Bantams, all acquired leucosis. Of the gallinaceous birds, other than domestic fowls, the Guinea fowl was tested and all of the 10 young Guinea fowls that were injected resisted the inoculation. Likewise unsuccessful were the attempts to transmit leucosis to 12 pigeons.