CHAPTER XXI 
TUMORS IN FOWLS 
Tumors in fowls hardly constitute a serious economic problem. 
However, in view of their great similarity in structure to those of 
man, they have received considerable attention. 
FREQUENCY OF OCCURRENCE OF TUMORS 
Curtis has reported upon the frequency of occurrence of tumors 
of fowls based upon autopsies of 880 birds. Of these 79, or 8:96 
per cent had tumors. This percentage corresponds to 90 cases of 
tumors per 1000 birds. No significant difference was noted in fre- 
quency of occurrence of tumors, between birds which died from nat- 
ural causes, and apparently normal birds which were killed. There 
is a significant correlation between age and the occurrence of tumors. 
Of the birds under 2% years of age, only 7.37 per cent had tumors, 
while they were present in 19.17 per cent of birds over that age. 
In birds which died from natural causes, and showed tumors, these 
were directly or indirectly the cause of death in from one-third to 
one-half the cases. There was a decided tendency for the associa- 
tion of hypertrophy of the liver, spleen or kidney, with the presence 
of tumors in other organs. The hypertrophy was apparently due to 
cell infiltration. Death often resulted from internal hemorrhage 
originating in the tumor, the underlying tissue or the hypertrophied 
liver or spleen. Data as to the character of the tumors were classi- 
fied with reference to whether the tumors were cystic or of solid 
tissue structure. Those of cystic structure comprised 22.78 per 
cent and solid tumors constituted 74.68 per cent. Three cases fell 
in both classifications in that cysts were attached to solid tissue 
tumors. In females the genital organs were most frequently in- 
volved. In 37.76 per cent of all, the tumors were in the ovary and 
18.36 per cent involved the oviduct and oviduct ligament. Too 
few males were examined to warrant drawing conclusions. In most 
cases the tumors were confined to one organ. In 15 cases metastasis 
had evidently occurred since tumors of similar nature were found 
in from two to four organs. 
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