Factors Influencing the Occurrence of the Malignant and Benign Canine Mammary Tumors.

Abstract : A case control study was used to determine the relationship between the effects of estrus, parity, pseudocyesis, abortion, estrus prevention, and estrus irregularities upon the expression of the benign and malignant forms of the canine mammary tumors. This study showed that estrus had a more profound influence on the occurrence of the benign than the malignant form of canine mammary tumor, for animals which were neutered experienced 55% of the risk of a benign tumor than their malignant counterpart (P.025). The ability of estrus to set the risk of benign tumor expression seems to be exhibited even after the animal is past the age of maturity. Pregnancy before maturity and pseudocyesis seem to have a subtle effect on the expression of the benign neoplasm through the stimulation of the mixed mammary tumor. Abortion, estrus prevention, and estrus irregularity did not seem to influence either benign or malignant tumors. The factors examined in this study had no predictive value for determining the age at which the neoplasm was expressed. (Author)