HORMONAL HISTORY AND CLINICAL EMERGENCE O F MAMMARY-TUMORS IN THE BITCH - AN EPIDEMIOLOGIC-STUDY

A retrospective case/control study was performed in order to evaluate the influence of hormonal history on the risk of mammary tumor develop ment in the dog. We particulary studied the effect of ovariectomy, con traceptive treatments with depo-medroxyprogesterone acetate, pseudopre gnancy and pregnancy. We also evaluated the influence of those paramet ers on the age of detection, the number and the histology of the lesio ns. 405 bitches with mammary tumors and 274 control bitches supported this study. A protective effect of ovariectomy was confirmed. It is st ronger for bitches sterilized early in life but remain significant als o in old bitches. Frequent progestative treatment leads to a slight in crease of the risk but does not significantly influence the number or the histology of the lesions. Frequently treated bitches are affected earlier thant non treated bitches. Pseudopregnancy seems also to incre ase the risk. A similar but not significant tendency is observed in pa rous bitches. We conclude that ovarian hormones and progestagens have a promotor effect on mammary tumor development in dogs either directly or indirectly.