Feline Mammary Adenocarcinoma – NAVLE Study Guide

Overview and Clinical Importance

Feline mammary adenocarcinoma is a highly aggressive malignant neoplasm originating from the glandular epithelium of mammary tissue. It represents the third most common tumor type in cats (after lymphoma and skin tumors), accounting for approximately 17% of all feline tumors. Unlike dogs, where approximately 50% of mammary tumors are benign, 80-90% of feline mammary tumors are malignant, with adenocarcinoma being the most common histologic type. This disease predominantly affects older, intact female cats and carries a guarded to poor prognosis due to high metastatic potential.

Epidemiology and Risk Factors

Signalment

Feline mammary tumors typically affect older female cats between 10-12 years of age. While any breed can be affected, Siamese cats have twice the risk of developing mammary carcinoma compared to other breeds and tend to present at a younger age. Domestic shorthair cats are commonly affected due to their prevalence in the general population. Male cats can develop mammary tumors but this is rare and typically associated with exogenous progestin administration.

Hormonal Influence and Protective Effect of Spaying

Hormonal status is the most significant modifiable risk factor. Intact queens have a 7-fold higher risk of developing mammary tumors compared to spayed cats. The protective effect of ovariohysterectomy is age-dependent and diminishes rapidly: