The aim of this review is to raise awareness for mammary tumors in rabbits and to report progress in related research. Currently, a standardized tumor classification for rabbits is not available, prognostic factors are unknown and the only treatment option is surgical excision. Studies showed that affected rabbits have a wide age range and are nearly exclusively female or female spayed. Most mammary tumors are carcinomas. These may occur together with non-neoplastic or benign mammary lesions. Frequent microscopic findings are lipid droplets in tumor cells, secretory activity and microscopic heterogeneity. Since carcinomas are often negative for estrogen and progesterone receptors (ER-α/PR), modulation of receptor function will unlikely be beneficial for most rabbits. ER-α and PR status may have prognostic significance, since ER-α- or PR-negative tumors have significantly higher mitotic rates than ER-α- or PR-positive tumors. The frequent secretory activity of rabbit mammary tumors may suggest an influence of prolactin on tumorigenesis. Available data contribute to comparative pathology and are the basis for future molecular studies into the identification of additional prognostic factors and novel therapeutic options. They will also reveal the suitability of the rabbit as a model for certain types of breast cancer in women.
Keywords: Oryctolagus cuniculus; comparative pathology; histopathology; mammary tumor-like lesions; mammary tumors; molecular features; rabbit; review.