Prevalence of malignancy in canine mammary masses in a population of shelter dogs

A retrospective study was carried out on 11 bitches with mammary masses that were surrendered to a municipal shelter in Florida from 2017 to 2019. Ten bitches had reached sexual maturity, and 1 did not have an indicated age. Objective was to determine the prevalence of malignancy of mammary masses in this population. Mammary masses were removed at ovariohysterectomy and submitted to a commercial pathology service for analysis. Ten bitches had solitary mammary masses and 1 had 2 mammary masses. A total of 12 mammary masses were submitted; 11 (92%) had no evidence of malignancy and 1 mass (8%) had low-grade neoplasia. Most common masses identified were adenomas (n = 7). Other masses identified included a parasitic granuloma, follicular cyst, lipoma, and mammary ductal ectasia. One neoplastic mass (grade 1 mammary carcinoma identified) was excised from a 7 year old Chihuahua mix with multiple mammary masses. Three (25%) masses in this patient were not mammary in origin. Chihuahuas and Chihuahua mixes (n = 6) were overrepresented in this study. In this small population, mammary masses were predominantly benign. Further studies are needed with expanded sample size and involving a reproductive pathologist.

Keywords: Mammary, neoplasia, canine, benign, malignant

This manuscript was originally published in the journal Clinical Theriogenology Vol 12(3) Sept 2020.  Clinical Theriogenology is the official journal of the Society for Theriogenology (SFT) and the American College of Theriogenologists (ACT).  This content has been reproduced on the IVIS website with the explicit permission of the SFT/ACT.