Rats have extensive mammary tissue and mammary tumours are one of the most common neoplasms in this species. Majority of these tumours are benign fibroadenomas, with a smaller percentage being carcinomas. Fibroadenomas can grow to a massive size and affect the rat’s mobility and function. Tumour removal is achievable with surgery, however, new tumours can arise as early as a few months later.
Desexing female rats by 7 months of age reduces the risk of mammary tumours by up to 95%. There are mixed opinions about whether desexing adult rats (surgically or chemically) once a mammary tumour develops is protective against future tumour growth. A small study found no difference in subsequent tumour development between deslorelin implanted and control rats following surgical tumour removal. More research is needed to answer these question.
Photo of a rat recovering from a spey.
