Anne Gogny, Olivier Albaric, Francis Fiéni

A 3 year-old female rat was presented for the exploration of vulvar and mammary gland masses, observed several weeks ago. The vulvar mass was ulcerated, and was affecting the vagina and a portion of the urethra. The two masses were surgically excised.

A second vaginal mass was identified during surgery, as well as the uterine tumour. All the masses were removed, except a small portion of the first vaginal mass that was left in place, to avoid causing important damage to the urethra. According to the histopathological findings, the mammary gland mass was a fibroadenoma, whereas the uterine and the vaginal tumour were described as a multicentric genital sarcoma. Three weeks later, the remnant tumoral tissue has developed again, and euthanasia was decided.

The prevalence of spontaneous tumours in older female rats (>2 years-old) is 87 percent. Mammary gland tumours (out of which most of them benign), are the most frequent. Uterine tumours are described in rats, but sarcomas are not common.

The size of the rat limits complementary examinations that can be performed. Treatment is also limited by the difficulties of identifying the nature of the tumor prior to surgery.

Nontheless, mastectomy, easy to perform in this species, stays a justified procedure related to the discomfort of the animal due to the volume of the tumor.

This case is a good illustration of the necessity to evaluate pros and cons of the utility of a heavy treatment in species with a short lifespan.