Small Mammals Q&A 03

This question was provided by Manson Publishing as part of the OVAL Project. See more

A two-year-old female intact pet rat develops these two large tumors on her abdomen:

Question	Answer		Article
What is your diagnosis and prognosis?	This is most likely a mammary gland tumor. Mammary tumors are common in rodents. In rats, these tumors are usually benign mammary fibroadenomas. Although metastasis is rare, perform radiographs before surgery. Tumours generally metastasize to regional lymph nodes, abdominal viscera or lungs. During surgical removal of mammary tumors, collect regional lymph nodes to stage the disease. Unless ulcerated or suspected to be malignant, do not remove the skin overlying the tumour. Ligate any blood vessels supplying the tumour. Closure is routine. Use a subcuticular suture pattern or skin staples because rodents frequently chew and may remove the sutures. Use an Elizabethan collar as needed. Prognosis for recovery is good unless there is metastasis.		Link to Article
How does this condition in rats compare with that in mice and guinea pigs?	In mice, mammary tumors are frequently malignant, invasive and difficult to remove. They are associated with infection by the mouse mammary tumor virus. In guinea pigs, about 70% of the mammary gland tumors are benign fibroadenomas and 30% are mammary adenocarcinomas.		[[|Link to Article]]
What would you recommend to prevent the occurrence of these tumours in pet rats?	Ovariohysterectomy at a young age may decrease the incidence of mammary gland tumours and can be recommended to owners of female pet rats.		Link to Article