Mammary (or breast) tumors are common in female dogs, but rare in male dogs and cats. Surgical removal is recommended for most mammary tumors.
A mammary tumor develops as a result of abnormal replication of the cells that make up the breast tissue. Mammary tumors can be benign (non-cancerous) or.
Spaying can largely reduce a dog's risk of developing breast cancer, especially if the dog is spayed before she has an opportunity to go into.