Uterine tumors are cancers that arise from the uterus. They are most commonly benign, but may also be malignant. Uterine tumors, by definition, only occur in intact female dogs. They are usually seen in middle aged to older pets. These tumors arise from the uterine smooth muscle and epithelial tissues — the tissues that line the internal organs and cavities. Dogs are most affected with leiomyomas, a benign smooth muscle mass of tissue (neoplasm); 85 to 90 percent of uterine tumors are this type. Fortunately, only 10 percent of dogs have the malignant form of leiomyosarcoma.
Usually, the condition is asymptomatic but there are a few signs that dogs with this tumor may display. The signs are
Pyometra (infection, pus in the uterus)
Anorexia (lack of appetite)
Straining to urinate