Are there different types of mammary gland tumors in dogs?
Approximately 50% of mammary gland tumors in dogs are benign (non-cancerous). These tumors include primarily the benign mixed tumor (fibroadenoma), and to a lesser degree simple adenomas and benign mesenchymal (type of cell) tumors (fibroma). These benign tumors may be solitary or occur as multiple primary tumors. They may also coexist with malignant mammary tumors. Most malignant mammary tumors are classified as epithelial (glandular). Solid carcinoma and ductular carcinoma are most common. Inflammatory or anaplastic carcinoma comprises between 5-10% of mammary gland tumors. These are the most difficult to treat as there is generally widespread lymphatic invasion in the overlying skin resulting in marked edema (fluid swelling) and inflammation and they are often associated with local and systemic clotting abnormalities. Mammary gland sarcomas comprise only 3% of mammary gland tumors, but tend to have a high metastatic (spread) rate, primarily to lungs. These tumors include osteosarcom
