Dog cancer refers to the presence of malignant tumors in dogs, which can develop in various parts of the body, including organs, bones, and skin. Common types of dog cancer include lymphoma, osteosarcoma, and mast cell tumors. Symptoms may vary but often include weight loss, lethargy, and unusual lumps or swelling. Diagnosis typically involves veterinary examinations, imaging tests, and biopsies. Treatment options may include surgery, chemotherapy, and radiation therapy, depending on the type and stage of cancer. Early detection is crucial for improving outcomes and enhancing the quality of life for affected dogs.