Cancer in pets is increasingly prevalent, with numerous types affecting both dogs and cats. Some of the most common cancers include lymphoma, which affects white blood cells and is particularly prevalent in cats' digestive systems. Mast cell tumors often appear on a dog's skin but can occur elsewhere, while osteosarcoma, or bone cancer, is particularly painful and common in larger breeds. Squamous cell carcinoma, a cancer of the mouth, and fibrosarcoma, attacking soft tissues, are also notable. Mammary tumors are frequently observed in female pets. Signs can range from weight loss and appetite changes to lumps and difficulty breathing, emphasizing the need for early detection and treatment.