– Skin tumors are very common in older dogs, but much less common in cats. Most skin tumors in cats are malignant, but in dogs they are often benign. Your veterinarian should examine all skin tumors in a dog or cat to determine if any are malignant.
Mammary Gland (Breast) – 50% of all breast tumors in dogs and greater than 85% of all breast tumors in cats are malignant. Spaying your female pet before 12 months of age will greatly reduce the risk of mammary gland cancer.
Head & Neck – Neoplasia of the mouth is common in dogs and less common in cats. Signs to watch for are a mass or tumor on the gums, bleeding, odor, or difficulty eating. Since many swellings are malignant, early, aggressive treatment is essential. Neoplasia may also develop inside the nose of both cats and dogs. Bleeding from the nose, breathing difficulty, or facial swelling are signs that may indicate neoplasia and should be checked by your veterinarian.
Lymphoma – Lymphoma is a common form of neoplasia in dogs and cats. It is characterized by enlargement of one or many lymph nodes in the body. A contagious feline leukemia virus can be the cause of lymphoma in some cats.
Testicles – Testicular tumors are rare in cats and common in dogs, especially those with retained testicles (testicles that did not move to their normal positions during growth, and may be located in the abdomen or between the abdomen and scrotum).
Abdominal Tumors – Tumors inside the abdomen are common but it is difficult to make an early diagnosis. Weight loss or abdominal swelling are signs of these tumors.
Bone – Bone tumors are most often seen in large breed dogs and dogs older than seven years, and rarely in cats. The leg bones, near joints, are the most common sites. Persistent pain, lameness, and swelling in the affected area are common signs of the disease.
Information found on fetchacure.com