Geriatric Medicine: tumors (neoplasms, cancers)


A tumor is an abnormal growth of tissue (neoplasm means new growth).

Benign tumors are those that are likely to remain at the site of their original growth. Malignant tumors (cancers) are neoplastic growths that invade surrounding tissue and travel via blood vessels or lymph channels to other body sites where they start to grow anew. Although cats have a comparatively high incidence of cancer, the likelihood of any tumor occurring increases with age.

Many tumors occur internally where you would not likely be aware of them until they have grown quite large. You should, however, watch carefully for growths in the mouth and on the outside of your cat’s body. On both males and females it is wise to check each mammary gland periodically (e.g., once a month) for new growths. Breast cancer is the third most common tumor in cats, and about 85% of the tumors that occur are malignant. It is seven times more common in unspayed females than in those who have been neutered. Although unspayed females at least ten years old are the most likely to develop breast cancer, all cats are at risk including males and young, spayed females. (Siamese cats have a particularly high incidence of aggressive, malignant breast tumors.)


Since about two thirds of all cats with breast cancer have more than one tumor at the time of diagnosis and the likelihood of surviving the disease decreases as the number and size of the tumors increase, early diagnosis and prompt surgical treatment by removing the affected and surrounding breast tissue is very important. Consult your veterinarian without delay if you feel a growth in your cat’s mammary area.

If you find any kind of tumor in any age cat, it is always best to discuss its removal with a veterinarian. If you don’t feel that you can see a veterinarian, watch the tumor carefully for growth. Some malignant tumors metastasize (spread) while the original tumor is still very small; and for some tumors, such as melanomas, microscopic examination by a pathologist is the only reliable way to differentiate benign from malignant growths.


  1. Abnormal swellings that persist or continue to grow
  2. Sores that do not heal
  3. Weight loss
  4. Loss of appetite
  5. Bleeding or discharge from any body opening
  6. Offensive odor
  7. Difficulty eating or swallowing
  8. Hesitation to exercise or loss of stamina
  9. Persistent lameness or stiffness
  10. Difficulty breathing, urinating, or defecating

Source: The Veterinary Cancer Society