Cancer is seen in domestic animals, wildlife, people,
and plants. Cancer is a group of diseases characterized
by uncontrolled growth and spread of abnormal cells.
Veterinarians are trained to use the term neoplasm for
uncontrolled growth of cells. Use of different
nomenclature can lead to confusion even among various
health professionals. Veterinary cancers are
increasingly described in the same “language” as their
human counterparts. If the spread of cancer cells is not
controlled, it can result in death.
Cancer is caused by both external factors (chemicals,
radiation, and infectious organisms) and internal
factors (inherited mutations, hormones, immune
conditions, and mutations that occur from metabolism).
Cancer is treated with surgery, radiation, chemotherapy,
hormone therapy, biological therapy, and targeted
The spectrum of cancers seen in domestic animals is as
diverse as that seen in human patients. For example,
breast or mammary cancer is common in people and also
seen in animals. But spaying at an early age
reduces the chances of mammary cancer in pets.
Experts estimate that one in eight women alive today
will get breast cancer. The vast majority of breast
cancer in cats is malignant while in dogs less than half
All breeds of dogs develop cancer. But some breeds that
have a higher incidence of cancer. For example,
Rottweilers and Greyhounds have more bone cancer, Golden
retrievers develop more cancer of the lymph nodes and
Scottish terriers have more bladder cancer. Similarly
the types and frequencies of various cancers in people
vary by race.
Age and Cancer
The risk of cancer increases with age and most cases
occur in adults who are middle-aged or older. It is
estimated that one in four dogs greater than two years
old will die of cancer. Certain very popular
breeds are over-represented in terms of cancer incidence
The improved general health of pets has resulted in an
increase in age-related diseases, including cancer.
People see a comparable increase with age. About 77% of
all cancers are diagnosed in persons 55 and older.
Early rodent studies
Many initial cancer studies involved rodents. However,
they often did not adequately represent many of the
features that define human cancer. Naturally occurring
tumors in dogs and other animals have clinical and
biological similarities to human cancers that are
difficult to replicate in other model systems.
Pets with cancer could provide crucial insights into the
human forms of the disease, potentially leading to
better treatments and screening for tumors.
Investigators at the U.S. National Cancer Institute are
now studying companion animals.
Learn what cancer is, how it is diagnosed and treated,
and includes the ten common signs of cancer in small
See the brochures listed below.
Medical Association Brochures about Cancer in Animals
Cancer in Animals
Cancer in Animals