"If any firm mass or red areas are present, then the pet should be evaluated by a veterinarian," said David Hunley, a veterinary oncologist with the Ocean State Veterinary Specialists in Greenwich, R.I. "The average age that these tumors are found is about 10 years in both the dog and cat."
According to the American Veterinary Medical Association, the most common signs of cancer in small animals include abnormal swellings that persist or continue to grow, sores that do not heal, weight loss, loss of appetite and bleeding or discharge from any body opening.
Pets with cancer may also give off an offensive odor, have difficulty eating or swallowing, show a hesitation to exercise or a loss of stamina, display persistent lameness or stiffness and have difficulty breathing, urinating or defecating. An owner should take an animal to a clinic if they notice any of these signs.
"Early detection and diagnosis is the key to great health," Ogilvie said, adding that if the cancer is detected early, animals have a good rate of survival. Then, they can continue to help amuse, annoy and comfort their human companions for many more years to come.