See your veterinarian is you see any of the following symptoms:

Abnormal swellings that continue to grow.
Check lymph glands, nipples, mouth, abdomen and testicles.

Sores or ulcers that do not heal in two weeks.
Check the ear tips and nose of white cats exposed to the sun.

Weight loss, loss of appetite, energy loss or pale membranes.

Bad breath, loose teeth, offensive odor, chronic sneezing, or runny eyes or any discharge.

Difficulty eating or swallowing, salivation, and/or vomiting.

Difficulty breathing, urinating or defecating.
Check for diarrhea or constipation.

Trouble walking, hesitation to exercise or lethargy.

Persistent lameness or stiffness.
Check if legs bear weight or if they are held up off the ground.

Bleeding or discharge from any body opening.

Increased water intake or urine output.
Check kidneys, liver, glucose calcium, hormones, etc.