Dogs get cancer at roughly the same rate as humans, according to the American Veterinary Medical Association. So how can you spot potential signs of cancer in your pets? Pay attention to changes in the way your pet eats and moves, advises Dr. Nick Szigetvari, who is certified in veterinary oncology. In cats, look for minor changes in appetite and grooming, since they may hide their symptoms. In dogs, check for any lumps, swelling, limping or wounds that take longer than a week to heal.