At our regular check up our vet felt a mass in his belly. He did an ultrasound and confirmed a mass but said we would need to go to a specialty facility for an ultrasound-guided aspiration. We did so and the results came back inconclusive. Our cat is almost 18 and is not sick at all--can still jump on the counter when he's hungry, eats like a horse and doesn't vomit or anything. He does have some kidney levels that are a bit off. The oncologist said she would do nothing since to find out what he has would require surgery to take a piece of the tumor and she was concerned about putting him under anesthesia. He is now on a kidney diet (thank goodness he likes it) and continues, two months later, to be fine. The thought was it could be a pancreatic tumor but everything I've read said he would be sick. We are going for a re-check next month. Has anyone ever had a cat with an abdominal mass that was nothing? He has actually gained a few ounces since his non-diagnosis since we feed him now whenever he meows for food!