My 11-year-old cat, Mr Big, had his back leg amputated in December, after being diagnosed with basal cell carcinoma. The vet did ultrasound and x-ray before we decided to amputate, to make sure that the cancer was only in his leg. The surgery was successful and after very stressful first two weeks (which included Mr Big somehow ripping his stitches off and a visit to vet emergency room on Christmas Day), our kitty seemed to be doing very well. He was very sociable, got his appetite back, was even interested in playing with his toys and going outside (supervised). He does have some problems occasionally with getting up, almost like he was trying to use his amputated leg. From what I've read on this forum it's not uncommon and should disappear with time. I am concerned, however, because just recently he seems to be eating less than before the surgery. He now leaves the food in his bowl, he never used to do it before (his name, Mr Big, is because he is indeed a big cat). He spent one day in hiding and now I noticed a lump underneath his wound. He does not like me touching it, seems it hurts him. Of course my first scary thought was that the cancer is back, but then I tried to remember that his original basal cell carcinoma did not appear as lumps, but as never-healing sores on his leg. Could the lump be simply caused by scar tissue? Of course I'm going to call the vet, but wanted to hear what you think as well.