Hi there. I am sorry to hear that your dog is suffering from the same disease as mine. Have you been to the vet yet re the black stool? Peroxicam can be tough on the intestines/stomach and kidneys. Mine is struggling with appetite too. She is not on peroxicam anymore as it caused elevations in her kidney numbers. This did not cause the appetite problem. She also has good and bad days. I really wish you well with everything. Did the vet give you six months from September or April? How advanced is the cancer and where is it located in the bladder?