I would recommend Juven to help with intestine and surgical wound healing, that is if kidney function and liver function are within normal limits. Vital Jr. is a sole source supplement, like Ensure, only semi-elemental, that is very palatable. I would also encourage high pectin foods like bananas and applesauce to help gel his stool. It is also quite possible that a probiotic supplement, like Florastor, may be helpful, as he sounds as if he may be a risk for an opportunistic bowel infection. I would strongly encourage you to seek out help from your local Registered Dietitian, as these are only general suggestions based on limited information.