Hi Narayanan,
Look for a dry kibble that has limited ingredients & is lower in Kcals per cup under 360kcals per cup, the lower the Kcals the kibble is easier to digest, also fat keep the fat under 14% max..
Mast Cell Tumors attacks their stomach causing acid refux, vomiting, bloody stools, their stools will be black sometimes. If you can cook some of his meals it will be heaps better for his stomach…
Look at “Wellness Core” large breed formula, https://www.wellnesspetfood.com/natural-dog-food/product-catalog/core-large-breed-large-breed
My boy isnt a large breed, he’s a 9yr old, medium breed with IBD, he went down hill last December 2017, became sicker & sicker, then in March 2018 I started him on the Wellness Core Large breed dry kibble cause I could return if it didn’t agree with him, the Kcals were low-346 per cup, the fat is 13% max, the protein -34% & the carbs – 30%, after eating the Wellness Core for 2-4 weeks he became well again & is his old happy self again…
