We deliver our meals to hundreds of dogs with sensitive digestions, and they're doing really well - in particular, we've seen solid improvements in dogs with loose poops.
Have a look at our reviews on Trustpilot here - you might read about how we've helped a dog with similar issues to yours. Our chicken and turkey recipes contain less than 5% fat and are extra gentle, so we are confident they'll will get on really well with these.
We'd suggest that you take it extra slowly with transitioning your dog over to Butternut to avoid any stomach upsets, particularly if they've been eating a commercial diet or dry food. After a few days, they'll be moved over to Butternut fully and you should start seeing the benefits of their new diet.