I also had problems with Eukanuba!!! i switched to Royal Canine and his stools hardened right up ...
but you need to do a gradual change ... i did like a 4:1 mix for about a week... best of luck to you .. I know how frustrating it can be ..also with Eukanuba my 3mnth old puppy was noticablely loosing hair which also seems to be not happening since i switched ...