Thank you for recommending Burns Venison and Brown Rice for my westie.  She loves it (absolutely hated the Royal Canin and only ate it when she was really hungry) although still mixing the two together at the minute.  Don't know why though as she very carefully eats one and leaves the other.  She does seem to be improving but some days are better than others.  But at least I've found a food she actually likes and I'm hopeful that the bacterial overgrowth is settling down.