Currently feeding our 4.5 year old lab arden grange light. She's been on arden grange a her life and previously done really well on it. Over the past year we have had to add a fibre supplement as she's been needing her anal glands done quite a bit and still drags her bum. The vet has suggested looking at trying a different food - any suggestions? She's not massively overweight but is currently bigger than I would like. I'm not in a position to try raw so will need to be another kibble type food.