All food that is produced for working dogs is VAT free. I used to get 15kg bags of Super Greyhound for ridiculously cheap; about £8-£9. Now he's officially a Senior I do pay quite a lot more but still try and get working dog food - I usually buy Burns, their VAT free Canine Alert is very good for seniors as well as working dogs and while it's not cheap it is comparatively, and lasts a long time - I do have to feed less and it's good for keeping down the old paunch