The problem with the chicken bones would probably be that he needs to get used to them - with any change of food it is likely that poos will be softer etc so you could give them another go. However, I don't feed raw so I don't know how they would help re: anal glands.
It is my understanding that a dog needs a diet high in fibre and animal protein in order to express the anal glands effectively. Therefore a food like orijen which is animal protein and veg would be ideal - as it gives firm poos.
Naturesdiet is probably a good idea as again it is high in animal proteins from meat but also has veg in. I think although can't tell from the website that Wainwrights doesn't have any veg in. (Just meat, rice and some added bits) So if you want to stick to feeding wainwrights and you have the time could you just add in some cooked veg at each meal mixing it in with the wainwrights? Carrots, peas that sort of thing. Dog find it hard to digest vegetable matter so I think it does need to be cooked or pulsed.

Even if Wainwrights does have Veg in (and P@H just dont want to tell me on their website

) you could just add more veg as a source of fibre.
I also don't think I would give him weetabix as I think they can lead to softer poos which wouldn't express the glands effectively - however, maybe keep doing it for a least a week or two longer as it may have an affect - every dog being different and all!

I think veg is more dog friendly - so that could be something you try next if this doesn't work.
Its so hard to know what to do when they have a problem which isn't easily sorted. I hope you find something that suits Marley soon.
