Have you tried feeding him any of the canned foods (Nature’s Variety Instinct, Merrick, etc.), fresh commercial foods (FreshPet, Just Food For Dogs, etc.), or considered cooking for him (Just Food for Dogs is a good option if you need a recipe)? Digestive enzymes may help as well as some alternative therapies such as herbs, acupuncture, food therapy, etc.
Westies are sort of known for exactly these sort of issues you’re describing. As they get older, it can definitely be even more of a challenge to figure out.
I’m a holistic veterinarian in Phoenix. If you were in my town, I would evaluate all of his symptoms, habits and preferences to try to identify imbalances. Then I’d use acupuncture, Chinese herbs and food therapy to help balance him. If you’re interested in this sort of veterinary care, you could check if there is a vet near you who knows about TCVM here: http://tcvm.com/Resources/FindaTCVMPractitioner.aspx
If you would like to read my articles about pet food, here is a link: http://naturalalternativesvet.com/category/blog/food-therapy-for-pets/
Good luck!
Tabitha
