Westies are prone to skin conditions , sometimes caused by diet ! what do you feed him , has he always been on this food or is it a rescent change , have you used Fabreze in the house as this is terrible for dogs and can cause skin problems , if you can rule out any external factors then the next thing is maybe its an anxiety condition , some dogs will lick and lick at thier paws from anxiety bought on by a change they dont like , arguing betwwen humans a new addition to the family a new dog next door etc , it manifests its self in them almost self harming .
I had a dog years ago that did this during the time my ex husband and i were going through our wosrt time with arguing before we eventually split up , i didnt know at the time that this was the result of our actions . Hope some of these ideas help .

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