Thank you Maggie, it may be just a thing with dogs, but mine has only recently started this behavior and was just wondering was he maybe lacking something in his diet.
do not know the answer to your question but i have a german shepherd who quite often licks our leather couch,,have not worked out why but does it and is healthy so live with it.
It's not an answer as such, but a sharing of experience! Our 2-year-old Collie licks ANYTHING! As well as giving us lots of "kisses", he licks carpet, bedding, rugs, himself! He is very healthy, and seems happy in his diet. It might be a reassurance thing; Jack is a very nervous dog, I don't know about your Yorkie?Not much help, sorry, but at least you know you aren't alone now!