The thumb sucking is a good comparison. With my dog it usually starts out like this, she's chewing on a nylabone or rawhide, then she stops chewing and begins to lick the rawhide, then she slowly progresses to licking her paws, the other times she does it is when she's lying around doing nothing. It not that big of a deal, just annoying to me and I worry it might cause some skin irritation.

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