I imagine anything on the skin can irritate enough to limp, but this breed is a pretty strong breed...so they take the low grade discomfort...a true limp is concerning.
I cannot think of any other causes other than neurological. I will try to notify one of the other vets on this site and see if she can help in the discussion.
Dr.Vamvakias
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Dr. D.A. Vamvakias
Veterinarian