Good for you, taking him in to be checked. His health will benefit from that veterinary visit, and so will your peace of mind. God bless you!
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Kathy Diamond Davis, author, "Therapy Dogs: Training Your Dog to Reach Others," 2nd edition, and the free Canine Behavior Series articles at http://www.veterinarypartner.com/Content.plx?P=SRC&S=1&SourceID=47