Hi Diane, I did find your post informative, thanks for writing as I am pretty new to operant conditioning. My dog has no aggression issues whatsoever, but it might be handy to know about in the future or to help someone else whose dog might have guarding issues. So I for one am glad you wrote that. I have kept many of the posts you have written because they are so well written and well thought out. Thanks. AnnaLisa and Sundance No virus found in this outgoing message. Checked by AVG. Version: 7.5.524 / Virus Database: 269.24.2/1471 - Release Date: 5/28/08 5:33 PM