Cory (our older cat) gets “bit” about once every week or so, but has not crossed the line in the last 8 months. The amazing thing is Ping (our younger Siamese) stays in the yard as well. We think that Cory has taught him that he is not supposed to leave the back yard. Karel caught him in the front yard one time last spring, fussed at him and scared him a great deal, and he has not left the fenced back yard area again. A couple of days ago, a squirrel came to play in the trees, harassed the cats severely, and even dropped down and ran along the top of the wood fence before he jumped down into the neighbor’s yard. Ping ran over and looked through the fence and sat there for 15 minutes waiting for it to come back, but never even acted like he was going to go over the fence. I am convinced that they communicate with each other much more than we think and that Cory has convinced Ping that bad things will happen if he crosses the magic line. Ping goes right up against the fence to catch mice etc., and Cory knows he can’t get that close. It’s funny, but so far everything is working fine.
Ping finally started violating the area and it took a DG-9000 to keep him controlled. He is smart enough to get his collar tilted away from the trimmed area (he is smart enough to change the setting on the cat door to let himself out) and we had to use the maximum on him the few times he messed up, but it keeps him in now. We have added a third collar for our third cat (The White Tiger) who was a year old Tom when we found and neutered him. He never leaves the yard.
Thanks again for all your help.