[bobohyde]

I used to have invisible fence with my golden retriever. He was 100 lbs. I've accidentally zapped myself on his collar several times and let me tell you it REALLY shocked me. I would never use invisible fence on Columbo both because of his size and his personality. I think it could possibly hurt him physically, but definitely would hurt him emotionally. He'd be cowering and shaking and really traumatized. Yorkies are tough little guys, but they are also fragile emotionally. Also, the collars have to be tight to keep the prongs in contact with the neck. Even the smallest prongs would hurt or even puncture a yorkie's neck. They definitely wouldn't be comfortable for him. The transmitter on the collar would also be large for a yorkie. Even the smallest ones. I definitely recommend against using invisible fence on a yorkie. If I am working in the yard and want Columbo with me, but can't constantly be chasing him, I set up his x-pen so I know where he is. I agree with the other posters about finding a better fitting harness. There are lots of good ones out there and different styles. I think you find one that can't be slipped out of so easily.