We too just bought the illusion collar for our 4 year old boxer, and I have to say I am amazed with how beautifully he is walking. We had tried just about every collar on the market and he still dragged us along the street barking at every person, car etc. The illusion collar along with Ceaser Milan's tips have transformed our unruley baby in the space of one week!!!! Its now a pleasure to walk him. If I did have any concerns it would be does the collar hurt him?? I know I am such a worrier when it comes to our dog and people are constantly reminding me that if the spiked choke collar didn't hurt him then nothing would. It doesn't seem to bother him and he acts comfortablly with it on.