Our 2 boxers do fine cabled to the same back jack but I don't know how a 3rd one would do. I'd probably shorten their cables and put #3 on a front jack. I try to keep ours tired out so they're not moving around much at our site and each has a comfy cots with a pad on it so they're usually tired and comfy and sleeping. I don't know if tying to the jack on your TT would be advisable.
I use Frontline Plus and it controls ticks just fine. The ticks will attach and it takes a little time for them to die but they do. I still check the boxer kids at least once a day and pull off any that are still kicking as well as dead ones. I haven't tried Comfortis but have heard about some problems.
