my pets at home fitted our harness for us with no problems. It's made ahuge difference for us, no more chokig pup and he's actually walking beautifully with it on.
However, my mum was holding on to Jasper the other day while I popped in to a shop and a passing man told her that "that kind of dog shouldn't be wearing a harness, they're only for bull terriers...you'll damage his stomach" So it's better to damage there necks then obviously
Perhaps he works at you pets at home? lol!