If you have a dog who understands what water
is and the the boat is floating in it, unless your pet is especially clumsy or dumb, lifeline netting while at the dock
is not really very helpful. After all you (probably!) don't worry about your dog falling down stairs, or jumping off bridges.
Underway it is quiet another matter. I installed our netting a bit at a time, as the opportunity presented. Our dog was out sailing several times with the boat partially netted, and he was obviously more comfortable around the netting then the bare lifelines
Whenever we are out sailing he wears a harness with a lifting strap so if he was to go overboard
we'd have a place to lift
him back onboard with the boathook.