I'm sure your Jack Russell will be fine . My son has a Jack Russell/Patterdale cross and he is very relaxed in the threewheeler , he was a bit restless the first time , but soon settled down , on long journeys he usually he goes to sleep on the floor . Having said that he is a sensible sort of dog ! and never goes on a lead .
Not got round to getting him a helmet and goggles yet !
