Conventional wisdom states that the Animals version, apart from popularising the 'boy' variation, electrified Dylan's /Van Ronks acoustic arrangement. But some time ago I got a CDROM called Highway 61 Interactive in which you could wander around Greenwich Village, CBS recording studio etc. In the studio were several tapes of Dylan you could click on and listen to, the first takes of Like A Rolling Stone in waltz time, for instance! One of these tapes is an electric version of HOTRS, recorded in 1962. The Animals made their version in 1964. So maybe they heard Dylan's electric version, too!