Volkheimer leaps immediately into a squat, his head coming around as the hounds release toward him, and Werner’s heart feels as if it has been blown to pieces in his chest. Volkheimer’s arms come up as the dogs charge him, but they know him; they are leaping on him in play, barking and scampering, and Werner watches the huge boy throw off the dogs as if they were housecats.
From All the Light We Cannot See by Anthony Doerr
As far as I know the verb 'release' is a transitive verb, needing a direct object. In the above sentence it is used as an intransitive verb. What do you think?