I'm gonna be honest I dunno what to tell you here. "Killed" a dog, it came back some time later several feet above the ground and eternally attacking me. Neat trick.
#Freed Ode Dog Returns
vapid rampart
minor cliff
Happened to me a few times but only today did it come back levitating
Generally it would return aggressive as ever and keeps haunting me since it has no HP it's immortal
valid sapphire
Had that happen to me once and the dog took out a bunch of ode first, so I thought maybe it was a new feature in the game that dogs you 'save' from ode influence try to help you? (I wasn't using Orengall pact, so I know it wasn't that.)
Then it turned on me after the ode were gone, and yeah, it's immortal, so... had to relog to get it to go away.
Never saw it levitate. That's new. 
red knoll
Same happened to me. Had to escape it by going into the Glades
main lintel
I confirm, the immortal dog has returned.)