We had a pretty good idea who was doing the damage, because that tree had for years provided shade for the canine inhabitants with nary a nip on its leaves. Then we got Maggie.
We knew Maggie couldn’t keep her secret forever. Eventually she showed off her tree-trimming abilities: jump, grab branch, twist, gnaw it off.
Border collies need to work. If they aren’t provided work, they will find something to do.
Anyone need some tree-pruning done? I know a dog who works cheap.