Yes, it makes a difference what state you live in, what type of containment method you use to keep the dogs under control, and where the attack took place at.
Since there are no witnesses, other than the animals, and you've admitted that the dogs were at large, I would say you are definitely liable for the veterinarian fees.
We keep our animals contained within the fence, so any animal jumping the fence and attacking our animals is not our responsibility. The animals are not left outside unattended, either, there are visuals available through the windows, and sliding glass door.
We do this since we have the nasty neighbors next door and the ones on the other side of the nasty neighbors let their dogs loose through their back yard. The next door neighbor complained it was our dog doing the damage, and only recently since they finally fenced in their back yard did they actually see the dogs running across the back of their property behind the fence.
We have physically removed all the animals who come inside the fence without injury. It's getting old to keep doing this.
How, exactly did your dogs escape, and how often do they escape contained area?
