There is a dog bite statute that makes the owner of the dog, not the owner of the property, liable for dog bites, so you are safe there. Your liability as a property owner is limited to cases of negligence, and based on the facts you present I don't see what you did that was negligent. That said, hopefully you have insurance coverage on the property, so you can advise the insurance company of the situation and work with them from here on.
Owner of property is liable if they can prove you knew the dog had dangerous propensities before this bite. Also, if you were negligent. For ex., if landlord knows tenant has dog, and also knows the gate to the yard has been broken for months and doesn't stay closed, and dog gets out and bites someone.
It seems that your only legal exposure in this dog bite would be as "owner of the property". The issue of liability of a property owner for a doberman living on the property biting a passerby can get complicated. However, based on the additional facts you have stated, it appears that you were not in fact a legal owner of the property at the time of the incident. If you weren't an owner of either the dog or the property where the dog was kept, you should not be liable on these facts.
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