2 month rental with possible dog problem

[Preda Spreda]

Hello everybody,

I have a duplex, where one side of it is inhabited by a person with a dog (we have a contract with him until the next year). He has a pitbull, and it's very well behaved and nice overall. But it is not on the leash the whole time, sometimes he does escape to greet and smell people. 

And I am worried when the tenants for the other unit come in, he may attack them or something. Now this is very unlikely, because the dog is friendly as I said before. I am trying to prepare for the worst here and thinking about what ifs.

Does any of you have experience with similar case? Or which insurance to get? Is there like a pet liability insurance or something that I can buy for the period until the lease is up. Let's assume we can't nullify the lease or evict the person with the dog.