I have a "no pit bull" rule for my rental and put it in the lease. My first set of tenants got one after they moved in, I found out and told them to get rid of the dog or they have 30 days to vacate and I get to keep their security deposit.
I have animosity towards the breed. Almost lost 3 fingers to one as a kid. Same dog that bit me, mauled a 6 month baby, daughter of the dogs owners, 3 weeks later.