Can we break our lease?

I have just recently move into a town house in Ohio and I have signed a 6 month lease. This apartment complex allows dogs and so each tenant has to sign a pet rules form. In the pet rules form it states that each tenant must have control over there dog and must be on a leash at all times while outside. We were also made aware that the weight limit for a dog is 65 pounds.
Several days after moving in I was taking my dog outside (on and leash and under my control). The tenants living directly across from my apartment had there dog out as well (on a leash). As soon as the dog saw me and my dog it began running towards us with the owner unable to control the dog (their dog is Mastiff so at least 100 pounds and well over the weight limit). I was barely able to get back inside my apartement and several minutes later the other tenant still could not maintain control of her dog. This happened again several days later where the tenant could not control her dog outside. The dogs intentions are still unclear but the lack of control is very concerning.
I recently filed a complaint with the landlord but her response was that the other tenants have lived there longer and they have had no problems with the dog before. She also stated that the building I live in and the building the tenants live in have an "understanding" about the dog and that they simply try to not let the dog out while other dogs are out. This was NOT broughten to our attention or else we would have not signed the lease. Her advice was to either not use my back door (where the yard is) or to flash my lights outside to let the other tenant know I am coming out with my dog. I no longer feel safe outside of my apartment and I am hoping we can break our lease or at least make the other tenants control their dog or move. What can myself and my roomate do to remedy this situation. Can we break our lease early? Will we most likely have to pay penalties? Any advice would be greatly appreciated! Thanks!

You can't break your lease because of this. You can let the LL know, in no uncertain terms, that this dog and its behavior is a violation of their own pet rules. Insist that they make the other pet owner control this animal. Let them know that you have the right to use the door and the yard for your dog just as their rules state. Also let them know that if anything happens to you or your pet beacuse they refuse to make the owner control the pet, that they will be responsible. Keep copies of everything in case you have to later prove you have notified them of this problem.

File a complaint with the LL each time you have a problem with the dog. If it appears the dog is out of control, also call the police or animal control. If you are forced to use another door, flash your lights, or any other absurd thing, ask to be reimbursed for the inconvenience. Could the yard be divided with a 6' fence so you can have your own area to walk your dog safely? If so, ask for one. If you complain enough, they LL may allow you to get out of your lease. If he does, get it in writing that you are being released from all obligations under the lease. Expect your lease to be non-renewed at its expiration. Give proper notice prior to the expiration of your lease that you will be moving, then move out.