Legal Question in Real Estate Law in Massachusetts

You can amend the lease, but what is the reason for doing so. If the reason is to protect you from liability for the Pit Bull, that is not going to help.

Owner of a dog who bites has strict liability. Your liability will be based on knowledge of the Pit Bull being in the premises and then allowing an unsafe animal on the premises. If you want protection for the actions of the Pit Bull, you will need to do more to protect your interests.

She is responsible for the action of her dog, your liability will stem from other issues.

If you want assistance, you should contact an attorney as to the various ways to limit your potential liability.