My question involves landlord-tenant law in the State of: Maryland

I signed on for a lease from August 2010-2011. When the end of that lease was coming up, my landlord (with whom I live) added an addendum to the lease extending it to August 2012. However, I now find the rent too expensive and would like to leave. If I give 30 days notice, is this possible?

Some details:
I have read my lease over (I have the original, by the way, he doesn't even have a copy), and there is nothing in it that mentions early termination other than if I default on the lease.

There is a clause that states "THERE WILL BE NO ANIMALS". I agreed to this, yet my landlord decided it was okay to get a dog without even giving me a heads up. This dog is awful and I would never have agreed to live here if I had known they were getting one.

My landlord is an attorney, and I don't know if I should anticipate this being difficult. Any advice would be much appreciated.

Thanks.