Hi everyone, I’m a newer landlord and trying to understand expectations around inherited tenants.

I inherited a tenant who has a large dog. The dog is not listed anywhere in the written lease, so technically and legally the tenant is not authorized to have a dog in the unit—though the dog was already present when I took over ownership.

I’ve allowed the situation to continue so far because I don’t want to create conflict, but the issue is that the dog barks very loudly whenever someone uses the back entrance or stairs or walks on the unit directly above. The dog is alone most of the daytime and sits in a room directly next to that entrance, so this happens often. During showings, the dog always barks, which doesn’t create a welcoming environment for prospective tenants.

I want to be fair to this tenant, but I also don’t want future tenants—who will be paying closer to market rent—to be negatively affected by ongoing noise issues.

What’s the best way to approach this? Should I begin documenting the barking and notifying the tenant? How would experienced landlords handle a situation where the dog is technically not authorized under the lease, but has been informally tolerated?

mind you this tenants is waaay below market rent- but super nice overall. 
I also worry about this large dog being in the building, as in my screening I dont allow dogs over 40lbs. What would a new tenant say if they saw him?