Tenant's Dog running loosely around the back yard-Multi Unit

[Mario Morales]

I have two nice tenants who let their dog run around in the backyard. Its a golden retriever. My spidy-senses tell me that the new tenant moving in will complain that when she wants to come in throught the backyard (thats where the parking lot is), that she has to wait for the dog to be held by the owners. The dog is kind but big and jumps on people. Should I address it now and tell the dog owners that this might be an issue or should I wait until it is? It happened before in another building, where the tenant let the cat run around and it scared the other tenants.