There is a pet policy in my lease saying "no pets on the premises" A friend brought their dog over for a few hours and someone told the landlord. Can they fine me if the landlord didn't even see the dog?
Having a guest with a pet visit for a few hours is not at all the same as keeping your pet in the residence as a tenant. It is not something you would get into trouble over... though there are surely some cranky people out there that couldn't just let it go. Whether the landlord saw the dog or not doesn't matter- you don't own a dog and don't keep one at the residence so you are not violating your lease.