New tenant's boyfriend's dog

[Mike Adams]

We just turned over a unit and placed a new tenant in the unit.  She's a young 22 year old female, and stated she has no pets.  However, her boyfriend sleeps over on the weekend and has a medium sized dog.  She knows we have cameras and we are turning over a unit and see the dog nearly daily.  Any suggestions on how to deal with this? Since the dog is her guest's dog, would this be a lease violation? If so, how to rectify this?