Your landord owns the unit that you had occupied for six (6) years that you no longer have. You had a dog occupying the unit while you were there which apparently caused damage to the unit. Your landlord has a right to ask questions about how the damages occurred and if more than one canine had been in the rented unit during your occupancy.Your landlord's questioning on the subject does not seem out of the ordinary. Potentially his questions about the number of dogs being in your unit will assist him with requirements of security deposits for other tenants in the future who have animals that he may rent to.