For optimal relief, homes with indoor pets should have professional air duct cleanings done every 12-24 months. This frequency ensures accumulated pet dander, hair and other debris do not have time to extensively build back up inside ductwork following cleaning. Annual maintenance visits also allow homeowners to monitor system conditions. Checking ducts through accessible ceiling vents between cleanings lets occupants see when airborne dust or pet hair visibly re-accumulates. Any visible debris buildup signals it's time for repeat professional cleaning right away.