You don't take your birds to the vet? Ever...?
Different strokes for different folks - plenty of folks maintain flocks and don't use veterinary services for them, some because finding a vet who will treat chickens can be difficult (if not impossible) in many places - and others because they don't view the chicken as a pet, but more as "livestock" and they can't/don't justify that sort of expenditure on a livestock animal.....and still others because they prefer to do their own "doctoring" based on their experience and knowledge (which often is more than that of the vets in their area when it comes to chickens)