When a pigeon flys it brings down a third eyelid to protect its eyes from the wind! But if it has problems with its eyes (ie respiratory problems) it can't bring this 3rd eyelid down. It flys homefrom the race with its eyes half open. How many time have you had a bird return home from a race with swallen eyes as if they had ben pecked in the basket? Try driving your car at 40MPH and stick your head out of the window, you will not be able to see for the tears running down your eyes!!!!Respiratory problems aren't just in the nose, throat or Crop!