You are probably referring to a condition known as "bird fancier's lung". Which is often miswritten as "bird keeper's lung".
Bird fancier's lung is a form of hypersensitivity pneumonitis, a medical condition in which the lungs become inflamed with granuloma formation.
It is caused by over-exposure to avian proteins found in the dust of bird droppings (and sometimes the feathers of certain species).
Further reading: