Heaves or Chronic Obstructive Pulmonary Disease (COPD)

Image: Kottenbelt, Derek C. and Reg R. Pascoe, ed. 1994 Color atlas of diseases and disorders of the horse Amsterdam: Elsevier, page 108.
The arrow points to a heave line.

What is heaves or chronic obstructive pulmonary diseast (COPD)? For an excellent article Cooperative Extension Service/University of Kentucky/Heaves in Horses

For a complete visual explanation to see what is happening in heaves follow this link. It is excellent! Infographic: Heaves