Source : Webster's Revised Unabridged Dictionary (1913)

Heaves \Heaves\, n.
   A disease of horses, characterized by difficult breathing,
   with heaving of the flank, wheezing, flatulency, and a
   peculiar cough; broken wind.

Source : WordNet®

heaves
     n : a chronic emphysema of the horse that causes difficult
         expiration and heaving of the flanks [syn: {broken wind}]