broken wind

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A pulmonary disease of horses; the heaves.

from the GNU version of the Collaborative International Dictionary of English.

• (Far.) The heaves.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A respiratory disease or chronic condition of horses involving an allergic bronchitis characterised by wheezing, coughing and laboured breathing.
• verb Past participle of break wind

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a chronic emphysema of the horse that causes difficult expiration and heaving of the flanks