By Susan Milius
Air sacs bulging from a horse’s hearing system may solve the mystery of how such an athletic animal cools its brain during exercise without the standard anatomical gadgetry, argues an international team of researchers.
In gazelles, cheetahs, dogs, and a herd of other zoological athletes, brain cooling depends on a structure called the carotid rete mirabile, explains Keith E. Baptiste of the Danish Veterinary Laboratory in Copenhagen. In the rete, hot blood surging from the heart via the carotid artery flows into smaller arteries surrounded by cool blood returning from the nose and face.