Topics of articles in this issue include: Unraveling the Cause of Cardiac Arrhythmias (Robert F. Gilmour, Jr., Thomas J. Divers); Study Points to Prognosis for Lame Racehorses (Susan L. Fubini); How Does High-Intensity Exercise Affect the Immune System? (Dorothy Ainsworth); Cornell Offers Horse Lovers the Latest on Equine Health.