Pericarditis, a scary-sounding word, is a killer in the current situation of equine illness that first manifested itself in foal loss, and now is causing problems in horses of all ages and sexes.

Pericarditis is fluid in the pericardial membrane surrounding the heart. Dr. Doug Byars, director of the internal medicine unit at Hagyard-Davidson-McGee in Lexington, Ky., explained that the sac can only stretch so much, and when there is too much fluid, it compresses and compromises the heart. He said that there have been 20 cases of pericarditis at Hagyard's and Rood and Riddle Equine Hospital in Lexington in the last week.

Byars said in these situations, he has taken six to eight liters of fluid from around the hearts of adult horses, and a couple of liters of fluid from around the hearts of babies.