From: Equus Caballus Spring 2007 (Article by Tracey Williams)
RE: Ammonia/Health Effects

“According to the International Veterinary Information Service, researchers M.S. Davis and W.M. Foster released a paper indicating that as little as 10 ppm for 5 to 7 weeks can cause dysfunction of the horse’s mucus membranes, which decreases immune response and makes the horse susceptible to other pathogens.”

In 2001, Michigan State University’s Equine Pulmonary Laboratory released a study, which found that stabled young horses during training suffer respiratory distress compared to young horses that are pastured during training. The researchers reported – “We conclude that stabling is associated with inflammation of both the upper and lower airway of young horses.”

The article also reported – “Ammonia’s effects are exacerbated in foals, according to Frederick Harper, PhD and extension horse specialist for the University of Tennessee. According to Harper, approximately 15 percent of all foals suffer a severe respiratory disease before they are one year old, although most occur between 2 to 6 months. Since foals spend a great deal of time on or near the stall floor, ammonia exposure is heightened.

From: The Horse: Your Guide to Equine Health Magazine Feb. 2004 (Article by Michelle Anderson)
RE: Ammonia/Health Effects

Ms. Anderson’s article makes the point – “Those warm, closed barns compound the ammonia problem as the heat spurs on bacterial growth while also agitating ammonia molecules and causing the gas to rise.”

In the article, Karen Hayes, DVM, notes that ammonia is a caustic gas. “Besides just being unpleasant in a barn, ammonia gas burns the delicate tissues of the respiratory tract and the eyes and increases mucus production.”