Donor Horse Serum is a sterile, light brown-colored liquid collected from controlled standing herds of animals located entirely in the United States. Animals are inspected periodically by a licensed veterinarian. Diet and worming are strictly controlled and documented to ensure all animals are healthy. Each lot of Donor Horse Serum is extensively tested, and must be negative for Equine Infectious Anemia (EIA) and Equine Viral Arteritis (EVA). Chemical constituents are measured further to ensure lot-to-lot consistency.