Gastrointestinal parasites cause significant economic losses and are listed in the top three fatal conditions in sheep and goats. Internal parasites in sheep and goats cause disease when they are present in large numbers or when the host animal is weakened by another disease or by poor nutrition. Damage to the host occurs when parasites attach to the lining of the gastrointestinal tract and ingest blood – large numbers of parasites can create anemia from blood loss.