Clostridium tetani is a rod-shaped, anaerobic species of pathogenic bacteria, of the genus Clostridium. C. tetani is found as spores in soil or in the gastrointestinal tract of animals. C. tetani produces a potent biological toxin, tetanospasmin, and is the causative agent of tetanus, a disease characterized by painful muscular spasms that can lead to respiratory failure and, death. The bacterium enters animals either through deep traumatic wounds, during parturition, or as a consequence of management procedures. Horses are more susceptible to tetanus than other animals and soil contaminated with horse manure commonly contains tetanus spores.