Tetanus is caused by a bacterium (Clostridium tetani) that is present in soil everywhere. Horses become seriously ill and in many cases the disease is fatal despite all attempts at treatment. The bacteria enter the body through cuts in the skin, and then cause disease by producing toxins that affect the nervous system, ultimately paralysing the victim. Fully vaccinated horses are able to neutralize the toxin before it can cause any ill effects and disease is completely prevented.

All horses should be vaccinated against tetanus whether they are retired, companion or competition animals.