Tetanus in Horses

By KC: Yesterday I saw a horse with early signs of tetanus. The horse was not vaccinated and had started to show signs of  a stiff gait, hyper-excitability (i.e. exaggerated response to noise and movement),  a slightly elevated tail carriage and easily visible 3rd eyelids (see pics.). Luckily it was still able to eat but as it was early stage things can potentially change to real “lock jaw”.  The condition is caused by a bacterial toxin that overstimulates the nerve ends and hence cause muscle rigidity.   The toxin is produced by a bacterium called Clostridium tetani which normally lives in the soil as it does not like oxygen.  The usual cause of clinical tetanus is when this bacterium gets in a wound which favours bacterial growth and production of the toxin. Another and less documented source for the toxin is entrance to the body via the gastro-intestinal tract as the bacteria can be found as part of the bacterial flora in the gut,  likely from soil ingestion. Treatment focuses on stopping the bacteria to grow  and produce more toxin (antibiotics), inactivate new toxin (with a specific antiserum) were possible and supportive treatment (sedation, force feeding if needed).  Success is not guaranteed and thus prevention by vaccination is much better than relying on a cure.