Conditions or ailments that are the cause of a problem that you see - your observation.

Your vet may diagnose


Synonyms: Lockjaw


Tetanus is caused by Clostridium tetani, a bacterium that resides in the soil. The organism lives in anaerobic environments (environments with no oxygen). It gains access to the horse's system by colonizing an infected wound, especially deep and infected puncture wounds. There it produces an extremely potent toxin which affects specific (inhibitory) nerve endings in the spinal cord, causing constant muscle contraction of the main muscle groups.

Affected horses generally (not always) have a history of a wound. Their limbs appear stiff, their third eyelids cover their eyes. Their ears are typically erect, tails raised and nostrils flared. They rapidly reach a point where they cannot rise, and they lie on their side, with their limbs rigid.

Tetanus is well known for causing what appear to be seizures, brought on by loud noises. Beyond this classic appearance of affected horses, there are no diagnostic tests to confirm a diagnosis.

Vets "back into a diagnosis" of tetanus by ruling out other causes and by knowing that the horse has not been vaccinated for it. Horses with the third eyelid covering the eyes are tetanus cases until proven otherwise.

Treatment involves supportive nursing care, antibiotics, local wound care, and tetanus antitoxin. In some cases, vaccination may also be performed in the face of disease, but this is case dependent and depends on vaccination status.

my role


I might observe

You might make these observations when a horse has this condition.

Very Common
Less Common
more observations

Questions To Ask Your Vet:
  • What vaccination program should my remaining horses be on?

Vaccination is the single step that is necessary for protection. It is simple and effective. Vaccination should be performed annually, although protection MAY last longer. Tetanus vaccine is recommended as one of the "core" vaccines by the American Association of Equine Practitioners (AAEP).

If a wound occurs, be sure to discuss with your vet, especially if your horse has not been vaccinated. Deep wounds and those on the lower limbs are more likely to become infected. When in doubt, talk to your vet about any puncture wound sustained by your horse.

further reading & resources

Author: Doug Thal DVM Dipl. ABVP