What is Tetanus?

Tetanus, is an often-fatal bacterial disease caused by the organism Clostridium tetani, which is found in soil and droppings.1,2 It’s found all over the world and can affect humans as well as horses.

The bacterium can survive as spores in the environment for long periods of time, and while it is in the soil, it’s harmless. However, the bacteria can enter the body through wounds, particularly puncture wounds, if the wound is dirty. The tetanus bacteria do not need oxygen (they are classified as ‘anaerobic’ bacteria) and so they multiply rapidly in the damaged tissues at the site of the injury.

The bacteria produce a powerful nerve toxin, causing distressing symptoms and death in about 80% of cases.1

There may be a delay of 1 to 3 weeks after infection, before symptoms of tetanus appear.1 More commonly, symptoms will appear after 9 or 10 days.1

Tetanus attacks the horse’s central nervous system. The bacteria produce a powerful nerve toxin, which causes many muscles of the body to spasm uncontrollably, so the first sign of a problem may be a change in the way your horse moves and stands at rest.1

Affected horses will have progressive muscle stiffness, causing:

  • The tail to become stiff and stand straight out1,2
  • The ears to stand erect1
  • An anxious facial expression caused by facial muscle stiffness – your horse may look like it is “smiling” strangely2
  • Eating difficulties.1,2

Tetanus also results in another telltale sign – the third eyelid goes into spasm and protrudes across the eye, especially when the horse is startled1,2

Over time, more and more muscles go into spasm. The horse will have convulsions and respiratory failure.2 Within a few days of the first signs appearing, about 80% of horses will die.1

If you suspect your horse has tetanus, contact your vet immediately as early treatment offers the only hope of survival.1,2

The risk of tetanus is pretty much everywhere as the organism that causes it, Clostridium tetani, lives in soil and manure and it enters the body through wounds.1,2

Horses are particularly at risk because of their environment and tendency to injure themselves.2

The good news, however, is that tetanus is not contagious, so it is not passed from horse to horse.

Sources of contamination

  • Horses can become infected through gastric or intestinal ulcers after eating contaminated soil or droppings.
  • Wounds, especially deep wounds, are a key source of infection. Common sites of infection are the soles of the horse’s feet, although even a simple thorn prick can allow the bacteria to enter the body2 Surgical wounds are another possible source of entry for the bacteria.
  • Foals can become infected via their navel where the umbilical cord was attached2
  • The mare’s reproductive tract may also become infected, if it’s damaged or the placenta is retained.

Minimising risk

Tetanus can be avoided with vaccination.2

Ensure your mares are well-vaccinated before having a foal: foals may not respond to vaccines early in life so it is important they receive protection via their mother’s milk.

Remember that humans can get tetanus too, so ensure your own tetanus vaccination is up-to-date.

Tetanus is a totally and easily preventable disease. Vaccination with ‘tetanus toxoid’ should be used for all horses and ponies2.

You can vaccinate your horse against tetanus with Equivac® T or Equivac® 2 in 1, available from your vet.

Your horse can get this vaccination from 3 months of age. If using Equivac T, the primary course is two doses no less than 4 weeks apart. The Equine Infectious Disease Advisory Board recommends a booster dose every 12 months to ensure maximum protection against Tetanus.

For immediate short-term prevention of tetanus, your vet may suggest Equivac® TAT.

Your horse can get both immediate prevention and long-lasting protection with simultaneous injections of both of Equivac® TAT and Equivac® T.

If suitable, your vet may suggest Equivac® 2 in 1, a combination injection that protects against strangles as well as tetanus. The recommended protocol for this product is in the section on strangles.

For more details about the Equivac® range and correct dosing information, visit the Products section of this site.

Myth: Tetanus is straightforward to treat.

This is untrue: about 80% of infected horses die from tetanus.1 If diagnosed early, your vet may treat your horse with large doses of antibiotics, usually penicillin, and administer the tetanus antitoxin injection.2 Sadly, however, many owners are still faced with having to euthanase their horse on humane grounds.2

Myth: Tetanus is caused by rusty nails or rusty fences

When your horse steps on a rusty nail or is scratched by a rusty barbed wire fence, it IS at risk of tetanus, but that’s not because of the rust; it’s because of the tetanus spores on the nail or the fence.


  1. Hoare R. Horse health – vaccination against tetanus and strangles. PrimeFact 495, June 2007. NSW Department of Primary Industries. www.industry.nsw.gov.au
  2. Queensland Horse Council Inc. Tetanus Fact Sheet, May 2010.

Don't Wait to Vaccinate



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