TETANUS - Is it serious and should you vaccinate against it?

"Learn from yesterday, live for today, hope for tomorrow" - Albert Einstein

Quicknotes: Tetanus is a disease causing spasms (tetany), which is usually fatal to horses and humans. The bacteria lives in soil and usually enters the body through wounds, particularly airless wounds such as puncture wounds. Unvaccinated horses with a wound are given Tetanus Anti-Toxin (TAT), which provides immediate protection but only lasts a short time (2 weeks). Tetanus Toxoid is given as a series of injections for long-term protection, and as a booster for vaccinated horses with a wound. Different vaccination recommendations exist depending on the degree of risk, the age of the horse, and the past vaccination history.

More Detail: Tetanus is a serious disease as it has a high mortality (death) rate i.e. once infected, most people and horses die despite modern treatments. The disease is extremely painful, with the body wracked by muscle spasms. Horses are one of the most susceptible species, while cats, dogs, and birds are quite resistant.

The disease is caused by a bacteria (Clostridium tetani) which lives in the soil and is most common in warm areas with a lot of organic matter in the soil. It is anaerobic (lives in conditions without oxygen) so is most likely to survive in deep puncture wounds, wounds contaminated by soil, wounds with foreign bodies embedded in them, and where there is necrotic (dead) tissue. Puncture wounds of the hoof and legs, particularly if untreated, are the most common way a horse gets infected, but the signs may not show for 10-14 days i.e. the wound may be healed before the signs of tetanus occur.

Why is it serious and what does it look like?
The bacteria produces a toxin that affects the endings of nerves, triggering muscle spasms whenever the horse is stimulated e.g. movement or a noise near the stable can cause the horse to spasm all over its body. The spasms can be so severe that they can break bones, stop the horse breathing and cause heart failure.

Another name for tetanus is ‘lockjaw’, because the jaw muscles spasm and the horse cannot open its mouth to eat. Due to muscle stiffness, the horse stands with its ears pricked and tail extended and its legs spread to imitate a ‘sawhorse’. The third eyelid also comes across to cover most of the eye. Check Google images for many images of horses showing the typical signs and variations. There are also images of humans, children, and other species showing the extreme spasms that can occur. (NB: some images may be disturbing).

Can it be treated?
Early veterinary treatment is essential. Sedatives, pain relief, and tetanus antitoxin (given into the vein or spinal spaces) increase the survival rate, but the antitoxin must be given in the early stages. Wounds need to be drained, cleaned, and treated with antibiotics, while intensive nursing care is needed to ensure comfort and nutrition.

So why are there two vaccine types?
We all know that vaccination can prevent disease, and that a course of injections is normally needed to give maximum protection. The same is true for tetanus; however, for tetanus there is an anti-toxin and a toxoid.

Tetanus anti-toxin (TAT) gives fast protection (starts within hours depending on route of injection) and the protection lasts for around 2 weeks.

Tetanus toxoid (T) takes 10-14 days before it works but provides longer term protection. It takes this long for the horse to build up sufficient levels of antibody (antibody is the defence mechanism produced by the body in response to attack the bacteria).

So, TAT works immediately and will protect for around 14 days, while Toxoid takes that long to work but protects for longer. Can you see how these can be used together?

For a vaccination programme, the horse will be given Tetanus toxoid injections:

  • An initial injection. This gets the body to start making antibody, but the levels with drop down again if no further injections are given.
  • A second injection 4-6 weeks later (must be within this period to work properly). Boosts the levels higher and for longer.
  • Booster injections at intervals of 1-5 years. Maintains the levels of antibody high enough to protect against the disease.

Note that often a combined flu’ and tetanus vaccine is used, so the tetanus vaccination will vary to meet the needs of the flu’ vaccination programme (which requires more injections).

There is debate as to how regularly the booster injections should be given and there is no hard and fast scientific evidence to prove which system is best. Horse vaccinations used to be given at 5 year intervals, but because some horses contracted tetanus between 1 and 5 years after injection, it is now often recommended that they be given annually. In areas where tetanus is high-risk (i.e. there are large amounts of Clostridium tetani in the soil), horses should have an annual booster, which is usually combined with the flu’ vaccine.

Variations also occur in human recommendations. Although 10 years is generally regarded as safe for most people, those with high-risk careers or lifestyles (including working with soil and horses) may need more frequent boosters. People with significant wounds should have a booster if they have not been vaccinated within the last 5 years, as not everyone has high levels of immunity left by the 10 year point.

Mares are generally vaccinated 4-6 weeks before giving birth, to boost their own antibody level and to provide initial protection to the foal.

  • A foal from a vaccinated mare will have some protection when it is born, and then begins its own vaccination programme from 6-12 weeks old. If in a high-risk area, then it may be given TAT at birth then every 2-3 weeks until it is able to start its vaccination programme (tetanus toxoid vaccines are ineffective in the very young).
  • A foal from an unvaccinated mare has no protection at all, so is given TAT at birth, followed by antitoxin regularly until it is old enough to be vaccinated with toxoid.

Note: your vet may recommend different variations on the above timings, depending on level of risk in your local area and current recommendations from the vaccine manufacturers. However, these timings generally apply at time of writing.

What happens when my horse has a wound?
When a horse has a wound, the vet may give the horse a ‘jab’ against tetanus regardless of whether or not the horse is vaccinated.

  • Vaccinated horse: the horse is injected with tetanus toxoid to boost the antibody levels. In general, being vaccinated will provide protection the horse but all horses are individuals and an additional booster will further reduce the risk of disease.
  • Unvaccinated horse: the horse is injected with tetanus anti-toxin to provide protection. It will also be started on a vaccination programme (using tetanus toxoid) to provide future protection. Therefore, it may get ‘two tetanus jabs’, although these have different purposes.

Why do some people recommend not vaccinating?
There is currently a school of thought that all vaccines (for children or pets) should be avoided for various reasons:

  • No longer needed as disease cases reducing in number. Tetanus has been recognised as a serious illness for thousands of years (recorded in Egypt in 1550BC), but in the modern world the disease and death from it is a lot less common.
    *This is partially due to increased hygiene and knowledge of wound care; however, it is also due to vaccination and there are numerous instances where diseases increase in number when vaccination stops (e.g. polio).
  • Vaccinations don’t always work anyway
    *This is true. In general, vaccinations tend to work in only 98% of cases i.e. there will always be some animals that are vaccinated but are still at risk of the disease. However, because it works in most animals, any individual animal is much less likely to get the disease than if it was not vaccinated.
    *Even if a vaccinated horse does get the disease, it is more likely to respond to treatment than one that hasn’t been vaccinated i.e. it is more likely to live.
  • Vaccinations have side-effects.
    *This is also true. However, generally the side-effects are much milder than the symptoms of the disease and this is particularly true for diseases like tetanus which causes extreme pain and death.
    *Side-effects in horses include lumps and soreness at the injection site (lasting hours/days). Uncommon reactions include general malaise (feeling down, lasting several days) or, rarely, an allergic reaction (usually occurs within minutes or hours of the injection).
  • ‘Nosodes’ are safer and better. A nosode is a homeopathic vaccine.
    *No scientific trials have shown that these protect the horse against disease, either by increasing the horse’s antibody levels or by other methods. Registration of a drug (including vaccines) means that proof of effectiveness must be provided, and this may be one of the reasons why nosodes aren’t registered. A horse is at risk of getting tetanus if it is not vaccinated with an effective product.

To Sum Up:

  • Should you vaccinate your horse for tetanus?                                  Yes
  • Should you vaccinate yourself for tetanus?                                       Yes
  • Does vaccination mean you don’t have to treat wounds?               No
  • Will tetanus vaccination be recorded on my horse’s passport?  Yes
  • Does vaccination with anti-toxin provide long-term protection?   No
  • Does vaccination with toxoid provide long-term protection?        Yes
  • Are vaccinations 100% effective and 100% safe?                             No
  • Is the disease a lot worse than the vaccination side-effects?     Yes

Are you yourself vaccinated? Don’t like needles? You won’t like having tetanus even more! When I was a vet student, we were shown a black and white video of a man in agony from tetanic spasms. Believe me, a needle is nothing in comparison!

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