Tetanus

Disclaimer: The following is only general information. If you believe that your horse has a problem please call your veterinarian as soon as possible.

Tetanus is a neurological disease affecting the muscles, through the central nervous system. The nervous system is affected by tetanus toxins (poison), produced by Clostridium tetani bacteria.

These bacterial spores are found in the soil, faeces and even on our skin, however when they pass the skin barrier, through a wound, the spores germinate and start producing tetanospasmin toxin, which is a powerful biological poison. The toxins then migrate to the central nervous system (spinal cord, brain and peripheral nerves). The toxin then attaches itself to the ends of the motor nerves, blocking nerve impulses to the muscles. This leads to spasms, contractions, seizures and, in most cases, death.

This disease is found throughout the world and affects humans as well as all domestic animals (except cats). Horses are extremely susceptible and in parts of the world where immunisation rates are low the disease is common.

The incubation period (the time between becoming infected and showing signs), is usually between 3 to 14 days with the average being 8 days. In a small number of cases it can take several months.

A horse that contracts Tetanus may only have a 20% chance of surviving.

This is a preventable disease, with properly delivered immunisation giving virtually 100% immunity.

Signs

The two most common forms of this disease are Generalised Tetanus and Neonatal Tetanus. Neonatal Tetanus is a form of Generalised Tetanus that occurs in newborn foals – both show similar signs.

Stiff-legged gait

The tail may be held out stiffly with the ears pricked

The third eyelid will partially cover the eye

The mouth will become stiff (lock-jaw), which will make eating difficult

Drooling with a mixture of food and saliva

Will be sensitive to light and movement near the eye – a hand moved quickly near the horse’s eye will usually result in the eye rolling back, with only the ‘whites’ showing

Stiffness and paralysis will progress to all the muscles

Horse may fall over and not be able to get up

Spasms, contraction and seizures will follow

Your veterinarian will only be able to diagnose this disease by looking for the clinical signs. If you live in a country where immunisation rates are high, then your veterinarian may only ever see one or two cases in his or her entire working life. This is good news, however the downside may be that they can miss the very early stages of the disease.

Cause

Clostridium tetani bacterial spores exist everywhere in our environment, however they will only start mutiplying and releasing the tetanus toxins (poisons), which cause Tetanus, if they enter the body of an unimmunised horse.

The main entry points are:

Any injury that breaks the skin barrier (causes bleeding)

Puncture wounds are particularly dangerous as they provide the ideal environment for the bacteria to multiply

Punctured hooves and leg injuries have a high risk, because they are close to or in contact with soil and faeces

The umbilical stump of new born foals, when the mare has not been immunised and particularly when an unsterilized instrument is used to cut the cord

Treatment

Injecting antitoxin under the skin

If you know that your horse or pony is not immunised or his immunisation may have lapsed or you don’t know your horse’s immunisation history, then the following situations will require action.

Injured but without signs of Tetanus (injuries include punctures, cuts and abrasions)

Call your vet immediately and follow instructions

Take your horse to a clean, dry place and clean the wounds thoroughly with a diluted iodine solution – if the wounds or punctures are deep you may need to wait for your vet to sedate your horse before flushing them out

After cleaning the wounds your vet may inject 1500 units (1 syringe) of Tetanus Antitoxin (Equivac-TAT) under the skin, on one side of your horse neck and then inject 1ml of Tetanus Vaccine (Equivac-T) into the muscle, on the other side of the neck

You or your vet will need to inject another dose of Equivac-T four weeks later for longer-lasting immunity

Depending when the injury occurred, your vet may, or may not, give your horse a Penicillin injection

If you found the injury and acted quickly your horse is unlikely to develop Tetanus, however you should closely monitor your horse for the next two weeks

If the injury is easy to clean, you found it quickly and you know how to give injections into the muscle, then you may be able to handle this care by following your veterinarian’s instructions. Ask your vet how to sterilise your horse’s neck before injecting. Iodine solution may not be the best.

With signs of Tetanus

Call your vet immediately and follow instructions

Calmly take your horse to a dry, clean place away from other horses – this is a disease that affects your horse’s nervous system so a quiet, calm environment is essential

Assist your vet to locate the injury, if possible, and clean it thoroughly, with a diluted iodine solution

Your vet will give the fast acting Tetanus Antitoxin (Equivac-TAT) under the skin, on one side of your horse’s neck, and the slower acting Tetanus Vaccine (Equivac-T) into the muscle, on the other side of the neck (see dosages above)

Your vet will then give your horse a Penicillin injection

Your vet will also give a muscle relaxant to minimise the spasms

An ongoing course of Penicillin injections will be prescribed as well as muscle relaxants when required

You will then need to provide intensive nursing care to your horse

A darkened, quiet stable is the best environment, but make sure that the bedding is super thick, kept very clean and all potentially dangerous objects are removed – a row of straw bales around the walls can also stop your horse from leg injuries if he spasm or convulses

Chewing will be difficult for your horse, if his jaw stiffens (locks), so make up a bran mash and feed him small amount often

Care will be intensive and long term, while you wait for your horse to regenerate new nerve endings

Prevention

Treatment of an infected horse or foal is difficult, time consuming, very expensive and often unsuccessful, so the message here is,
Immunise! Immunise! Immunise! Immunise! Immunise! Immunise!

Initially inject Tetanus Antitoxin (Equivac-TAT) into the muscle (sterilise the area)

Two weeks later inject the Tetanus Vaccine (Equivac-T) into the muscle (sterilise the area)

Four weeks later inject another dose of the Tetanus Vaccine (Equivac-T) into the muscle (sterilise the area)

This will give your horse almost full immunity.

In 12 months give a booster shot of Tetanus Vaccine (Equivac-T)

Then repeat your horse’s booster shots every 5 years.

Mares should be given a Tetanus booster a month before foaling – this will give the foal some immunity

Foals should start their immunisation programme at 3 to 4 months

Comment: We prefer to give Tetanus boosters annually, rather than every five years, so that we remember and avoid a lapse in immunity. We also combine it with an annual booster for Strangles, which can be purchased in the one syringe (Equivac 2 in 1). See the Strangles article in the Health Care menu.
You should also be immunised against Tetanus. Working around horses, soil and faeces makes immunisation a necessity. The good news is, that after your initial immunisation programme is completed, you will only need boosters every ten years.

Myths

Horse’s which have been infected and recovered or been exposed to Tetanus develop a natural immunity – WRONG

Immunising horses leads to poor performance – WRONG