How to Protect Your Horse: Tetanus in Horses Explained

Tetanus in horses is a disease of the nervous system caused by a bacterial toxin, and it is one of the few serious equine diseases that a routine vaccine prevents almost completely. Once it takes hold it is very often fatal: in the largest study of the disease in Europe, covering 176 equids treated at 20 university and referral hospitals between 2000 and 2014, 68.4% of the adult horses did not survive. This guide explains how tetanus gets in, the early signs to watch for, what treatment involves, and the UK vaccine schedule taken from the vaccine datasheets themselves, so you know exactly where your horse stands.

What Is Tetanus in Horses?

Tetanus, often called lockjaw, is caused by a toxin produced by the bacterium Clostridium tetani. The British Horse Society describes it as a non-contagious disease caused by a bacterium commonly found in soil, and Horse & Hound’s vet library, approved by Karen Coumbe MRCVS, notes that the spores are widespread in dust, manure and soil. A horse cannot catch tetanus from another horse. Each case starts when spores get into that horse’s own tissues, usually through a wound.

The spores need low-oxygen conditions to germinate. Once they do, the bacteria release a neurotoxin that, as MSD Animal Health explains, travels up the nerves to the spinal cord and blocks the inhibitory signals that normally let muscles relax. The result is muscle stuck in contraction, and a horse that spasms violently when anything startles it. For a short reference summary, see our equine tetanus (lockjaw) profile.

MSD Animal Health also notes that horses and people are particularly sensitive to the toxin, and that both the bacterium in the soil and the disease itself are more common in warmer parts of the world. That is worth knowing for readers in South Africa, but it does not make the UK safe: Horse & Hound’s vet library points out that tetanus is more common in some areas of the country than others.

How Horses Get Tetanus

Any break in the skin can let spores in, but some wounds carry far more risk than others. Horse & Hound’s vet library puts it plainly: a large, cleanish cut is a lower tetanus risk than a small puncture wound, and the biggest danger is a deep, festering wound with dead tissue and pus that is not exposed to fresh air.

The Most Common Entry Points

The European multicentre study by van Galen and colleagues (Journal of Veterinary Emergency and Critical Care, 2017, PMID 28960717) recorded where each infection started. In adult horses the most common entry sites were:

• Castration wounds. Gelding is one of the most routine operations a colt will have (see how castration with a gelding knife is carried out), and Horse & Hound’s vet library also lists castration wounds among the high-risk situations.
• Hoof abscesses. An abscess inside the hoof is exactly the sealed, airless pocket the spores need. The BHS names foot abscesses and deep puncture wounds as especially vulnerable, and our guide to treating a hoof abscess covers the rest of the care.
• Wounds, particularly the ones on H&H’s high-risk list: puncture wounds contaminated with soil, such as kicks, and stake wounds, which are often deep and heavily contaminated.

In foals the pattern was different: umbilical cord infections and wounds were the main entry sites. H&H’s list adds infections at foaling, and MSD Animal Health names retained foetal membranes in the mare as a route of entry.

When There Is No Wound to Find

Not every case has an obvious cause. MSD Animal Health notes that the penetrating wound may have gone undetected, or may even have fully healed, by the time signs appear. The BHS describes a second route: the bacterium can live harmlessly in a healthy horse’s gut and be shed in droppings, and a horse with a damaged gut that eats contaminated soil or faeces may become infected. A horse with no visible injury can still develop tetanus, which is why vaccination, not wound-watching, is the real protection.

Signs of Tetanus in Horses

Tetanus signs build over hours to days, and at first they are easy to mistake for general stiffness or colic. In van Galen’s European cases, stiffness was the most common first sign. In an earlier Canadian series of 20 horses (Green et al., Journal of Veterinary Internal Medicine, 1994, PMID 8046676), heightened sensitivity to stimuli and prolapse of the third eyelid were the most common signs.

Early Symptoms of Tetanus in Horses

The early signs described by Horse & Hound’s vet library and the BHS include:

• Stiffness and a stiff gait, with reluctance to move or turn
• Unusual sensitivity to sound, touch and movement: a horse that jumps at a dropped bucket or flinches when handled
• The third eyelid flicking across the eye, especially when the horse is startled. MSD Animal Health notes it can be exaggerated by tapping the horse lightly on the side of the face
• Ears held rigidly upright and the top of the tail sticking out stiffly
• A worried expression, with the eyelids drawn back and the nostrils flared
• Difficulty opening the mouth or chewing, with partly chewed hay held in the mouth
• Food and water coming back down the nostrils, and drooling, as swallowing becomes harder
• Signs of colic

Any of these in a horse that has had a wound, a hoof abscess, surgery or a foaling in recent weeks should be treated as an emergency. The BHS is clear that early treatment is essential: call your vet immediately.

Advanced Signs

As the disease progresses, the stiffness spreads and even minor stimulation sets off spasms that grow stronger and more frequent, according to MSD Animal Health, which describes the braced, “rocking horse” stance of an affected horse. The complications van Galen and colleagues recorded in hospitalised horses show how the whole body is affected:

• Difficulty swallowing (dysphagia) and difficulty breathing (dyspnoea)
• Going down and being unable to rise (recumbency)
• High body temperature and seizures
• Hyperlipaemia, a dangerous build-up of fat in the blood when a horse stops eating
• Gut impactions and difficulty passing urine
• Spasm of the larynx

In the final stages the BHS describes severe spasms and seizures leading to collapse, and death from respiratory or heart failure.

How Soon After a Wound Do Signs Appear?

The gap between injury and signs varies widely. In Green’s Ontario series, horses had been injured an average of 9 days before signs appeared, with a range of 2 to 21 days. In a Belgian series of 31 equids (van Galen et al., Tijdschrift voor Diergeneeskunde, 2008, PMID 18615902) the gap ranged from 2 days to 2 months. The BHS gives 7 to 21 days as the usual window, and Horse & Hound’s vet library notes that the shorter the incubation, the more serious the infection tends to be. The practical point: a wound you have forgotten about can still be the cause weeks later.

Diagnosing Tetanus in Horses

There is no quick yard-side test to wait for. Horse & Hound’s vet library says diagnosis is made on the history and the clinical signs, and that it is often all too obvious: a dirty wound on an unvaccinated horse. MSD Animal Health adds that if the wound can be found, the bacterium can sometimes be shown in stained smears or by culture. Treatment does not wait for either.

Early cases can look like other problems, and H&H notes that colic, pneumonia and laminitis can confuse the picture. Trembling and spasm have other causes too: severe low blood calcium (hypocalcaemia) produces tetanic muscle spasms and “thumps”, and hyperkalaemic periodic paralysis (HYPP), an inherited disorder in Quarter Horse lines descended from the stallion Impressive, causes episodes of trembling and weakness. Our guides to ataxia in horses and wobbler syndrome explain how a vet separates true incoordination from the rigid stiffness of tetanus.

Treating Tetanus in Horses

Treatment is intensive, expensive and not always successful. It has four jobs: neutralise toxin that is still circulating, kill the bacteria so they stop making more, control the spasms, and keep the horse fed, watered and safe while the nervous system recovers. Horse & Hound’s vet library and the BHS both describe large doses of tetanus antitoxin given alongside antibiotics, sedatives and muscle relaxants.

Tetanus Antitoxin

Antitoxin is a ready-made antibody, produced in horses, that binds toxin in the bloodstream. It cannot recall toxin that has already reached the nerves, which is why speed matters: MSD Animal Health describes its job as combating the circulating neurotoxin. The UK-authorised product, Tetanus Antitoxin Behring, states in its datasheet (VMD SPC, revised February 2026) that protection begins 1 to 4 hours after intravenous or intramuscular injection in horses and lasts 2 to 3 weeks.

How much to give is your vet’s decision. In van Galen’s European cases (Part 2, PMID 28960891), survival did not differ significantly between antitoxin doses, although there was a trend towards better survival at higher intravenous doses, and the authors called for further study.

Antibiotics and Wound Care

The source of the toxin has to be dealt with. The European cases were managed with wound debridement (cutting away dead and infected tissue) and antimicrobial treatment, and every horse in Green’s Ontario series received penicillin by injection. Which antibiotic, and for how long, is for your vet to decide.

Controlling the Spasms

Sedatives and muscle relaxants reduce the spasms and the distress they cause. In Green’s series, the horses that responded to phenothiazine tranquillisers, the drug family that includes acepromazine, had the best outlook. Seizure control, pain relief and anti-inflammatory drugs were all part of the European hospital treatment.

Nursing Care

Nursing is where owners and yard staff make the biggest difference. Because noise, light and handling set off spasms, a quiet, dim stable and calm, minimal handling mean fewer episodes. The BHS advises placing food at a comfortable height if the horse can still eat, because a stiff horse struggles to lower its head. MSD Animal Health notes that fluid therapy and slings may be needed. In the European study, a horse still drinking voluntarily and eating soft food was among the strongest signs it would survive.

When Euthanasia Is the Kinder Choice

Horse & Hound’s vet library is frank: if a tetanus case is unable to stand, it is kindest for the horse to be euthanised, since the chance of recovery is remote. The BHS says the same of advanced cases where recovery is unlikely. Your vet will talk this through with you.

Can a Horse Survive Tetanus? Prognosis and Recovery

Some do, but the odds are poor. The published hospital figures:

• van Galen et al., 2017 (176 equids, 20 European hospitals including the University of Liverpool’s Philip Leverhulme Equine Hospital, 2000 to 2014): 68.4% of adult horses (106 of 155) and 66.7% of foals (14 of 21) did not survive. Those figures include horses euthanised for financial reasons: of all 120 non-survivors, 21 died, 22 were euthanised for financial reasons and the rest were euthanised on humane grounds. The financial cases were left out only of the paper’s comparison of survivors with non-survivors, not out of the death rate.
• Green et al., 1994 (20 horses, Ontario Veterinary College, 1970 to 1990): 75% died.
• van Galen et al., 2008 (31 equids, University of Liège, 1991 to 2006): 32% survived, and every non-survivor died within 8 days of the first signs.

The same studies show what tips the balance. In the European prognostic analysis, survival in adults was linked to still standing, normal gut sounds and droppings, drinking voluntarily, eating soft or normal food, lower heart and breathing rates and a mild grade of disease. Death was linked to not eating, difficulty swallowing, difficulty breathing, and going down or having seizures in hospital. Green’s series found the best outlook in horses that had been vaccinated before the injury, responded to tranquillisers and did not go down quickly (within 24 to 48 hours). In the Belgian series, younger animals were affected more often and more severely.

Survivors Are Not Immune

Recovering from tetanus does not make a horse immune. The New Zealand and Australian prophylaxis panel (Lovett et al., New Zealand Veterinary Journal, 2024, PMID 38910032) states that survivors of clinical tetanus must still receive the full primary vaccination course.

Tetanus Vaccine for Horses: The UK Schedule

Vaccination prevents nearly everything described above. The vaccine is a toxoid: inactivated toxin that trains the immune system without causing disease. Horse & Hound’s vet library calls it safe, effective and inexpensive, and the Lovett panel describes it as highly effective at preventing disease, while tetanus in unvaccinated populations carries high mortality.

The exact schedule depends on the product your vet uses, and the datasheet (the Summary of Product Characteristics, or SPC, held by the Veterinary Medicines Directorate) is the authority. These are the current UK datasheets for three widely used tetanus-containing vaccines:

Vaccine (datasheet)	Primary course	First tetanus booster	Then
Equilis Te, tetanus only (revised Nov 2023)	Two doses 4 weeks apart, from 6 months of age	Not later than 17 months after the primary course	Maximum interval of 2 years
Equilis Prequenza Te, flu and tetanus (amended Apr 2024)	Two doses 4 weeks apart, from 6 months of age	Not later than 17 months after the primary course	Maximum interval of 2 years for tetanus; flu boosters follow their own, shorter schedule
ProteqFlu-Te, flu and tetanus (amended May 2026)	Two doses 4 to 6 weeks apart, from 5 to 6 months of age	5 months after the primary course	Maximum interval of 2 years for tetanus; flu every year

The BHS summarises a typical programme as two initial injections 28 to 42 days apart, a booster 12 months later, then boosters usually every two years, with the caveat that schedules vary by vaccine. Horse & Hound’s vet library gives two doses four to six weeks apart, then boosters usually every two or three years. Where a general summary and your vaccine’s datasheet differ, follow the datasheet and your vet. Every dose should be recorded in the horse’s passport.

Combined Flu and Tetanus Vaccines

Most horses get their tetanus cover in a combined flu and tetanus injection. Flu immunity is shorter-lived and competition rules demand flu boosters far more often, so the datasheets alternate: ProteqFlu-Te, for example, is given every year for flu, alternating with the flu-only ProteqFlu, while keeping the tetanus component within 2 years. For the BHA, FEI and British competition flu rules, see our guide to horse vaccines in the UK and our equine influenza profile.

What the Research Says About Duration of Immunity

The datasheet intervals are conservative. A Swedish study (Kendall et al., Equine Veterinary Journal, 2016, PMID 26284567) followed horses given Equilis Prequenza Te. After a third dose, antibody levels stayed above the detection limit in 25 of 26 horses at one year, 16 of 16 at two years and 8 of 8 at three years, and the authors concluded protection is likely to last more than 3 years. The Lovett panel now recommends boosters within 5 years for New Zealand and Australia. Neither changes the UK datasheets, but together they explain why a correctly vaccinated horse is so well protected.

If a Booster Has Lapsed

Whether a lapsed horse needs a single booster or a restarted primary course is a datasheet and vet question, and it depends on how long it has been. A Japanese study (Kinoshita et al., Journal of Veterinary Medical Science, 2023, PMID 37258221) found that one revaccination dose was as effective as two, for at least a year, in horses that had not been vaccinated in the previous year. Check the dates in the passport and ring the practice if they have slipped.

Tetanus Vaccine Side Effects

Reactions are uncommon. The Equilis Te datasheet lists injection-site swelling and pain as rare (1 to 10 in every 10,000 horses treated), and fever, lethargy, loss of appetite and hypersensitivity reactions as very rare (fewer than 1 in 10,000). The ProteqFlu-Te datasheet lists injection-site swelling and pain, raised skin temperature, muscle stiffness and raised body temperature as rare. Both say to vaccinate healthy animals only, so tell the vet before the injection if your horse is off colour on the day.

Tetanus Protection for Foals and Pregnant Mares

A foal’s first protection comes from its dam’s colostrum, so the mare’s vaccination matters as much as the foal’s own.

Boosting the Mare Before Foaling

The BHS advises that pregnant mares who are already vaccinated receive a booster 28 to 42 days before foaling, and Horse & Hound’s vet library gives four to six weeks, so that the foal gets maximum antibody protection from the colostrum. The Equilis Te and ProteqFlu-Te datasheets both state the vaccine can be used during pregnancy and lactation. For care through late pregnancy, see our guide to broodmare health.

When Foals Start Their Own Course

The UK datasheets are cautious here. Equilis Te says foals should not be vaccinated before 6 months of age, especially when born to mares revaccinated in the last two months of pregnancy, because maternal antibodies can interfere. For foals at increased risk, or that took in too little colostrum, both Equilis Te and ProteqFlu-Te allow an extra injection at 4 months, followed by the full programme. ProteqFlu-Te’s normal course starts from 5 to 6 months.

The research backs that caution. Wilson et al. (Equine Veterinary Journal, 2001, PMID 11770984) found that 3-month-old foals from vaccinated mares failed to respond to two doses, and recommended that primary vaccination of such foals should not begin before 6 months. A 2026 study of 62 Warmblood foals (Olbrich et al., Equine Veterinary Journal, PMID 42572177) found that the first dose at 180 days produced no detectable antibodies, that antibodies peaked after the second dose and fell back below pre-vaccination levels by 360 days, and that 38.7% of the foals responded weakly. The authors suggest foal schedules, including booster timing, may need optimising. Agree your foal’s timing with your vet, and plan it around weaning so the two stresses do not coincide.

Foals Born Without Protection

Horse & Hound’s vet library advises that foals of unvaccinated mares, or foals that did not get enough colostrum, should be given tetanus antitoxin at birth. It is not a guarantee: the European study includes 2 foals that developed tetanus despite antitoxin at birth.

Tetanus Antitoxin and Serum Hepatitis (Theiler’s Disease)

Antitoxin is made from horse serum, and it carries a small but serious risk. Guglick et al. (Journal of the American Veterinary Medical Association, 1995, PMID 7782247) described 8 horses, all given antitoxin within 12 hours of foaling, of which 7 developed clinical or subclinical hepatitis 48 to 87 days later; one was found dead with the lesions of serum hepatitis. This is Theiler’s disease, and in 2018 Divers et al. (Emerging Infectious Diseases, PMID 29350162) identified a new virus, equine parvovirus-hepatitis, in a horse that died 65 days after tetanus antitoxin and in the antitoxin itself, then reproduced the hepatitis by giving contaminated antitoxin to two horses. Our entry on equine viral hepatitis covers the wider picture. The Tetanus Antitoxin Behring datasheet also warns that repeated doses given at longer intervals can sensitise a horse and lead to hypersensitivity reactions.

That is a reason to keep vaccination up to date so your horse never needs antitoxin. It is not a reason to refuse antitoxin for an unvaccinated horse with a wound, where your vet is weighing a small risk against a disease that more than two in three hospitalised adult horses in the European study did not survive.

What to Do When Your Horse Has a Wound

1. Check the passport. The BHS’s first step is to check your horse’s vaccination status and, if it is not up to date, to call your vet.
2. Leave anything embedded where it is. If your horse steps on a nail or other sharp object, the BHS says not to remove it: let your vet assess the injury first, to avoid causing more harm.
3. Ring the vet about any puncture wound, any wound to the foot and any deep or dirty wound, and tell them the horse’s vaccination dates.
4. Unvaccinated or unknown status: expect antitoxin and the vaccine. Horse & Hound’s vet library says horses that are unvaccinated or of doubtful vaccination status should be given tetanus antitoxin if they have a wound or need surgery, with a vaccination course started straight away. The Equilis Te datasheet confirms it can be given on the same day as MSD’s Tetanus Serum, at a separate site and not mixed, giving passive protection for at least 21 days, although the combination may reduce the vaccine’s own immune response.
5. Correctly vaccinated: the vaccine is doing its job. The Lovett panel concluded that pre-existing immunity protects a correctly vaccinated horse after a wound, abscess or surgery. What decides the need for antitoxin is vaccination status, not how many months have passed since the last dose.

Wound Care and Yard Safety

MSD Animal Health’s prevention advice is practical: manage the environment to prevent wounds, clean stables regularly with a suitable disinfectant, carry out surgery and foaling as cleanly as possible, and turn horses out on clean pasture afterwards. Walk the fields for broken fencing, protruding nails and rusty metal, and keep the yard tidy. For the injuries that most often follow a knock or a kick, our guides to proud flesh, overreach injuries, hoof infections and lymphangitis cover the care in detail.

Tetanus and the People on Your Yard

Tetanus is not passed from horse to person, but Horse & Hound’s vet library notes that the bacteria can infect humans directly and advises that people should be vaccinated too. The NHS lists soil or manure getting into a wound as a risk, and says to check with your GP surgery if you are not sure you have been fully vaccinated. Anyone who mucks out, picks out feet or dresses wounds is working with the same soil and manure as the horse.

Final Thoughts

Tetanus is rare in a correctly vaccinated horse and very dangerous in an unvaccinated one. Keep the passport dates within your vaccine’s datasheet interval, treat every puncture and foot wound as a reason to check those dates, and call the vet at the first sign of stiffness, jumpiness or a flicking third eyelid. A booster costs very little next to the cost, in money and in suffering, of treating a single case.

Frequently Asked Questions