Strangles in Horses

Early signs, why you isolate straight away, and when to call your vet.

Quick Answer

Strangles is a highly infectious bacterial disease of the upper airway and the lymph nodes of the head and neck, and it does not infect people.
A raised temperature is often the first sign, so if your horse has a fever, a thick nasal discharge, a swollen jaw or dullness, isolate it and call your vet straight away.
If your horse has difficulty breathing or swallowing, or will not eat or drink, call your vet immediately because swollen glands can restrict the airway.
Do not wait for a test result before isolating, and do not release a horse from isolation just because its signs have gone.
Treatment is vet-led, with nursing and supportive care, and your vet will advise on how long a horse must stay isolated.

Strangles in horses can start quietly, with little more than a raised temperature. By the time swollen glands or a thick nasal discharge appear, other horses on the yard may already be exposed.

This guide explains the signs, how the infection spreads, what to do if you suspect it and how to lower the risk. It is general information, not a diagnosis. Your vet must confirm what is going on and plan your horse's care.

Two horses, a bay and a chestnut, look out from a stable window, where strangles in horses can spread by contact and shared equipment

What is strangles in horses?

Strangles is caused by a bacterium called Streptococcus equi. It is not a virus. It affects the upper respiratory tract and the lymph nodes of the head and neck.

The name comes from the way swollen lymph nodes can restrict the airway. Any horse can get it, whatever its age, breed, health or value.

It can happen in well-run yards, and an outbreak does not by itself mean poor management. World Horse Welfare says strangles cannot infect people and only affects equines.

How strangles in horses spreads

Contact and shared surfaces

The infection passes by direct contact between horses. It also spreads through stables, gates, feed buckets, hay piles, tack, lorries and trailers. People's hands, clothing and shoes can carry it too.

Unlike flu, strangles does not generally spread far through the air, according to the EIDS information sheet. The bacteria can survive in water for several weeks, according to the BHS, so shared troughs and buckets are a major route. BEVA also notes that flies can carry infection.

A grey horse looks out from a stall in a long wooden stable block, a setting where strangles in horses can spread through shared surfaces

Horses that show few signs

Some horses show only mild signs, such as a slight nasal discharge, a brief rise in temperature or a slight loss of appetite. They can still pass the infection on. Horses may also shed bacteria before obvious signs appear.

Carriers

After infection, the BHS says that on average around one in ten horses becomes a carrier, though this can vary between outbreaks. A carrier looks healthy but harbours the bacteria, usually in the guttural pouches. It can shed them intermittently for months or even years, especially under stress.

The HBLB Codes of Practice say carriers are probably the most important reason infection persists on a premises. Only a vet can identify carriers, and they can be treated.

Who is most at risk

Young, elderly and previously unexposed horses are the most susceptible. The risk rises when horses mix closely, for example during transport, at events or in shared yard spaces.

Signs of strangles in horses

The BHS says a raised temperature, above 38.5°C or a significant change from normal for your horse, is often the first sign. Its advice is "hot before snot". Knowing your horse's normal temperature helps you spot a change early.

A raised temperature.
Thick, often yellow nasal discharge.
Swelling around the jaw, head or neck, which can burst and release thick, yellow pus.
Dullness, or a lowered head and neck.
Reduced appetite, not drinking, or difficulty swallowing.
A cough.

Not every horse shows the same signs. In some, a nasal discharge without swollen glands is all that is seen. Mild signs can be mistaken for other respiratory problems, so treat any suspicious signs seriously.

Emergency: Contact a Vet Immediately If…

Your horse has difficulty breathing, or breathing looks laboured.
Your horse has difficulty swallowing, eating or drinking.
Your horse is not eating or drinking.

Call your vet or the nearest out-of-hours emergency vet straight away. Swollen glands can restrict the airway, and strangles can become fatal if the airway is blocked or the infection spreads to other parts of the body. Keep the horse isolated while you wait.

When to Contact Your Vet

Your horse has a raised temperature, thick nasal discharge, swollen glands, dullness or reduced appetite.
Your horse shows only mild signs. These can still spread infection, so isolate as a precaution and phone your vet.
Your horse has been in contact with a suspected case in the last three weeks.

Call as soon as you have concerns, and do not wait for a diagnosis before you isolate the horse.

What to do if you suspect strangles

Do not wait for strangles to be confirmed before you isolate. Waiting gives the bacteria time to spread.

The BHS first-response list is:

Isolate the affected horse straight away.
Tell your yard owner.
Stop all horses moving on or off the yard.
Call your vet.
Take each horse's temperature twice daily.
Tell the people and places your horse has contacted in the last three weeks, such as other yards, venues, vets, farriers, physios and transporters.

The BHS and EIDS describe a traffic-light system. Red horses are suspected or confirmed cases, with their own equipment, buckets and water, and they are attended last. Amber horses have been in contact with red horses in the last three weeks but show no signs. Green horses have had no such contact and are attended first.

Do not share water, buckets, tack or grooming kit between horses of unknown status. BEVA advises cleaning contaminated equipment with detergent, then disinfecting it. Visitors such as farriers and vets should wear protective clothing or change before the next yard.

Telling others and reporting

The HBLB Codes of Practice say there is no legal requirement to notify strangles in the UK, though it is advisable to inform the national breeders' associations. Strangles is not on the GOV.UK list of notifiable horse diseases.

Racehorse trainers are different. Under the Rules of Racing they must report likely or confirmed strangles among horses in training to the British Horseracing Authority.

Rules can change, so ask your vet to check the current position. Warning other yards promptly is a vital part of the response, and yards that do so deserve support.

How vets diagnose and treat strangles in horses

Your vet will examine your horse, take its temperature and take samples. These can include swabs from nasal discharge or a burst abscess, guttural pouch endoscopy and blood tests for antibodies.

Redwings says endoscopy is the gold standard for established infection or recovery. Swabbing is less reliable, and repeat tests are often needed. A blood test shows antibodies, not live bacteria, so a positive result alone does not prove active infection.

Strangles cannot be "cured" once a horse is infected, according to Redwings. Recovery mainly involves nursing and supportive care under veterinary advice, in isolation. Your vet may prescribe medication to help with severity or complications.

Regular warm poultices can encourage abscesses to burst, and soaked feed and forage can make eating easier. Do this only as your vet guides you.

Recovery and carriers

Most horses recover. Sources quote anything between two or three weeks and six weeks for recovery, so your vet will advise on your horse.

A horse can still shed the bacteria after its signs clear. The BHS says it can spread bacteria for around six weeks after signs have gone, sometimes longer. Only end-of-outbreak testing, arranged with your vet, shows when a horse is safe to leave isolation.

Complications can include pus retained in the guttural pouch, infection lasting months, and a form called "bastard strangles", where infection spreads beyond the airway. Vets can check and treat carriers. Carriers need a second test two weeks later to confirm they are clear.

Preventing strangles in horses

Quarantine new arrivals and check their temperature daily. Sources quote between two and four weeks, so ask your vet how long.
Ask your vet about strangles testing for new arrivals.
Take your own water to events, avoid nose-to-nose contact with other horses, and check that stabling has been disinfected.
Clean and disinfect shared vehicles between trips.
Take your horse's temperature regularly, especially after events.

A strangles vaccine is available in the UK. It supports immunity and can reduce risk and severity, but it should be used alongside biosecurity, not instead of it. Whether it suits your horse is a decision to make with your vet. Our guide to Horse Vaccinations: What to Discuss With Your Vet covers the wider conversation.

How Pet Med Direct Can Help

Suspected strangles is a situation for your vet first. Please isolate your horse and call them before ordering anything.

Once your vet has advised, our equine range has everyday horse care items. If your vet has prescribed a medicine, our guide to how pet prescriptions work explains the process.

Some pet medicines require a valid veterinary prescription. Pet Med Direct can only supply prescription medicines after the prescription has been checked. Always follow your vet's advice and the directions on the medicine label.

Frequently Asked Questions

Is strangles airborne?

Not in the way flu is. Strangles spreads through direct contact and contaminated surfaces, and the bacteria generally do not spread far through the air.

Can people catch strangles from horses?

World Horse Welfare says strangles cannot infect humans and only affects equines. Hygiene still matters, because hands, clothing and shoes can carry the bacteria between horses.

Is strangles notifiable in the UK?

The HBLB Codes of Practice say there is no legal requirement to notify strangles in the UK, though racehorse trainers must report it to the BHA. Owners are strongly encouraged to tell neighbouring yards.

How long can a horse spread strangles?

The BHS says around six weeks after signs have gone, sometimes longer. Carriers can shed for months or years. Your vet will advise on when testing is needed.

When should I take my horse's temperature?

Take it regularly so you know what is normal for your horse. In an outbreak, horses in contact need checking twice daily. The BHS says above 38.5°C is a warning sign.

How long does it take for signs to appear?

Sources vary widely. They quote anything from a few days to about four weeks after exposure. This is why horses that have been in contact with a case need monitoring.

Related Equine Health Guides

Sources and Further Reading

This article was researched from the sources listed above. It is general information for horse owners and is not a substitute for advice from your own vet.

Prefer Pet Med Direct in Google Search

Choose Pet Med Direct as a preferred source on Google to help you find more of our pet health, medicine and prescription information in Google Search.

← Back to Equine Health Hub

Need pet products or prescription medicines? Visit the Pet Med Direct shop.

Shop Pet Med Direct

This article is for informational purposes only and does not constitute veterinary advice.
If you are concerned about your horse’s health, please consult a qualified veterinarian.