Strangles in horses: symptoms, spread and what a yard should do

The first sign of strangles in horses is usually a fever, a resting temperature above 38.5°C, often before any nasal discharge. Thick discharge, swollen glands under the jaw and abscesses follow. It spreads by contact, shared kit and people’s hands, and is manageable with isolation and your vet.

Strangles is the most common infectious disease of horses in the UK, and it carries a stigma it doesn’t deserve. People hide it, yards whisper about it, and owners feel judged. None of that helps the horses. As Redwings puts it in its strangles guide, “it is not a disease of poor welfare”. Any horse on any yard can get it.

This post covers the first signs and the classic ones, how it spreads, how long it lasts, the traffic light system yards use to contain it, carriers, treatment, the vaccine, and whether you can catch it yourself.

What are the first signs of strangles in horses?

Fever, almost always. Redwings’ guide to strangles lists the earliest signs as a resting temperature above 38.5°C and the horse being off colour.

The detail that makes this so useful is the timing. According to the Redwings strangles pack (PDF), a horse normally develops a fever two to three days before it becomes infectious. By the time you see nasal discharge, it may already have been passing bacteria on for several days.

So the thermometer is your early warning, not the tissue in your pocket. If you know your horse’s own resting temperature, a reading that is up on its normal stands out straight away. Our guide to normal horse temperature, pulse and respiration covers how to take it and how to build that baseline.

Redwings recommends taking temperatures twice a day for three weeks if you think a horse may have been put at risk, and regular resting readings after any event.

What are the symptoms of strangles in horses?

As the disease takes hold, Redwings lists these signs:

• Fever and dullness
• Thick, discoloured nasal discharge
• Swollen lymph nodes under the jaw, behind the jaw or below the ears
• Abscesses in those places, which burst and release thick pus
• Trouble swallowing, loss of appetite, or reluctance to stretch the head out, all signs of a sore throat
• Difficulty breathing, which is where the name comes from
• A cough sometimes, though it is less common than the other signs

Not every case looks like the textbook. Some horses only have a mild, short fever, a slight loss of appetite or a bit of nasal discharge. You probably wouldn’t think of strangles at all. Those horses can still infect others, and the next horse may be much sicker, so Redwings advises isolating as a precaution until a vet has ruled it out.

Ring your vet if a horse has a fever with any of these signs, and treat it as urgent if it is struggling to breathe or can’t swallow. Strangles is fatal in up to 10% of cases, Redwings says, and complications develop in up to 20%, so it always needs a vet, even when it looks mild.

How does strangles spread between horses?

Strangles is caused by a bacterium, Streptococcus equi, not a virus. Redwings says it spreads most easily by direct contact between horses, and the pack adds that even a brief touch is enough.

It also travels indirectly, and on a livery yard this is where most of the risk sits:

• Water. Shared troughs and tanks are especially high risk. Redwings found the bacteria can live for over three weeks in the water at the bottom of a bucket.
• Equipment. Buckets, haynets, tack, grooming kit, rugs and shared transport.
• People. Hands, clothes and boots. The bacteria have been shown to survive in the tread of a boot sole for more than two weeks.
• Places. Stables, field shelters and paddocks.

It is not airborne, although a horse can cough or snort infected material several feet. Strangles survives longest in cool, damp conditions, which is worth remembering through a British winter.

How long does strangles last in horses?

Signs normally appear 3 to 4 days after contact, according to the Redwings pack, but they have taken up to 21 days. That three week window is why isolation periods are three weeks long.

Redwings says many horses are very ill but start to feel better after two to three weeks. Feeling better is not the same as being clear: horses are likely to stay infectious for several weeks after they recover, and only veterinary testing tells you when isolation can end.

This table puts the Redwings timeline together with what to do at each point.

What should a livery yard do if a horse has strangles?

Don’t panic, but act straight away. The Redwings pack advises stopping all horse movements on and off the yard and isolating as a precaution while you speak to your vet and arrange testing. If the tests come back negative, isolation is easy to lift.

Once strangles is confirmed, Redwings recommends working with your vet on a traffic light system, which works even on a big yard:

• Red zone. Strict isolation for horses with signs of strangles or a positive test.
• Amber zone. Equally strict isolation for horses that may have had direct or indirect contact with a sick horse in the last three weeks, and may be incubating it.
• Green zone. Normal management with close monitoring, for horses not thought to have been in contact with any sick or at risk horse for at least three weeks.

A few practical points from the same guidance:

• Care for horses in order: green, then amber, then red. Better still, have different people look after the green horses so they never go near the isolation areas.
• Take amber horses’ temperatures daily, ideally twice a day, so a horse that develops a fever can move to red before it sheds large numbers of bacteria.
• Amber can become green if every horse in it shows no sign of disease for three weeks after its last possible contact, or tests negative, and your vet agrees.
• Cast the net wide. It is easier to put the whole yard into isolation at the start and release horses as you’re confident they weren’t at risk than to chase the disease round the yard.

And talk about it. The pack is clear that speaking up is part of a good response, not a confession. In Redwings’ own survey, more than 40% of people who had been through an outbreak rated how it was managed 10 out of 10. The HBLB Codes of Practice note that strangles is endemic in the UK horse population. It is a disease of horses moving around, not of bad yards.

To prevent the next one, Redwings suggests 2 to 3 weeks of quarantine for new arrivals, ideally with testing, and a written yard agreement covering new horses, events and isolation. It publishes a template on its advice page for yard managers.

What is a strangles carrier?

A carrier is a horse that has had strangles, looks perfectly healthy, and still has live bacteria in its guttural pouches, the two air sacs at the back of the throat. Redwings says around one in ten infected horses becomes a carrier, sometimes for months or years.

Carriers can shed bacteria now and again, more often under stress such as travelling, moving yards or meeting new horses. Redwings says carriers are believed to be the most common source of outbreaks, which is why strangles can seem to appear out of nowhere.

The good news is that carriers can be found and treated. A vet can look inside the pouches with an endoscope, take samples, and wash out any hardened pus, known as chondroids. Redwings calls guttural pouch endoscopy the gold standard test for horses that are recovering. Swabs are less reliable and need at least three negative results, taken a week apart. Blood tests can show a horse has met the bacteria, and are useful for screening new arrivals, but a positive usually needs further tests.

The best time to stop a horse becoming a carrier is as it recovers, so ask your vet about testing before any horse comes out of isolation.

How is strangles in horses treated?

Redwings is honest that strangles can’t be cured once a horse is infected. It has to run its course, and the job is to get your vet involved early and keep the horse comfortable while it does.

Your vet decides on medication. The Redwings pack notes that vets usually prescribe an anti-inflammatory for pain, fever and swelling, and that antibiotics are often ineffective in strangles, so it is the vet’s call whether and when to use them.

Good nursing makes a real difference:

• A deep, comfortable bed in a sheltered, well ventilated stable
• Soaked feed and forage that is easy to swallow, which also helps water intake. Keep an eye on how much the horse is drinking, as a horse with a sore throat may drink less than its normal amount
• Warm compresses on developing abscesses to help them come to a head and burst. Never squeeze or pierce an abscess yourself
• Gentle bathing of a burst abscess to keep it clean while it drains
• Something to do. Isolation is hard on a horse, and a view of other horses, slow feeders and multiple feeding points help as it starts to feel better

Is there a strangles vaccine for horses?

Yes. Redwings says strangles vaccines are available and can reduce the chance of a horse becoming infected or reduce how ill it gets. The pack adds that we can’t yet protect horses against strangles as well as we can against equine flu.

So a vaccine is something to use alongside hygiene, quarantine and temperature checks, never instead of them. Your vet is the right person to advise on current products and whether one suits your horse and how much it travels.

Can humans catch strangles?

The MSD Veterinary Manual describes the bacterium as highly host-adapted, producing disease only in horses, donkeys and mules.

The part people play is as the delivery service. Hands, sleeves and boot treads move strangles between stables more easily than horses do on a well run yard. Wash or sanitise your hands between horses, keep separate kit for an isolated horse, and change or cover clothes and boots before you go back to the others.

Where the technology fits

Strangles is managed with a thermometer, a vet, a sensible isolation plan and people willing to talk. An app does none of the hard part. Here is what Stride does and does not do.

There is no temperature field. You can’t enter a reading as a number, there is no fever alert, and nothing warns other owners on your yard. What you can do is write each reading in a note on the horse. Notes are dated and land on the horse’s health timeline, so 38.9°C, 7am twice a day for three weeks is a record your vet can scroll through.

Observations cover several of the signs. The fixed list includes nasal discharge, cough, off food and not drinking, each with a mild, moderate or marked severity, and they appear on the same timeline.

Vet records can hold the paperwork. A vet record or a note can carry photos and PDF attachments, so a lab result or a scope report can sit with the visit it belongs to.

Reminders are typed, including vet and vaccination, each with a due date. That covers a booked retest or the next dose of a vaccine course.

You can share a horse with someone else. An owner can invite a person by email to view a horse, as a viewer, vet, farrier or trainer. They need a Stride account with that email. Pro shares each horse with one person and Elite with as many as you like.

What it doesn’t do: there are no yard-wide isolation zones, no red, amber and green lists, no contact tracing, and no way to see other owners’ horses unless they share them with you.

If you take one thing from this: know your horse’s normal temperature now, and take it every day for a week after it has mixed with horses from elsewhere. Fever comes first, usually before a horse is infectious, and catching it then is the difference between one horse in isolation and a whole yard on lockdown.