Strangles isn't a notifiable disease to government authorities in the UK, but it's good practice to inform anyone who's had recent contact with your yard so they can monitor their own horses.5
What to do when a horse on your yard has strangles
Whether the strangles outbreak is on your yard or close by, you need to take immediate action.1,2 Vaccination goes hand-in-hand with your biosecurity measures as an essential way to limit the spread of the disease.1,2
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If strangles is suspected, divide horses into three isolation groups as per the traffic light system.2
Move horses with clinical signs of strangles, such as a fever, into the ‘red’ group to minimise risk of transmission to other horses.2
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Vaccinate horses that are healthy, which means they show no clinical signs of strangles or other disease.2
Vaccination helps to reduce the risk of the disease spreading and the severity of disease if they do still develop strangles.1,2
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Stop all horses moving onto or around the yard.3
Use isolation as a precaution for all horses while you speak to your vet and arrange for testing.2,4
After an outbreak, make sure to disinfect stables, paddocks and equipment.3
Stay vigilant for carriers and treat them to resolve persistent infection and prevent new outbreaks.3
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Spot the clinical signs of strangles and take each horse’s temperature at least twice a day.2
As fever is the first clinical sign of infection with strangles, there is time to act with biosecurity measures and vaccination. This is because horses typically become infectious 24-48 hours after fever develop.3,5
Implement the traffic light system when strangles is a danger2
Use this traffic light system to separate horses into groups. This minimises the risk of other horses on the yard
and the surrounding area becoming infected with strangles.2
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Horses in the green group have not been exposed to strangles.2
- These healthy horses can be given the vaccine to provide protection from the spread of the disease.
- If a horse in this group comes into contact with a horse with strangles, they should be moved to the amber group.
- If a horse in this group develops clinical signs of strangles, they should be moved to the red group.
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Horses in the amber group are healthy but potentially exposed to strangles.2
- These horses should be vaccinated, only if they show no clinical signs of strangles after a period of monitoring.
- If a horse in this group develops a fever or other signs of the disease, they should be moved to the red group.
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Horses in the red group have shown clinical signs of strangles.2
- Horses in this group should not be vaccinated until they have recovered.
- Talk to your vet about what supportive care to give these horses until they have fully recovered, which can take several weeks.
- Do not reintroduce a horse to the rest of the yard until you have confirmed the disease is no longer present.
Treating a horse with strangles
Most infected horses recover from strangles with only supportive care. However, this recovery period may take three to six weeks presuming no complications occur.3,5 Often, early treatment of exposed horses revolves around good nursing care to alleviate clinical signs.3 Some vets may prescribe NSAIDs. Antibiotics (such a penicillin) are used selectively, because inappropriate use can interfere with the horse building natural immunity, and prolong the disease.7 Your vet will advise based on your individual case.
An innovative solution for vaccination against
strangles now exists.2,8 Ask your vet
strangles now exists.2,8 Ask your vet
FAQs – Your questions answered
Do I need to notify anyone if a horse on my yard gets strangles? add
Which horses can be vaccinated? add
Vaccination against strangles is highly recommended for:2
- Any horses that frequently travel or mix with others and/or livery yards with mixed ownership, particularly if there are frequent new arrivals
- Premises with regular visiting horses or horses transiting through
- Studs that accept walk-in mares and the mares that visit them
- Equestrian businesses where an outbreak would threaten their commercial viability or have an unacceptable impact
- Horses kept in yards with poor biosecurity
- Horses on a yard where there has been an outbreak nearby
Should I vaccinate young, old or non-competition horses? add
Strangles can affect horses of all ages,9,10 and whilst younger horses may show more severe clinical signs, due to the high risk of serious complications and mortality, all horses can benefit from vaccination against strangles.2,3 Not only does vaccination against strangles provide an individual benefit, but also a collective 'herd immunity' benefit for a whole premises, if a larger group is vaccinated.2 Whilst older or non-competition horses may rarely leave a yard, they are still at risk of strangles from other horses travelling in and out of a premises and also from neighbouring yards, for example when passing other horses out hacking or in nearby fields.2
Can a vaccinated horse become infected? add
No vaccine can claim 100% protection.11 Vaccinated horses can still be infected and transmit strangles to other horses.8 However, if a vaccinated horse does become infected, it is at lower risk of serious disease, with milder clinical signs and fewer complications such as abscesses.8
References add
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Rask E, et al. Animals (Basel). 2025;15(24):3584.
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Rendle D, et al. Equine Vet Educ 2025;37:90–97.
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Boyle et al. J Vet Intern Med. 2018;32:633-647.
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Ivens, P. Vet Times. Available at: https://www.vettimes.co.uk/app/uploads/wp-post-to-pdf-enhanced-cache/1/implementing-biosecurity-in-an-equine-environment.pdf (Accessed July 2026).
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British Horse Society. Available at: https://www.bhs.org.uk/horse-care-and-welfare/health-care-management/horse-health/equine-diseases/strangles/ (Accessed July 2026).
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Your Horse. Available at: https://www.yourhorse.co.uk/news/livery-yard-strangles-vaccination-policy/ (Accessed July 2026).
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Pringle J, et al. J Vet Intern Med. 2020;34(1):294–299.
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Strangvac SPC.
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National Equine Welfare Council. Available at: https://newc.co.uk/advice_articles/strangles/ (Accessed July 2026).
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Chhabra D, et al. Microbial Pathogenesis 2023;178:106070.
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World Health Organisation. Available at: https://www.who.int/news-room/feature-stories/detail/vaccine-efficacy-effectiveness-and-protection (Accessed June 2026).