Purpura haemorrhagica is an immune-related complication where blood vessels become inflamed, causing severe swelling, pain, and sometimes bleeding under the skin.1,9 Recovery can take a long time, and severe swelling can leave permanent damage to the limbs.1,9 It can also be fatal.1,9
If not identified and managed, strangles can spread rapidly through a yard.1,3,4 The consequences of this transmission can be severe.1,2
Select one of the facts below to find out more about how strangles can be a serious threat to your stables.
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Strangles represents approximately a quarter of all equine infectious respiratory disease cases.5 An S. equi infection can lead to complications, such as respiratory distress, guttural pouch empyema and purpura haemorrhagica.1,2,4 The risk of mortality from a strangles infection is up to one in ten horses.1,2
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A strangles outbreak can have significant financial consequences for a yard, from increased veterinary and staffing costs to investment in additional biosecurity measures such as fencing, PPE and disinfectants. It can also disrupt day-to-day operations, restrict attendance at events and lead to lost income if the yard is forced to close.6
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The financial dangers of strangles can soon take a toll.7 One study from 2016 reported that the average monthly cost incurred during an outbreak was £7,814 per month.7 This included buying additional stocks and supplies, extra staff time, and the need for veterinary diagnostics and transportation.7
A strangles outbreak can impact your yard in many ways2,7,8
Strangles mythbuster
Strangles is just
like a bad cold
This is a common misconception. While many horses
recover with supportive care, strangles can cause real
suffering (painful swollen glands, breathing difficulty,
high fever) and carries a high risk of serious
complications and even death, particularly if it’s
not caught and managed early.1,2
Rapid implementation of strict biosecurity measures
and vaccination can greatly reduce the impact
of a strangles outbreak on your yard2,3,6
FAQs – Your questions answered
What is purpura haemorrhagica and how serious is it? add
Can healthy horses spread strangles? add
If a horse appears outwardly healthy, it may not be recognized as having the potential to spread strangles, but it is important to remember:1,3
- A horse may be infected, but not yet show any clinical signs
- A horse may have atypical strangles. This horse can have very mild clinical signs of strangles with no obvious abscesses
- Horses not yet fully recovered from the disease can still shed the bacteria
- In around 10% of horses, strangles persists in the guttural pouch after recovery from the acute disease. These ‘carriers’ look healthy but can intermittently shed the bacteria for months or years with potential to infect other horses
References add
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Boyle et al. J Vet Intern Med. 2018;32:633–647.
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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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Pringle J, et al. J Vet Intern Med. 2020;34(1):294–299.
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National Equine Health Survey (NEHS) 2018. Available at: https://www.bluecross.org.uk/sites/default/files/d8/2022-01/NEHS-results-2018.pdf (Accessed July 2026).
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Robinson C, et al. Vaccine. 2020;38(31):4861–4868.
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Redwings. Redwings Strangles Survey Results: Main report 2017. https://www.redwings.org.uk/sites/default/files/2023-09/Strangles%20survey%20results%20main%20report%202017%20FINAL%20small_0_0.pdf (Accessed July 2026).
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Gröndahl G, et al. Equine Vet J. 2026;58:476–485.
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MSD. Immune-Mediated Myopathies in Horses. Available at: https://www.msdvetmanual.com/musculoskeletal-system/myopathies-in-horses/immune-mediated-myopathies-in-horses (Accessed July 2026).