Section 1 | Respiratory Diseases in Horses: Streptococcus equi

Ontario Equine
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Prevention of Strangles

Prevention is the best approach when it comes to animal health. This is why it’s so important to focus on biosecurity, or infection control. The key is to prevent your horses from being exposed to these pathogens in the first place.


Some key practices include:

  • Quarantine and screen all new arrivals to your facilities
  • Clean and disinfect equipment and stalls
    • Rid the surface of organic matter, rinse with water, apply a disinfectant according to manufacturer’s directions, and allow the area/equipment to dry. This will be effective in killing Streptococcus equi
    • Streptococcus equi is relatively susceptible to disinfection using bleach, quaternary ammonium compounds, and accelerated hydrogen peroxides
  • Use proper personal hygiene practices. Caretakers should always wear clean clothing, change clothing between barns, work from uninfected to infected or quarantined horses, and most importantly wear and change gloves or wash hands between animals
  • Isolate horses suspected to be infected with Streptococcus equi as soon as possible


Quarantine and Screening of Arriving Horses

Ensuring that all horses entering the barn are free of Strangles is critical. New arrivals and horses returning to the barn should be quarantined for at least 3 weeks, observed daily for illness, and body temperatures should be evaluated twice daily to identify a fever. Be sure to get a thorough history of any animals entering your barn to ensure that they have not been ill recently, as these animals could be sources of infection.


The quarantine area should:

  • Be separated from the rest of the horses on the premise
  • Have dedicated and clearly marked equipment
  • Be attended by staff who do not deal with other horses or be seen by staff after they have dealt with the other horses


Your veterinarian can help you screen new horses to identify those silent carriers mentioned above (e.g. guttural pouch infections). They can take a sample and send it to a commercial laboratory to screen for the presence of Streptococcus equi. Work with your veterinarian to develop an entry protocol for new horses. Will you require that each new horse be vaccinated for Strangles? Or will you require negative tests prior to entry? What about a health certificate from their present veterinarian?

What About Vaccination?

As horses are one of the most widely traveled animals, vaccination can play a role in protecting horses against Streptococcus equi while at equine events. Horses who have previously had Strangles should not be vaccinated as they may already have good immunity against it. If you do not know your horse’s full medical history, your veterinarian may suggest a blood test to determine its immunity level prior to vaccination. Work with your veterinarian to develop a vaccine strategy for your horse/s to manage the risk of previous and future exposure.

For more information on vaccination, check out our page within the Antimicrobial Stewardship FAAST Review, Vaccination as a Key Animal Health Tool.