10/05/2026
STRANGLES: WHAT HORSE OWNERS SHOULD KNOW
An educational post from Dr. Elizabeth Cheyne and Dr. Amanda Craven of McKinlay & Peters Equine Hospital
Strangles is a highly contagious respiratory disease in horses. Knowing the signs, understanding how it spreads, and taking appropriate biosecurity precautions can help protect your horse and others in the equine community.
Here are some of the most important things horse owners should know:
1. What is Strangles?
a. Strangles is an upper respiratory disease of horses caused by a bacteria called Streptococcus equi. A fever will precede any other clinical signs by 24-48 hours. Horses can have a soft cough, mucopurulent nasal discharge, and enlarged and/or abscessed lymph nodes near the jaw. Less common signs are difficulty breathing giving this disease its name, guttural pouch empyema, and widespread abscessation or inflammation.
2. How does my horse get Strangles?
a. Transmission is most often from direct horse to horse contact. It can also be spread from contaminated equipment and handlers, and also through the air if the horse has enough nasal discharge.
3. How is Strangles diagnosed?
a. The typical first test is a nasal secretion PCR that looks for the DNA of the bacteria. If this sample is taken early enough, the PCR result may be negative, so repeat testing is recommended if the clinical signs are consistent with Strangles. A culture of nasal secretions can also be performed to rule out other bacteria.
4. How should my horse be treated for Strangles?
a. Treatment is supportive care only unless the horse is experiencing complications. Importantly, antibiotics are often not indicated because they prevent a full antibody response, leaving the horse susceptible to reinfection or to become a carrier of the disease.
5. How contagious is Strangles?
a. This is a very contagious disease and quarantine protocols should be taken seriously. Ideally, horses should be separated into clean, exposed, and sick groups, and should be cared for in that order. If space is limited, at the very least horses should be separated so that they can’t have nose to nose contact.
b. Twice daily temperature monitoring is recommended. It is important to not share any equipment between groups of horses and to thoroughly disinfect common surfaces. The most easily accessible disinfectant is bleach diluted 1:10. Rubber items can be cleaned with 70% isopropyl alcohol and clothes can be washed with 3% hydrogen peroxide or Lysol. A shower and clothes change is required if a person has to move from a sick or exposed horse back to an unexposed horse.
c. All movement of horses on or off of the property should be stopped until a minimum of 3 weeks has passed since the last affected horse has tested negative.
d. Sick or exposed horses should not be allowed into any common area or allowed contact with an unexposed horse.
6. When would I start seeing signs if I’m worried my horse was exposed?
a. Clinical signs including fever usually start 3-14 days after exposure. Once the horse develops a fever, the bacteria begins to be shed in nasal secretions 2-3 days later.
7. Should I vaccinate my horse?
a. The Strangles vaccine is a risk based vaccine that is typically given annually based on risk or requirements.
b. Vaccination in an outbreak is not recommended as it increases the risk of complications.
8. How do I know my horse is Strangles-free?
a. The only way to definitively know is to test the horse. Shedding of the bacteria can occur for 2-3 weeks following resolution of clinical signs. The best test to definitely rule out carrier status and confirm recovery is a negative PCR from a Gutteral pouch lavage after resolution of clinical signs.
9. What do I do if my horse is determined to be a carrier?
a. Continue treating them as if they are sick even if they are not showing any signs. Your Veterinarian will advise you on the best course of action.
10. How do I prevent my horse from being exposed?
a. Vaccination when there is not an outbreak helps protect your horse. If you board your horse, know what quarantine protocols they have ahead of time. Do not allow your horse to be in contact with horses that have enlarged lymph nodes, nasal discharge, or fever.
References
1. AAEP biosecurity guidelines: Disinfectant table. (2017).https://aaep.org/wp-content/uploads/2025/05/AAEP-Biosecurity-Guidelines-Disinfectant-Table.pdf
2. Strangles. (2020).https://aaep.org/wp-content/uploads/2024/03/Strangles_DZ_Guidelines_FINAL_2020.pdf
3. Streptococcus equi Infections in Horses: Guidelines for Treatment, Control, and Prevention of Strangles—Revised Consensus Statement. (2018). https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/jvim.15043
