A 25-year-old Thoroughbred mare at a boarding facility in Sonoma County, California, was diagnosed with strangles on Aug. 13 after presenting with a cough on Aug. 7. She is currently isolated for treatment. Another horse is suspected to be positive, and 30 horses have been exposed to the infection.
EDCC Health Watch, a program by Equine Network, shares verified equine disease reports from the Equine Disease Communication Center (EDCC), an independent nonprofit organization supported by industry donations. The EDCC provides open access to infectious disease information.
About Strangles
Strangles is an infection in horses caused by Streptococcus equi subspecies equi and is transmitted through direct contact or contaminated surfaces. Infected horses can spread the bacteria even without showing symptoms, and recovered horses can remain contagious for up to six weeks, leading to potential long-term outbreaks.
Clinical signs of strangles in horses include fever, swollen or abscessed lymph nodes, nasal discharge, coughing, muscle swelling, and difficulty swallowing. Veterinarians diagnose the infection using polymerase chain reaction (PCR) testing and treat cases based on clinical signs, with antibiotics prescribed for severe cases. Overusing antibiotics can hinder the horse’s immunity development. Most horses recover fully within three to four weeks.
Although a vaccine is available, it may not always be effective. Implementing biosecurity measures such as quarantining new horses and maintaining high hygiene standards can help reduce the risk of outbreaks or contain them if they occur.