The assistant state veterinarian has reported that a case of strangles has been confirmed in one horse in King County, Washington, with eight other horses suspected to be positive. The private facility where the infected horses are located has implemented a self-imposed quarantine.
EDCC Health Watch is a marketing program of the Equine Network that utilizes information from the Equine Disease Communication Center (EDCC) to create and distribute verified equine disease reports. The EDCC is an independent nonprofit organization that relies on industry donations to provide accessible infectious disease information.
About Strangles
Strangles is an infection in horses caused by Streptococcus equi subspecies equi and is transmitted through direct contact with other equids or contaminated surfaces. Horses that are asymptomatic can carry and spread the bacteria, and even recovered horses can remain contagious for up to six weeks, potentially leading to long-term outbreaks.
Clinical signs of strangles in infected horses may include:
- Fever
- Swollen and/or abscessed lymph nodes
- Nasal discharge
- Coughing or wheezing
- Muscle swelling
- Difficulty swallowing
Veterinarians typically diagnose strangles in horses using polymerase chain reaction (PCR) testing with samples from nasal swabs, washes, or abscesses, and treatment is based on clinical signs, with antibiotics being used in severe cases. Excessive use of antibiotics can hinder the development of immunity in infected horses. Most horses recover fully within three to four weeks.
Although a vaccine for strangles is available, its effectiveness can vary. Implementing biosecurity measures such as quarantining new horses and maintaining high levels of hygiene and surface disinfection can help reduce the risk of outbreaks and contain them if they occur.

