One of the most alarming infectious diseases in the equine industry is strangles, which is noted for the characteristic large swelling of lymph nodes under the jaw or in the throat area. Sometimes the node enlargement progresses to the point of interfering with airway or swallowing functions creating a concern that the patient might strangle.

Strangles, also known as equine distemper, is caused by a bacterial infection of the highly infectious Streptococcus equi. Although the disease is potentially fatal, the mortality rate is generally less than 10%. The morbidity rate, however, is quite high due to the infectious nature of the germ and its ability to survive once infected horses contaminate the environment. The disease has an incubation period ranging from a few days to two weeks. Therefore, minimum isolation time of two weeks is recommended with horses that have been exposed, or horses having an unknown history for biosecurity purposes.

"We see it so commonly in young horses when the germ is found in endemic areas; the younger animals often lack adequate immune protection" said Glennon Mays, DVM, clinical assistant professor at the Texas A&M University College of Veterinary Medicine and Biomedical Science. "That means that once a location is contaminated with strangles, we often see it reappear in the horse population because the bacterium is located in that environment. When horses are born or brought to that location, if they don’t have protective immunity, they become infected."

The S. equi germ can survive in contaminated soil, water troughs, feed buckets, and tack. The germ can even be transferred