Strangles Overview

Strangles is a highly contagious bacterial infection caused by the bacterium Streptococcus Equi subspecies equi (S.equi var. Equi).
Typically young horses are affected (commonly weanlings and yearlings), but horses of any age can be infected. Vaccination against Strangles is recommended on premises where strangles is a persistent endemic problem or for horses that are expected to be at high risk of exposure.

The organism is transmitted by direct contact with infected horses or sub-clinical shedders. Transmission can also occur indirectly by contact with people, water troughs, hoses, feed buckets, pastures, grooming equipment and even insects contaminated with nasal discharge from infected horses. S. equi has demonstrated environmental survivability, particularly in water sources and when protected from exposure to direct sunlight and disinfectants.

Infection by S. Equi induces a profound inflammatory response. Clinical signs may include:

  • Fever (102° to 106° F)
  • Difficulty swallowing or anorexia
  • Harsh, high-pitched breathing sound
  • Swollen lymph nodes (+/- abscess)
  • Abundant nasal discharge with mucous and pus

More information on Strangles (Streptococcus Equi)

Printable information on Facts about Strangles & Biosecurity to Prevent Strangles from the Indiana Board of Animal Health


AAEP Core Vaccinations: