Strangles is one of the most recognized bacterial diseases affecting our horses. Caused by Streptococcus equi (S. equi), strangles is a highly feared and contagious disease that no horse owner wants associated with his/her facility. Horses in high traffic areas (e.g., racetracks, show grounds, transient farms, shipping) are at greatest risk. Usually young horses are more susceptible than older horses. The most common signs of strangles are sudden onset of fever, nasal discharge, dull listless behavior and abscesses located in the neck and throat area. Other symptoms may include difficulty swallowing and breathing, soft moist cough, and an elevated white blood cell count.


Contrary to previous belief, the S. equi organism has a short lifespan. It lives in soil for 3 days, on fence posts for 7 days and for 30 days in water (e.g., water buckets, hoses and nozzles, troughs, puddles). Strangles remains one of the most highly contagious diseases that we deal with. Spread of the disease can occur directly from horse to horse (one clinically ill or an asymptomatic carrier) or indirectly through contact with infectious materials (fences, water containers, brushes, bedding, handler contact, etc.). Recent research indicates that infectious outbreaks may occur through an asymptomatic carrier; an adult horse that has retained the bacteria in the guttural pouches (throat). [Note: A screening test is available to identify asymptomatic carriers. For more information ask your veterinarian.] For these reasons, careful management and control measures must be taken to minimize the spread of this disease.

  • Use dedicated equipment, tools, buckets, bedding, and if possible, separate personnel for each group to prevent cross contamination.
  • Quarantine all incoming horses for 3 weeks before.
  • Test all resident and incoming horses for asymptomatic carrier status. Keep resident and incoming horses separated.
  • Monitor temperature (twice daily) of all horses that have been exposed during an outbreak in order to separate clinically ill horses as early as possible. Example groups: 1) clinically ill horses, 2) exposed horses and 3) unexposed, healthy horses.
  • Properly dispose of waste and bedding in an area that will ensure other horses do not come in contact with it.
  • Treat and monitor clinically ill and infectious horses until they reach a noninfectious state.


Hagyard Equine Medical Institute has one of the highest equine caseloads in the world. Because we run a state-of-the-art hospital, we are dedicated to providing the best veterinary care possible to our patients. As part of our veterinary services, we run an infection control program to control and prevent infections in our patients during hospitalization. The main goal of this program is to develop an early warning system for detection of disease causing organisms and help prevent the potential spread of disease. This system includes monitoring temperatures several times daily and diligent isolation of horses having or suspected of having infectious diseases.