Katie Hennessy


Strangles (Streptococcus equi subspecies equi) is always a concerning buzz word around the horse community. The bacteria causes an upper respiratory infection which results in swelling of the lymph nodes in the upper neck and head region. The strangles bacteria is extremely resilient and contagious. It can survive on buckets, water troughs, equipment, and in the environment for up to a month. Some horses can be infected but not show signs of disease while shedding bacteria for months to years from their guttural pouches. Most new cases occur after traveling with your horses or when a new horse has arrived on the property.


The signs to watch out for include lethargy, decreased appetite, fever, swelling on the neck or head, and nasal discharge.  Some horses may have difficulty swallowing and the lymph nodes beneath and behind the jaw bone swell which may later burst out as mature abscesses. Your veterinarian will diagnose strangles by taking a swab of the discharge for culture or PCR testing. It is critical to positively diagnose strangles as quickly as possible because it is a reportable disease and proper precautions must be taken to prevent spreading the disease.


Despite strangles being a bacterial infection, antibiotics are rarely initiated because it delays maturation of the abscesses and can prolong the disease. A large majority of infected horses recover but a complication of the disease is when there is abscessation of other lymph nodes of the body. This is known as “bastard” strangles. Warm compresses to help facilitate maturation of the abscesses, flushing ruptured abscesses with dilute povidone-iodine and NSAIDS are often the only treatment needed.


How to prevent the spread of strangles:

  • • Isolate any horses showing signs
  • • Keep infected horse’s equipment (troughs, buckets, brushes etc.) separated
  • • Good biosecurity – use disinfectant on boots, wash hands etc. between handling    horses
  • • Take healthy horse’s temperature twice daily to catch early infection
  • • Muck out/feed/groom infected horses after finishing with healthy horses

A strangles vaccine is available but vaccination does not prevent the disease. Vaccines reduce the severity of clinical signs in an infected horse because the horse has antibodies to fight the disease. Vaccination is something you should discuss with your veterinarian to see if it’s suitable for your horse.

This column is sponsored by Polk Equine, and the opinions expressed herein may not reflect those of CFAN or of its advertisers.

BIO: Dr. Katie Hennessy graduated from the University of Illinois College of Veterinary Medicine in 2008 with a degree in large animal health and equine medicine. She completed an advanced internship at The Equine Medical Center of Ocala and is currently the owner and practicing veterinarian at Polk Equine. Her expertise ranges from small and exotic creatures to large animals, specializing in equine medicine.

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