By: Katie Jones, CVT

The Streptococcus equi bacterial disease causes horse owners to cringe and barn owners to become nervous. “Strangles” is the term used to describe this condition seen in infected horses when the lymph nodes around the throat become large enough to suffocate the horse. It typically occurs in horses 1 to 5 years old.

Causes: Exposure via direct contact with an infected horse or contaminated objects.

Incubation period: 3-14 days

StranglesClinical Signs:

  • First sign of infection is a fever ranging between 103°F-106°F.
  • 24-48 hours after the fever spike: nasal discharge, depression, inspiratory respiratory noise, and difficulty swallowing.
  • The horse may keep their head down and neck stretched out.
  • The lymph nodes become swollen and painful due to the formation of abscesses.

Diagnosis: Confirmed by a bacterial culture collected with a nasal swab.

strangles1Treatment: Under a veterinarian’s direction.

  • Hot compressions to swollen lymph nodes to encourage drainage. If they don’t drain on their own, they may need to be lanced and flushed.
  • Suspected infected horses need to be isolated from others.
  • If the lymph nodes are swollen to the point the horse is struggling to eat, they should be fed a soft diet.
  • Penicillin is an effective drug for treatment. Occasionally, if Penicillin is started before enlarged lymph nodes are seen, the disease process could stop.


  • The abscesses can rupture and drain through the skin, into the throat and nasal passages, or into the guttural pouch. Each of these conditions has different treatment options and complications.
  • The future development of “Bastard Strangles”.
    • Caused by: The infection spreading into the blood stream; thus, traveling to all the lymph nodes of the organs (liver, kidney, intestines, heart, spleen, and brain).
    • Clinical signs: Weight loss, episodes of colic, and a general decline of health.
    • Requires intensive veterinary management to recover.

Prevention: Strict hygiene protocol (quarantine)

  • A barn with a positive case should have everything disinfected which COULD HAVE come into contact with the horse (stall walls, buckets, ect.).
  • Traffic in and out of infected facilities needs to be restricted.
  • Available Vaccine. The immunity from both the vaccine and natural exposure is short lived. This vaccine is recommended if the horse is at a boarding facility or travels to shows throughout the year.
  • Three negative nasal swabs should be obtained before allowing an infected horse to re-enter a herd.

Strangles 2

Long Term Effect: Most horses which become infected will shed the bacteria for approximately a month after recovery.