Strangles in Horses

During World War 1 Strangles was a feared disease as the army depended heavily on its mounted infantry. The close confinement of large numbers of horses sharing common watering and food facilities could result in this highly infectious bacterial disease running rampant through a population of horses.

Today the disease is less common but not less debilitating. The disease first appears as inappetance, high temperature and lethargy this later progresses to swelling around the throat region as the mandibular and pharyngeal lymph nodes enlarge. These swelling form abscesses which can rupture and discharge pus, this is often accompanied by a purulent nasal discharge. These discharges are the main source of contaminate to other horses. In unusual cases abscesses also form in a number of other locations including the lung, liver and surrounds of the eye. When this happens the disease is referred to as “Bastard Strangles”

Young horses in the age group of 1-5 years are usually more susceptible. A horse previously infected but showing no clinical signs may continue to act as a source of infection for 1-2 months even extending to 8 months. Once an outbreak has been suspected those horses displaying early clinical signs should be immediately isolated. Isolation should continue for a minimum of 4-5 weeks following disappearance of the signs. In addition personal hygiene is of the utmost importance as any object contaminated with discharge can become a source of continuing infection.

The disease is confirmed by a culture of the bacteria “Streptococcus equi” using a swab taken from an abscess or nasal discharge. To give some assurance that the animal is clear of the disease 3 repeat negative swabs taken at 7-10 day intervals are recommended. Treatment involves drainage of the abscess and a course of antibiotics extended for 5-7 days after the clinical signs have resolved. Early stoppage of the antibiotic treatment may result in a reoccurrence of the disease.

Vaccines are now available and assist in the reduction of the disease. The best vaccination program for increased immunity involves an initial dose followed by annual boosters. Vaccinated horses can still succumb to the disease but have milder symptoms.