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Strangles remains a serious and highly contagious disease of horses. Outbreaks frequently occur following the unprepared introduction of new horses into a herd.

The causal organism is Streptococcus equi equi and it affects the upper respiratory system and lymph nodes of the head and throat. It is spread in two ways – by direct contact with infected horses or indirectly, through contaminated horse gear, bedding, feed bins, stables and humans inadvertently carrying the bacterium. Strangles more commonly affects younger horses, but all ages are susceptible in an outbreak.

Clinical signs

Symptoms of this potentially fatal disease include fever, depression, loss of appetite, yellow nasal discharge and swelling of the lymph nodes around the head and neck. These can abscess and burst.

Infected animals can become extremely ill and depressed, developing a high temperature within 3 to 8 days of exposure to the infection. Swallowing food or water becomes very painful, the lymph nodes around the head and throat swell (and may eventually burst), a yellow nasal discharge develops and often the horse has a cough. Clinical signs can last for weeks, especially if abscesses develop and rupture.












Strangles is painful and debilitating and immediate veterinary intervention is recommended. Treatment includes antibacterials, opening and draining any existing abscesses, providing pain relief and general supportive care, including minimising any sources of stress.

Isolate infected horses for at least 8 weeks, and maintain strict hygiene – this is a highly contagious disease. Treat the horse’s environment as well – decontaminate stables, bedding, food bins and take great care with your own hygiene, especially when moving from infected to uninfected horses in your care.


In most cases, recovery is uneventful but it’s essential to remember – horses can remain infectious for at least four weeks after apparent recovery, and in some individuals the carrier status persists for many months.

The organism is tough and can also persist in the environment for weeks and months in moist and temperate conditions.


The advice below is relevant both to protecting the individual horse and to minimising the risk of outbreaks.

  • Quarantine all new introductions and check daily. Horses incubate strangles for 3 to 8

days before appearing sick, and can remain infectious for months after recovery.

  • Ring us immediately if your horse develops a fever (over 38.3°C), runny nose or swellings under the jaw.
  • Institute a vaccination program in all unvaccinated horses. Horses require three initial doses two weeks apart, followed by annual boosters – click here to refer to our equine vaccination sheet for more information.
  • Maintain strict hygiene protocol. Strangles passes easily and rapidly from horse to horse, and via people moving between horses, sharing gear, feed and water containers.
  • If you are aware of a strangles outbreak, consider cancelling planned travel for your horse to competitions and meets. The safest place for your horse is on your property.