Is among the oldest most important diseases of equine. The name comes from the horse making strangled breathing sounds resulting from enlarged lymph nodes of the neck and head. Strangles can affect horses, donkeys and mules of all ages, but usually those younger than two years of age.

Typical symptoms include:
  • High temperature, above 38.5°C, is often the first sign. This provides an opportunity to immediately isolate the horse and help prevent the spread of the disease.
  • Lethargy/dull and depressed.
  • Loss of appetite and/or not drinking, difficulty swallowing.
  • A lowered head and neck.
  • A cough.
  • Thick and discoloured nasal discharge.
  • Swelling of the glands under the jaw (lymph nodes), in the space between the head and neck, or on the head or neck which may lead to abscesses. These can burst with highly infectious, thick, creamy-yellow pus.
  • The abscesses in the lymph nodes usually burst into the horse’s guttural pouches (air pockets at the back of a horse’s throat) which then drain out through the nostrils.

It normally takes 3-14 days after the horse has been in contact with the strangles bacteria for signs to develop (incubation period). However, there have been times when it has taken up to 28 days.

If you suspect strangles
  • Isolate the horse(s) affected.
  • Call your vet.
  • Contact owner(s) – including those of horses who have been in contact with the affected horse.
  • Monitor other horses on your yard for signs of infection.
  • Spread the word, not the disease – tell people such as your farrier and any nearby equine property.

Strangles is caused by a bacteria called Streptococcus equi that can be easily spread directly through horse-to-horse contact and indirectly, for example through contaminated equipment, handler clothing and boots. It’s so-called because the airway can become restricted by swollen lymph nodes.

While strangles is not spread through the air (airborne), the bacteria can spread when a horse coughs or snorts.

Atypical strangles

Not all horses will show the same signs, or even any at all. This is called ‘atypical strangles’. Some horses may only show signs such as:

  • A mild fever
  • Other forms of nasal discharge
  • A slight loss of appetite

Atypical strangles may go unnoticed but infection can still spread. If you notice your horse showing mild signs, it’s always sensible to isolate them as a precaution and contact your vet for advice.


Your vet will advise on the best treatment for strangles but this will mainly involve nursing the horse with supportive care. Where multiple vet practices are involved (for instance, on a DIY livery yard) vets will often work together to put a plan in place for the whole yard and designate a lead vet to ensure clear communication.

Most horses recover from strangles in 3-4 weeks. It’s extremely important not to remove horses from isolation just because their symptoms have gone. Strangles bacteria can spread for around six weeks after signs of infection have gone, sometimes longer.

Testing is the only way to ensure your horse is no longer infected and is safe to remove from isolation. Your vet will advise on when to test and what type of test to do.


Infection can remain in around 10% of strangles cases. This leads to a horse becoming known as a ‘carrier’; they’ve fully recovered from strangles and aren’t showing signs of infection but are still infected and able to spread the bacteria to others. You will not be able to determine whether your horse is a carrier by visibly looking yourself.

Treating carriers

Usually, the pus from abscesses dries and forms balls called chondroids, these will be identified by your vet through a guttural pouch endoscopy. Chondroids are removed from the guttural pouch and antibiotics may be required to kill any remaining bacteria. Horses are re-examined after two weeks to check if they are then free from infection.


Speak with your vet to arrange testing for all new arrivals. This could be a guttural pouch endoscopy or a blood test depending on what your vet advises.

There is a strangles vaccine currently available for use in the UK.  The vaccine should be seen as an additional measure and not a replacement for good hygiene and disease prevention measures. Your vet will be able to advise whether the vaccine would be suitable for your horse and individual situation.