What is Strangles?

Strangles is a respiratory disease of horses caused by the bacterium Streptococcus equi. It is one of the most common contagious diseases affecting horses worldwide.1

In this section learn:

  • The signs of Strangles
  • The risk of Strangles
  • About vaccination with Equivac® S
  • About myths associated with the disease

Strangles is highly debilitating.2,3 Horses usually show signs of strangles within 3 to 8 days of becoming infected.2 The common signs of strangles include:1–3

  • A nasal discharge (a greenish, yellow, or white “snotty” discharge)
  • Fever (39–40°C)
  • Difficulty swallowing
  • Loss of appetite
  • Depression
  • Cough
  • Swellings that are a result of abscesses of the lymph nodes in the head and neck region due to an accumulation of pus
  • Laboured breathing due to enlarged lymph nodes – hence, the name “strangles”.

These distressing clinical signs can persist for days, weeks or months. Most horses recover, but they may need to be isolated for 6 to 8 weeks.2

Strangles is a highly contagious disease and is rapidly spread from horse to horse.1, 3 Strangles is spread via the pus or discharge from infected horses’ noses, draining lymph nodes, or by coughing.2

Direct contamination

  • Direct contact among horses2
  • Nose-to-nose contact with neighbouring horses or contamination via flies2

Once infected, horses can shed the bacteria for weeks or months (and occasionally years), even after recovery, potentially infecting other horses.2

Indirect contamination

  1. Contaminated grooming equipment, shared tack or rugs2
  2. Contamination via human contact or contaminated clothing3
  3. Sharing of feed or water contaminated by nasal discharge or pus from an infected horse2

The strangles bacterium can survive in the environment for weeks or possibly months, causing an ongoing risk.3

Strangles is a notifiable disease in some States – if your horse is affected, check with your vet to see if you need to report strangles to your local authorities.

Vaccination is recommended to help avoid this serious condition.1,3

You can vaccinate your horse against strangles with Equivac S or Equivac 2 in 1, available from your vet.

Your foal can get this vaccination from 3 months of age. Initially, it is given as 3 doses no less than 2 weeks apart, followed by annual boosters to maintain immunity. Increased protection against strangles may be obtained by giving booster doses more frequently, for example every 6 months.

Myth: Strangles is not fatal

Strangles infection can spread to lymph nodes in areas other than the head or neck (e.g. chest or abdomen). This is known as “bastard” strangles. This type of infection can be extremely difficult to cure and is frequently fatal. Strangles can also cause damage to the blood vessels and lead to swelling of the head or legs, circulatory failure and death.2,3

Myth: Strangles affects only young horses

While strangles commonly affects foals and younger horses, horses of any age can be infected.2,3

Myth: Only horses with signs of strangles can infect others

Some horses can outwardly show no signs of strangles, yet they can still carry the infection and spread it to other horses.1 This is why it’s important to minimise the risk of infection at all times.


  1. Strategy to Eradicate and Prevent Strangles (STEPS). The British Horse Society, Scotland, 2011.
  2. Queensland Horse Council Inc. Strangles Fact Sheet, May 2010.
  3. Biosecurity NSW. PrimeFact 648, Third Edition, May 2012. NSW Department of Industry and Investment.

Don't Wait to Vaccinate



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