What is Strangles?

Strangles is a plague of the horse world – it can spread like wildfire among groups of horses.

It’s called Strangles because, in severe cases, swelling of the lymph nodes in the head and neck restrict the airway, effectively strangling the horse.

Strangles is one of the most commonly diagnosed infectious diseases of horses worldwide with more than 600 outbreaks in the UK each year. It causes immense welfare problems for horses and significant economic costs to their owners.


S.equi, the bacterium which causes Strangles, on an agar plate in the AHT's laboratories

Researching Strangles

Some horses which recover from Strangles remain persistently infected with Streptococcus equi (S.equi) and can pass the infection to other horses, even if they’re not showing any signs. To prevent future outbreaks we need to identify and treat animals carrying the infection before they can pass it on.

Our scientists have pulled apart the DNA of S. equi to learn more about how it causes disease. From this we developed effective tests for identifying carriers. These tests are preventing thousands of cases of Strangles around the world every year.

Now, we’re using our knowledge of S. equi to develop Strangles vaccines which will help protect horses whilst they attend equine events or move around the world.

Strangles can be beaten. Our research is making a difference. Your support can help us develop safe, effective vaccines so we can finally get to grips with this terrible disease.

Dr Andrew Waller
Dr Andrew Waller, Head of Bacteriology Research

600 outbreaks of Strangles are reported each year in the UK alone

100,000 uses of our diagnostic blood test since its launch

Support our Strangles research

Help us to make a difference

Donate now

Research lead

Dr Andrew Waller

Dr Andrew Waller

Head of Bacteriology Research

Andrew’s research is dedicated to improving the health of animals by reducing the incidence of streptococcal disease, such as Strangles.

Read Dr Andrew Waller's bio