What is the aetiology of strangles?

Strangles is caused by the bacterium Streptococcus equi, which primarily affects horses. The bacteria are highly contagious and spread through direct contact with infected animals or contaminated surfaces, such as feed and water troughs. Once inside the horse, S. equi invades the lymphatic system, leading to inflammation and the formation of abscesses in the lymph nodes, particularly in the throat region. Environmental factors, such as stress and crowding, can increase susceptibility to infection.