Horse Strangles: Managing a Highly Contagious Respiratory Disease

Strangles is one of the most common infectious diseases of horses globally, causing painful abscesses and serious complications. Good biosecurity and vaccination reduce its welfare impact.

Key Facts

Strangles is caused by Streptococcus equi subsp. equi, a highly contagious bacterium transmitted through direct contact and contaminated environments.
It causes fever, nasal discharge, and painful swelling of lymph nodes around the throat (submandibular lymph nodes), which eventually abscess and rupture.
The name "strangles" reflects the risk of throat swelling suffocating affected horses — this is rare but life-threatening.
Complications include bastard strangles (abscess formation in internal organs), purpura hemorrhagica (an immune-mediated vasculitis), and guttural pouch empyema.
Horses can become asymptomatic carriers — persistent guttural pouch infection is a source of ongoing shedding.
Vaccination is available and reduces disease severity; it is recommended for horses in high-risk environments.
Affected horses require isolation for at least 4-6 weeks from the appearance of last clinical signs.

Welfare Considerations

Strangles causes significant suffering. The swollen, abscessing lymph nodes are painful — affected horses show difficulty swallowing, depression, and obvious discomfort. The abscess formation and rupture process can take weeks, during which horses experience chronic pain. Complications like bastard strangles cause internal abscesses that are extremely difficult to treat and carry a poor prognosis. Purpura hemorrhagica is a serious immune reaction causing painful limb swelling and skin sloughing. The welfare management of a strangles outbreak requires appropriate isolation, pain management with NSAIDs, monitoring for complications, and skilled decision-making about when (or whether) to lance abscesses. Long-term carrier horses pose an ongoing welfare responsibility: they require guttural pouch treatment to resolve infection and end shedding.

What You Can Do

Implement immediate isolation if strangles is suspected — rapid containment prevents spread through the yard.
Call your vet immediately for any horse with fever plus nasal discharge and throat swelling.
Provide NSAIDs for pain relief throughout the course of illness — strangles is painful.
Test all in-contact horses with guttural pouch lavage or nasopharyngeal swabs before ending isolation.
Vaccinate horses in high-risk environments (competition yards, livery stables) against strangles.
Implement biosecurity protocols for all new horse arrivals — strangles spreads readily between horses through shared equipment and direct contact.