27/01/2026
Strangles in Horses – What Every Owner Needs to Know
Strangles is a highly contagious bacterial disease of the upper respiratory tract and lymph nodes of the head, caused by Streptococcus equi. It affects horses, ponies and donkeys and is considered endemic, with outbreaks most commonly occurring during the cooler months. Outbreaks often follow the mixing of horse groups or the introduction of a new horse from an infected property.
The bacteria spread rapidly via nasal and oral secretions, coughing, contaminated feed and water, shared gear (halter, rugs, grooming equipment), transport vehicles and people who are not practicing correct biosecurity. Birds may also transmit the bacteria from feed bin to feed bin. The incubation period is typically 3–8 days, though it can be up to three weeks.
Common clinical signs include:
• Sudden high fever (39.5–40.5°C)
• Loss of appetite and depression
• Painful swelling of lymph nodes under the jaw and throatlatch
• Thick yellow nasal discharge
• Coughing and difficulty swallowing
In most cases, once abscesses mature and drain, horses recover well. However, affected horses can remain infectious for at least four weeks after signs resolve. Some horses become chronic carriers, harbouring the bacteria in the guttural pouch and shedding it intermittently for months, posing an ongoing risk to others.
If strangles is suspected, immediate veterinary involvement and strict isolation are essential. Diagnosis is confirmed via veterinary nasal swabs taken before antibiotics are started.
A serious complication is bastard strangles, where the bacteria spread beyond the throat and form abscesses in internal organs such as the lungs, liver, spleen or brain. This causes signs like weight loss, colic, fever or neurological symptoms and can be fatal, making early diagnosis and veterinary care critical.
Treatment is largely supportive, focusing on good Nutrition, pain relief and biosecurity.
Prevention is critical. Quarantine new arrivals, practice strict hygiene, avoid sharing equipment, and consider vaccination, particularly for horses that travel, agist or compete. While vaccination does not guarantee complete protection, it can significantly reduce disease severity and limit spread during outbreaks.
Early recognition and responsible management protect your horse—and the wider equine community.
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