Strangles is a dreaded disease for horse owners. It is caused by bacterial infection with Streptococcus equi subspecies equi (referred to as S. equi). The bacteria typically infect the upper airway and lymph nodes of the head and neck. Strangles has affected horses for centuries, is highly contagious, can recur on farms with previous outbreaks, and is one of the most commonly diagnosed contagious equine diseases worldwide. S. equi might survive in water sources (buckets and troughs) for more than a month, but primary sources of recurrent infections are asymptomatic carrier horses that shed the bacteria for months to years.

Call your veterinarian right away if you suspect an outbreak; he or she can accurately diagnose illness and recommend control practices. Some state veterinarian offices require practitioners to report cases. Do not transport horses on or off the farm, and take all resident horses’ temperatures twice daily (99-101.5°F is normal). Horses can transmit S. equi one to two days after developing a fever, so isolate at the first sign of fever to avoid spreading infection.

In an outbreak divide horses into three groups: 1) infected horses (with fever, nasal discharge, etc); 2) exposed horses ; and 3) unexposed horses. Nose-to-nose contact or bucket sharing should not occur between groups! Unexposed horses should be kept in a “clean” area, and they should have separate caretakers, equipment, water troughs, and pastures. People and shared equipment can transfer bacteria, so diligent hand washing and disinfection of supplies are necessary. If separate personnel aren’t possible, then always handle healthy horses first. Use protective clothing (boots, gowns or coveralls, and gloves) when managing infected horses.

Thoroughly clean and disinfect all water troughs daily during an outbreak, following disinfectant label instructions (and ensuring they’re labeled as active against S. equi). Disinfect all surfaces after removing manure/organic material, which inactivates some solutions. Compost infected horses’ manure and waste feed in an isolated spot–don’t put it on pastures. Rest sick horses’ pastures for at least four weeks