How to reduce the risk, recognize the symptoms, and take steps to manage an outbreak. Strangles is a highly contagious infection caused by the bacterium, Streptococcus equi (S. equi). It is not an airborne virus. Rather, the bacteria spreads through contact, which could be direct nose-to-nose between horses, or via contaminated surfaces or equipment such as shared halters, lead shanks, cross-ties, feed tubs, stall walls, fencing, clothing, hands, the hair coat from other barn pets, grooming tools, water buckets, and communal troughs.
