PINNACLE® I.N. Intranasal Streptococcus Equi Vaccine To help protect horses against strangles, look to PINNACLE® I.N. –the only two-dose, modified-live bacterial vaccine developed to help prevent strangles caused by Streptococcus equi (S. equi). Strangles is a highly contagious upper respiratory infection most common in young horses. Strangles symptoms can include fever, difficulty swallowing, abnormal breathing, nasal discharge, swelling and/or abscesses of the lymph nodes.1 The disease can spread quickly and is easily transmitted through direct animal-to-animal contact or by objects — buckets, bridles or human hands — that have come in contact with infected horses. Your horse may be at risk for strangles if he travels to events or shows or is exposed to unfamiliar horses, such as within a boarding barn.