Exacerbation of Streptococcus Equi (Strangles) by Overly Nutritious Diets in Horses: A Model for Infectious Bacterial Diseases of Horses and Other Livestock

Strangles is a highly pathogenic and contagious infection of horses and other equids caused by Streptococcus equi. Reports in the literature summarize the severe complications of strangles, but provide little information on the factors enhancing the pathogenicity and complications that result in high mortalities. However, there are reports suggesting exceptionally nutritious diets will exacerbate strangles infections and promote complications, including bacteremia and metastases to lymph nodes throughout the body and sequalae like purpura hemorrhagic and myositis. Dietary ingredients may enhance S. equi capsular polysaccharide (CPS) which protects bacteria from the immune system and phagocytosis. Low-virulent bacteria may become highly virulent pathogenic bacteria. Overly nutritious diets enhance the pathogenicity of S. equi and efficiency of bacterins, vaccines and antibiotics intended for controlling and treating strangles in horses. The effect of diet on the pathogenesis of S. equi in horses may be an ideal model for other bacterial diseases of horses as well as bacterial diseases like Pasturella multocida respiratory infections in cattle and other livestock