Strangles is a highly contagious infection of the upper respiratory tract and lymph nodes. Affected horses display clinical signs such as greenish, yellow, or white “snotty” discharge, fever, loss of appetite/anorexia, depression, cough, and swellings that are a result of abscessation of the lymph nodes. More serious complications include the spread of abscesses to various sites (bastard strangles) and purpura hemorrhagica (immune-mediated inflammation).

The strangles vaccine currently available is a modified live strain (in which live microorganisms have been modified so they are not pathogenic but will still cause the horse’s immune system to mount an immune response) that is quickly recognized and eliminated by the immune system. However, vaccinated horses sometimes present with respiratory symptoms or abscesses. Test results can help owners and veterinarians determine whether the infection is vaccine-induced, or if a horse needs to be quarantined due to infection by the wild type of strangles.

The assay to differentiate between the two strains costs $100, and results are ready in one week