On October 25, one premise in Miami-Dade County, Florida was placed under quarantine for strangles, according to a recent Equine Disease Communication Center (EDCC) alert. Clinical signs began Oct 18. No animals have left the facility since clinical signs began. This is the fourth case in Miami-Dade County and the 21st case for Florida in 2016.
Strangles poses no risk to humans, but is highly contagious and common among horses. Strangles is caused by infection with Streptococcus equi subspecies equi.
Symptoms include fever, diminished appetite, nasal discharge (that begins clear and turns purulent) and enlarged submandibular lymph nodes that can become abscessed. It is in the obstructed breathing caused by enlarged lymph nodes and in rare cases death by suffocation that the disease received its name. In most cases, infection with S. equi self-resolves, but this disease has a death rate of about ten percent, usually from complications involving spread beyond the head and neck, including pneumonia.
Transmission occurs by direct contact between animals and via fomites or water sources. Treatment can include chemotherapy with antibiotics if initiated in the very early stage of the disease or as post-exposure prophylaxis; otherwise, initiation of antibiotic treatment is not recommended due to evidence that it can prolong infection or inhibit formation of post-infection immunity. As about twenty percent of cases become asymptomatic nasal carriers, vaccination is the considered the best method of control.