Horses in two counties in Michigan have been confirmed positive for strangles.
In Lapeer County, two horses are positive, and three additional cases are suspected. The first positive case is a 6-year-old Quarter Horse that developed clinical signs on April 15, including inappetence and enlarged lymph nodes. Strangles was confirmed on May 11. The second horse is a Quarter Horse gelding that developed clinical signs on April 21, including nasal discharge. Strangles was confirmed on May 11.
In Ingham County, a 10-year-old Appaloosa gelding developed clinical signs on April 10, including difficulties swallowing and nasal discharge. Strangles was confirmed on April 26. The horse is recovering.
EDCC Health Watch is an Equine Network marketing program that utilizes information from the Equine Disease Communication Center (EDCC) to create and disseminate verified equine disease reports. The EDCC is an independent nonprofit organization that is supported by industry donations in order to provide open access to infectious disease information.
Strangles in horses is an infection caused by Streptococcus equi subspecies equi and spread through direct contact with other equids or contaminated surfaces. Horses that aren’t showing clinical signs can harbor and spread the bacteria, and recovered horses remain contagious for at least six weeks, with the potential to cause outbreaks long-term.
Infected horses can exhibit a variety of clinical signs:
- Swollen and/or abscessed lymph nodes
- Nasal discharge
- Coughing or wheezing
- Muscle swelling
- Difficulty swallowing
Veterinarians diagnose horses using polymerase chain reaction (PCR) testing with either a nasal swab, wash, or an abscess sample, and they treat most cases based on clinical signs, implementing antibiotics for severe cases. Overuse of antibiotics can prevent an infected horse from developing immunity. Most horses make a full recovery in three to four weeks.
A vaccine is available but not always effective. Biosecurity measures of quarantining new horses at a facility and maintaining high standards of hygiene and disinfecting surfaces can help lower the risk of outbreak or contain one when it occurs.