An unvaccinated donkey at a private facility tested positive in Volusia County, Florida, on May 19. He presented asymptomatically and has been isolated.
Additionally, on May 20 a 4-year-old Warmblood broodmare in Palm Beach County, Florida, tested positive after showing signs of mucopurulent nasal discharge, a 104.3-degree fever, and lymphadenopathy of the retropharyngeal lymph nodes (swelling or abscessation of the lymph nodes under the jaw) starting May 19.
A mare at a Palm Beach County, Florida, training facility tested positive on May 23 after presenting with a fever and enlarged submandibular lymph nodes on May 20. The horse has been quarantined, and six horses were also exposed.
All three Florida cases were reported by the Florida Department Agriculture and Consumer Services, marking 32 confirmed strangles cases in the state so far in 2022.
Finally, a 6-year-old Quarter Horse mare tested positive in Mecosta County, Michigan, on May 18. The Michigan Department of Agriculture and Rural Development reported the horse was unvaccinated and presented on April 26 with a fever and a submandibular abscess. She is reported to be 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.