Since November 2022, there have been reported cases of strangles in nine Wisconsin counties. Below is an overview of confirmed cases and potential exposures.
In La Crosse County, a yearling Quarter Horse filly who was rescued from a kill pen a few months ago was sampled on January 30 and reported on February 6. She had a low-positive PCR and had previously experienced nasal discharge. Ten to 15 other horses are located on the premises without clinical signs. The affected horse is under voluntary quarantine.
In Waushara County, a 7-month-old Morgan filly tested positive and was reported on January 9. The filly had respiratory signs and abscessed lymph nodes. A 33-year-old Arabian gelding at the same boarding facility was sampled on January 30 and also tested positive. He displayed respiratory signs and nasal exudate. There are 17 equines on the premises, seven of which are exposed and six of which exhibited clinical signs. The likely source of the outbreak was a new rescue horse that arrived on December 5. The rescue horse showed clinical signs shortly after arrival and was treated but not tested. The affected horses are under voluntary quarantine.
In Jefferson County, a 12-year-old Mustang cross mare is suspected positive for strangles and was reported on January 6. The horse was recently acquired from a kill pen and is wild, so it could not be caught for testing. It is displaying clinical signs, including swelling of the throatlatch, cough and lymph node abscessation. There are six other horses on the premises from which the sick mare is isolated.
In Washington County, an 18-year-old Quarter Horse cross gelding from an in-state rescue developed clinical signs, including nasal discharge and fever, on December 13 and was reported on December 21. Voluntary quarantine was recommended but only partially followed. There are 15-20 other equines at the boarding stable, and five or six were exposed.
Also in Washington County, a 22-year-old pony mare at a boarding stable developed clinical signs on December 20, including decreased appetite, fever, nasal discharge and lymph node abscessation. The mare had a positive PCR test and was placed under voluntary quarantine.
In Dane County, an 8-year-old American Paint Horse gelding developed clinical signs on November 28 and was reported on December 19. The horse displayed a non-productive cough, fever and respiratory signs. Two other horses were potentially exposed when the horse traveled to a show barn for farrier work approximately 3.5 weeks prior to symptoms. The horse was placed under voluntary quarantine.
Also in Dane County, a 25-year-old mini-donkey mare developed mucopurulent nasal discharge, mild lethargy, fever and moderate appetite loss on December 24. The mare tested positive for strangles, which was reported on December 29. Another equine, who was a rescue, developed clinical signs and tested positive approximately three weeks prior. There are approximately 20 equines located on the premises. The affected horses are under voluntary quarantine.
On February 3, two geldings (an Arabian and a Morgan cross) were reported positive for strangles in Dane County after being sampled on January 27. The horses reside at a boarding stable, where approximately 100 horses are exposed. Strangles is reportedly going through the barn, where at least five new boarders have arrived in the last few months. The affected horses are under voluntary quarantine.
In Columbia County, a 4-year-old Quarter Horse gelding developed clinical signs on November 29, including fever, occasional cough, mild mucoid nasal discharge and serous ocular discharge. The horse had a history of transport within the previous two weeks. It was qPCR positive and placed under voluntary quarantine. Two other exposed horses were suspected positive but tested negative.
In Winnebago County, a 10-year-old Morgan gelding was sampled in November after developing fever, nasal discharge and abscessed lymph nodes. The gelding tested positive and was reported on December 16. The boarding stable where the horse is located has 10-20 other horses, three of which are positive for strangles. The affected horses are under voluntary quarantine.
In Oneida County, two equines are confirmed positive for strangles, a 5-year-old jenny mule and a 7-year-old Quarter Horse mare. They were reported on January 2.
In Lincoln County, an 18-year-old Quarter Horse mare tested positive in the fall after developing mucopurulent nasal discharge and dependent edema. The horse recovered with treatment and had a negative culture on December 6. Six other horses did not show any symptoms.
Also in Lincoln County, a 10-year-old Quarter Horse mare at a private facility tested positive. The horse was placed in a separate pasture under voluntary quarantine, and good biosecurity procedures were followed.
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.