Western Washington Horse Tests Positive For Strangles

On Thursday, a horse in Washington’s Clark County, tested positive for strangles, a highly contagious bacterial infection that impacts the upper respiratory tract. Two other horses at the private facility are also suspected of having strangles, but that has yet to be confirmed. The horses are under veterinary care and the facility is under voluntary quarantine. It’s not known at this point how many other horses may have been exposed.

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:

Fever
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.

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