A strangles outbreak has placed a boarding stable in northern Los Angeles County, Calif., under quarantine, and more than 60 horses at the farm remain under close observation. The outbreak of the highly contagious upper respiratory disease caused by the Streptococcus equi bacterium flared up at the stable in November 2004, and the L.A. County Department of Health Services (LADHS) Disease Control division began the stable lockdown the week of March 13.

“We were informed of the outbreak about four months into the situation,” said Patrick Ryan, DVM, chief veterinarian for LADHS. “We’ve alerted most of (the horse owners in) north Los Angeles County regarding the outbreak, telling them they should continue to guard their horses against the disease.” Only the infected stable was quarantined.

“The horses that are most at risk are the younger horses, two years old and younger, because they haven’t usually been exposed. Previous exposure helps develop immunity,” Ryan said. “Many times they have not even been vaccinated for strangles.” How long a strangles vaccine confers immunity depends on many factors, and horse owners should consult with their veterinarian on how often they should vaccinate.  

Strangles is spread by inhalation or ingestion of S. equi found in the nasal discharge or pus from draining abscesses of infected animals. The bacteria can be spread by close contact, flies, contact with contaminated equipment, or even on the clothing of owners caring for infected horses. Not all infected horses become ill. Protect your horses by isolating new horse arrivals at your farm for two to four weeks before allowing them to mingle with your herd and also keep your horses’ vaccinations current. Strict disinfection measures can help eliminate sources of infection if strangles hits your barn. For more information on strangles, see www.TheHorse.com/ViewArticle.aspx?ID=4710