Vesicular stomatitis (VS) is a viral disease that primarily affects horses and cattle and occasionally swine, sheep, goats, llamas, and alpacas. Humans can also become infected with the disease when handling affected animals, but this is a rare event. Vesicular stomatitis has been conﬁrmed only in the Western Hemisphere. It is known to be an endemic disease in the warmer regions of North, Central, and South America, and outbreaks of the disease in other temperate geographic parts of the hemisphere occur sporadically. The Southwestern and Western United States have experienced a number of vesicular stomatitis outbreaks, the most recent and largest VS outbreak occurred in 2015. Outbreaks usually occur during the warmer months, often along waterways. The time from exposure to the onset of clinical signs is 2-8 days. VS is a state reportable disease.
VS is spread by insect vectors and direct contact with infected animals. Black flies, sand flies, and midges are the known vectors of this disease, but other insects may also be capable of transmission. Infected animals shed the virus from the lesions (blisters) they develop, so direct contact with infected animals or water, feed, buckets, and other fomites contaminated with saliva from infected animals can also transmit the disease. The virus can also be spread on shoes, clothing, hands, and contaminated equipment.
Practice good biosecurity and isolate new horses when introduced to the herd. Keeping insect population down may also help in the prevention of VS. There have been experimental vaccines developed but none have been approved for use in horses.
Collect swabs of the lesions and serum to be sent to the National Veterinary Services Laboratories (NVSL) for confirmation of an index case. In the event of an outbreak, your local NAHLN laboratory may become approved to test equine samples after the index case in your state is confirmed.
Set up a quarantine for the farm to help prevent spread of the disease. Ensure good biosecurity practices when handling sick and healthy horses. Use and advise your clients to use personal protective equipment when handling lesioned animals to prevent zoonotic transmission.