Vesicular Stomatitis Outbreak Update

Five new premises in California have confirmed or suspected cases of vesicular stomatitis virus (VSV), and four premises have been released from quarantine.
Five new premises in California have confirmed or suspected cases of vesicular stomatitis virus (VSV), and four premises have been released from quarantine.
Five new premises in California have confirmed or suspected cases of vesicular stomatitis virus (VSV), and four premises have been released from quarantine. | Wikimedia Commons

Since the last report on June 30, there have been five new vesicular stomatitis-affected premises identified in California. There are six counties currently affected in California: Los Angeles, Orange, Riverside, San Bernardino, San Diego and Ventura. The one affected premises in Maverick County, Texas, was released from quarantine on June 27. All confirmed cases have been vesicular stomatitis New Jersey virus (VSNJV) serotype. Updates are as follows:  

  • In Los Angeles County, there are three new suspect equine premises.
  • In San Bernardino County, there is one new suspect equine premises.
  • In San Diego County, there is one new confirmed equine premises.

Since the last report, three premises in Riverside County and one premises in San Diego County have been released from quarantine.

Since the start of the outbreak on May 17, 119 VSV-affected premises have been identified (40 confirmed positive, 79 suspect) in two states, California and Texas. Of the 119 total VSV-affected premises, 63 premises have completed the quarantine period with no new clinical cases and have been released from quarantine. Fifty-six premises remain quarantined.

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.

About Vesicular Stomatitis 

Vesicular stomatitis is a viral disease of horses, donkeys, mules, cattle, swine and New World camelids that occurs in the Western Hemisphere. It is named for the characteristic vesicular lesions it causes in the form of blisters, crusts and ulceration of the lips, muzzle, nose, tongue, ears, sheath, teats and/or coronary band. The virus is transmitted by biting midges and therefore is seasonal.

Clinical Signs for vesicular stomatitis include:

  • Vesicle formation leading to ulcerative lesions on the lips, muzzle, nostrils and tongue. The tongue is often the most severely affected area.
  • Ulceration of the inner surface of the lips.
  • Crusting of the muzzle, nostrils, and/or inside the ears.
  • Excessive salivation secondary to the oral lesions.
  • Difficulty picking up and chewing feed.
  • Lameness due to painful erosions on the coronary band.
  • Lesions can occur on the udder, sheath and inside of the ear.
  • Lesions can develop secondary infections resulting in slow-to-heal wounds.
  • Animals on pastures are at increased risk of vesicular stomatitis.

Initial diagnosis is based on recognition of characteristic vesicular lesions. Infection is confirmed via laboratory testing for serum antibodies and/or virus identification in fluid samples from active lesions. Veterinarians are required to report suspected cases to state/federal animal health officials who will direct sample submission to an approved regulatory laboratory for diagnostic testing. 

There is no specific treatment for vesicular stomatitis. Best practices include implementing good biosecurity and treating affected horses with pain relievers, anti-inflammatories and supportive care as recommended by a veterinarian.

Isolating all affected animals and placing the premise on immediate quarantine is required until all horses have fully recovered and no active lesions are present. The State Veterinarian will work with the local veterinarian to determine and implement necessary quarantine procedures.

Brought to you by Boehringer Ingelheim, The Art of the Horse

Lainey Ashker’s Top Tips for a Shiny, Healthy Coat
White horse eye
3 EIA Cases Confirmed in Texas
Horse on meadow
Quebec Horse Tests Positive for WNV
Brown horse head of bay mare with water dripping from face, anim
Michigan Mare Tests Positive for Strangles
Don’t miss an important EDCC Health Alert! Get alerts delivered straight to your inbox by signing up for Practical Horseman’s newsletter.

"*" indicates required fields


Additional Offers

Additional Offers
This field is for validation purposes and should be left unchanged.