Arizona is currently experiencing an outbreak of vesicular stomatitis New Jersey virus (VSNJV). The National Veterinary Services Laboratories confirmed cases in horses on multiple premises in Cochise County, Gila County, and Santa Cruz County. A new case was also detected in a wild horse from the Salt River Wild Horse Management Group in Maricopa County.
Throughout December and January, additional affected equine premises were identified in Santa Cruz, Maricopa, and Pinal Counties. The latest report confirms a new VSV-positive premises in Maricopa County, while a previously affected premises in Santa Cruz County has been released from quarantine.
The previous outbreak of VSV in the U.S. affected 319 premises across California, Nevada, and Texas from May 2023 to January 2024. VSV typically circulates between livestock and insect vectors in southern Mexico and occasionally enters the U.S.
EDCC Health Watch, supported by the Equine Disease Communication Center (EDCC), provides verified equine disease reports. The EDCC is a nonprofit organization supported by industry donations for open access to infectious disease information.
About Vesicular Stomatitis
Vesicular stomatitis is a viral disease affecting horses, donkeys, mules, cattle, swine, and New World camelids in the Western Hemisphere. It causes vesicular lesions on various body parts and is transmitted by biting midges.
Clinical signs of vesicular stomatitis include:
- Vesicle formation leading to ulcerative lesions on the lips, muzzle, nostrils, and tongue.
- Ulceration of the inner surface of the lips.
- Crusting of the muzzle, nostrils, and inside the ears.
- Excessive salivation and difficulty picking up feed.
- Lameness from painful erosions on the coronary band.
- Lesions on the udder, sheath, and inside the ear.
- Potential secondary infections and slow wound healing.
- Increased risk for animals on pastures.
Diagnosis involves recognizing characteristic vesicular lesions and confirming infection through laboratory testing. Treatment focuses on biosecurity measures, pain relief, anti-inflammatories, and supportive care as prescribed by a veterinarian.
Isolation and quarantine of affected animals are essential until all horses have fully recovered and no active lesions are present, following guidance from State Veterinarians and local authorities.