Two Arizona Horses Test Positive for Vesicular Stomatitis
On October 31, the National Veterinary Services Laboratories confirmed the presence of the vesicular stomatitis New Jersey virus (VSNJV) in two separate horse premises in Cochise County, Arizona. This discovery marks a significant development in the ongoing battle against vesicular stomatitis, a viral disease affecting various animals.
At one property, a 21-year-old grade mare tested positive, while at the other, an 8-year-old Quarter Horse gelding was found infected. Both horses are considered index cases for the 2025 VSV outbreak in the United States. Interestingly, the last major outbreak occurred between May 2023 and January 2024, impacting 319 premises across California, Nevada, and Texas. Vesicular stomatitis is a recurring issue, with the virus circulating annually between livestock and insect vectors in southern Mexico and occasionally spreading to the U.S.
The Equine Disease Communication Center (EDCC) plays a crucial role in this scenario. EDCC Health Watch, an EDCC marketing program, disseminates verified equine disease reports. The EDCC is an independent nonprofit organization, supported by industry donations, that provides open access to infectious disease information. This transparency is vital for managing and preventing the spread of diseases like vesicular stomatitis.
Vesicular stomatitis is a viral disease affecting horses, donkeys, mules, cattle, swine, and New World camelids, primarily in the Western Hemisphere. It gets its name from the characteristic vesicular lesions it causes, including blisters, crusts, and ulcerations on various body parts like the lips, muzzle, nose, tongue, ears, sheath, teats, and coronary band. The virus is transmitted by biting midges, making it a seasonal concern.
Clinical signs of vesicular stomatitis include vesicle formation, leading to ulcerative lesions on the lips, muzzle, nostrils, and tongue, with the tongue often being the most affected. Other symptoms include ulceration of the inner lip surface, crusting of the muzzle and nostrils, excessive salivation, difficulty in feeding, lameness due to coronary band erosions, and lesions on the udder, sheath, and ear. These lesions can lead to secondary infections, making the disease a serious concern for animal health.
Diagnosis involves recognizing characteristic vesicular lesions, followed by laboratory testing for serum antibodies and/or virus identification in fluid samples. Veterinarians must report suspected cases to state/federal animal health officials, who will direct sample submission to an approved regulatory laboratory for diagnostic testing. Unfortunately, there is no specific treatment for vesicular stomatitis, but implementing good biosecurity and providing supportive care, as recommended by a veterinarian, is essential.
To control the outbreak, all affected animals must be isolated and placed under immediate quarantine until they have fully recovered and no active lesions are present. The State Veterinarian, in collaboration with local veterinarians, will determine and enforce the necessary quarantine procedures to prevent further spread.
