USDA’s Animal and Plant Health Inspection Service has released a situation report on vesicular stomatitis virus (VSV) after the virus was identified on two Arizona farms this month.
While both reported cases were in horses, VSV also affects cattle, swine and other ruminants. The farms on which the virus was identified both also house cattle, though none have been found to be clinically affected.
In response to this outbreak, the Canadian Food Inspection Agency (CFIA) has announced temporary import restrictions on horses, ruminants and swine from the U.S. until further notice. The import of horses, swine and ruminants from VSV-affected states for all purposes is prohibited. Animals from other states that have been in a VSV-affected state at any point in the three weeks prior to import will be denied entry to Canada. Special accommodations have been made in collaboration with USDA regarding animal import for major Canadian livestock competitions and exhibitions.
What is Vesicular Stomatitis?
Vesicular stomatitis (VS) is a viral disease primarily spread by biting midges and flies, but can also be spread via animal-to-animal contact or exposure to saliva or fluid from ruptured vesicles. It is also important to protect yourself if working with infected animals as it is transmissible to humans causing an acute influenza-like illness.
VS is named for its characteristic vesicular lesions that form around the mouth, nose, udders and hooves. Along with these lesions, clinical signs of VS include:
- excessive salivation (often accompanied by raised blisters on the lips, gums and tongue)
- fever
- feed withdrawal leading to weight loss
In cattle and horses, lesions around the hooves can lead to lameness, while teat lesions in dairy cattle can lead to mastitis and a severe drop in milk production. Affected swine usually first show signs of lameness caused by foot lesions.
Controlling Vesicular Stomatitis
While VS does not usually cause the death of an animal, it can lead to economic losses due to prevented animal movement and impacts on international trace. Farms with VSV positive animals must quarantine for 14 days after lesions appear on the last case at the location.
The last VS outbreak occurred from May 2023 through January 2024 affecting 319 locations across California, Nevada and Texas. VSV circulates annually between livestock and insect vectors in southern Mexico, only entering the U.S. when environmental factors support the northern movement of vectors.
If you suspect an animal might be infected with VSV, you should immediately contact local state and federal animal health authorities.
