Vesicular Stomatitis in Cows: Oral Ulcers, Drooling, and Reportable Disease Concerns

Vesicular stomatitis is a contagious viral disease that mainly affects cattle and horses. In cows, it often causes painful blister-like lesions that quickly rupture, so pet parents and producers may notice ulcers, erosions, drooling, and reluctance to eat rather than intact blisters. Lesions can affect the lips, tongue, dental pad, muzzle, teats, and the coronary bands above the hooves. Because the mouth and feet can both be involved, some cows also become lame.

This condition matters for two reasons. First, the sores can be painful enough to reduce feed intake, water intake, weight gain, and milk production. Second, vesicular stomatitis can look very similar to foot-and-mouth disease, which is why it is treated as a serious reportable disease concern until testing says otherwise. Your vet may recommend immediate isolation and may need to contact animal health officials.

In most cattle, vesicular stomatitis is self-limiting, meaning the infection often improves over time with supportive care. Even so, herd-level consequences can be significant because movement restrictions, quarantine, extra labor, and insect control can add stress and cost. People handling affected cattle should also use care, because the virus can occasionally infect humans through direct contact with lesions.

Vesicular stomatitis is caused by vesicular stomatitis virus (VSV), a virus in the genus Vesiculovirus. In the United States, outbreaks are often linked to biting insects, especially black flies, sand flies, and biting midges. Disease activity tends to rise in warmer months and in areas near waterways, where insect exposure can be heavier.

Spread can happen in more than one way. Infected cattle may pass virus through direct contact with lesions or saliva, and contaminated equipment, tack, feed areas, or handlers can also help move the virus between animals or premises. Insect vectors appear to play an important role in maintaining and spreading outbreaks, which is why fly control is a major part of prevention.

Not every cow exposed to the virus becomes severely ill. Age, lesion location, herd density, insect pressure, and overall stress may influence how obvious the disease becomes. The challenge is that the visible signs are not unique to vesicular stomatitis. Other conditions, including foot-and-mouth disease, parapoxvirus infections, and some regional vesicular or ulcerative diseases, can look similar at first glance. That is why your vet should guide the next steps instead of trying to sort it out by appearance alone.

Diagnosis starts with a same-day veterinary exam and herd history. Your vet will look closely at the mouth, muzzle, teats, and feet, ask when signs started, and assess whether other cattle are affected. Because vesicular stomatitis can be clinically indistinguishable from foot-and-mouth disease in cattle, a suspicious case is handled as a reportable vesicular disease concern until laboratory testing clarifies the cause.

Your vet may contact State or Federal animal health officials right away. Depending on the situation, samples may be collected from vesicular tissue, lesion swabs, or other approved specimens and sent to an authorized laboratory. Merck notes that confirmation may involve PCR, complement fixation testing, and/or virus isolation at an approved reference laboratory. During this period, the premises may be placed under movement restrictions or quarantine.

Diagnosis also includes ruling out look-alike conditions. Important differentials can include foot-and-mouth disease, bovine papular stomatitis, pseudocowpox, bluetongue or epizootic hemorrhagic disease in some regions, trauma, and other causes of oral or teat lesions. This is one of those situations where quick reporting protects both your herd and the wider livestock community.

Prevention focuses on biosecurity and insect control. Because biting flies and midges are important in transmission, reducing insect exposure matters. Work with your vet on a practical plan that may include manure management, drainage improvement, fly control products, physical barriers where possible, and extra attention to cattle housed near water or in heavy insect seasons.

If a new animal is coming onto the property, quarantine and observe before mixing with the herd. If a cow develops suspicious drooling or oral lesions, separate that animal right away and avoid sharing equipment, buckets, halters, or handling tools until your vet gives guidance. Handle healthy cattle before affected cattle, and wash or disinfect boots, hands, and equipment after contact.

There is no widely used approved field vaccine strategy for cattle in the U.S., so prevention depends mainly on management. During regional outbreaks, your vet may recommend postponing movement, shows, sales, or other events that increase contact risk. Fast reporting is also part of prevention. Early recognition can limit spread within the herd and reduce the chance of wider movement restrictions.