Vesicular Stomatitis in Horses and Cattle: Signs and What To Do

By Dr Duncan Houston

Blisters, drooling, mouth sores, and lameness in horses or cattle should never be brushed off as “just a sore mouth.”

Vesicular stomatitis, often shortened to VS or VSV, is a contagious viral disease that can affect horses, cattle, pigs, camelids, sheep, goats, and occasionally people. In many animals it is not fatal, but it matters because it can look very similar to foot-and-mouth disease in susceptible livestock, and that has major animal health and trade implications. USDA APHIS notes that vesicular stomatitis can affect animal movement and international trade even though high mortality is uncommon. (APHIS)

The practical message is simple: if you see blister-like lesions around the mouth, nose, teats, sheath, or coronary bands, call your vet before moving the animal or taking it to an event.

Quick Answer

Vesicular stomatitis is a reportable viral disease that causes painful blisters, ulcers, drooling, reluctance to eat, fever, and sometimes lameness in horses, cattle, and other livestock. It spreads through biting insects, direct contact with infected animals, and contaminated equipment or surfaces. Suspected cases need veterinary assessment and laboratory testing because the signs can resemble serious foreign animal diseases such as foot-and-mouth disease. (MSD Veterinary Manual)

What Is Vesicular Stomatitis?

Vesicular stomatitis is a viral disease caused by vesicular stomatitis viruses in the genus Vesiculovirus.

The disease is best known for causing vesicles, which are blister-like lesions. These blisters often rupture quickly, leaving painful erosions or ulcers. In horses, owners may never see intact blisters because they can burst before the animal is examined.

Common lesion sites include:

• Tongue

• Lips

• Gums

• Dental pad in cattle

• Muzzle

• Nose

• Udder or teats

• Sheath

• Coronary bands near the hooves

USDA APHIS lists drooling, frothing at the mouth, blister-like lesions, fever, and reluctance to eat as key signs, with lameness possible when lesions develop around the coronary band. (APHIS)

The disease often causes more disruption than death. The welfare issue is pain, reduced eating or drinking, lameness, secondary infection, and dehydration. The wider industry issue is movement restriction and disease investigation.

Why Does Vesicular Stomatitis Matter So Much?

Vesicular stomatitis matters because it can look like other vesicular diseases that are far more serious.

In cattle and pigs especially, vesicular stomatitis can be clinically difficult to distinguish from foot-and-mouth disease, swine vesicular disease, or vesicular exanthema of swine. MSD Veterinary Manual states that diagnostic testing at an approved regulatory laboratory is needed for definitive diagnosis. (MSD Veterinary Manual)

That is why suspected VS is not handled like a routine mouth ulcer.

If a horse or cow has suspicious blisters or erosions, the issue is not just “how do we make this animal comfortable?” It is also “could this be a reportable disease that affects animal movement, neighbouring properties, shows, sales, and trade?”

In practice, this is where owners can accidentally make things worse by moving animals before calling a vet.

Which Animals Can Get Vesicular Stomatitis?

The main domestic species of concern include:

• Horses

• Donkeys

• Mules

• Cattle

• Swine

• Camelids, including llamas and alpacas

• Sheep and goats, less commonly

USDA APHIS lists equids and cattle as primary susceptible species, with camelids, swine, sheep, and goats also susceptible. (APHIS)

People can also become infected, although this is uncommon. In humans, VS is usually a short, flu-like illness, but direct contact with lesions, saliva, or vesicular fluid should still be avoided. MSD Veterinary Manual notes that people exposed to the virus can develop a self-limiting influenza-like illness with headache, fever, muscle pain, and weakness lasting about 3 to 5 days. (MSD Veterinary Manual)

So this is not just an animal-to-animal biosecurity issue. It is also a handling and personal protective equipment issue.

How Does Vesicular Stomatitis Spread?

Vesicular stomatitis can spread in several ways.

Important routes include:

• Biting insects

• Direct contact with infected animals

• Contact with saliva or fluid from ruptured lesions

• Contaminated buckets, feeders, tack, trailers, equipment, bedding, or surfaces

• Movement of animals from affected premises

Known competent insect vectors include black flies, sand flies, and biting midges, although other insects may also play a role. MSD Veterinary Manual also notes direct contact with clinically affected animals as a transmission route. (MSD Veterinary Manual)

Outbreaks are more likely in warmer months and are often associated with insect activity and waterways. USDA APHIS notes that outbreaks usually occur during warmer months, often along waterways, and that the Southwestern and Western United States have experienced several outbreaks since 1995. (APHIS)

The disease is not simply “spread by dirty barns.” Fly pressure, climate, animal movement, water sources, and local outbreak status all matter.

What Are the Signs of Vesicular Stomatitis?

The first sign owners notice is often drooling.

A horse may stand with saliva dripping from the mouth, refuse feed, dunk hay in water, chew awkwardly, or act uncomfortable when eating. Cattle may salivate heavily, go off feed, drop milk production, or become lame if foot lesions are present.

Common signs include:

• Excessive drooling or frothing

• Blisters in or around the mouth

• Ruptured ulcers on the tongue, lips, gums, or dental pad

• Sores around the muzzle or nostrils

• Fever

• Reluctance to eat or drink

• Weight loss if signs persist

• Lameness from coronary band lesions

• Lesions on the udder, teats, or sheath

• Reduced milk production in lactating animals

• Depression or reduced performance

UC Davis notes that lesions can develop in and around the mouth, then rupture into painful ulcers, and that lesions may also occur on the udder, sheath, and coronary bands. (Center for Equine Health)

The signs can be mild in one animal and more obvious in another. That variability is one reason suspected cases need a proper veterinary assessment.

How Worried Should You Be?

Vesicular stomatitis is often not fatal, but it should still be treated seriously because it is painful, contagious, reportable in many places, and hard to distinguish from more serious diseases without testing.

The key point is this: the animal may recover, but the property may still need movement restrictions and official disease investigation.

That is why early communication matters.

Is It Vesicular Stomatitis or Something Else?

Not every mouth sore is vesicular stomatitis.

Possible causes and rule-outs include:

• Dental trauma

• Sharp feed material or oral foreign bodies

• Chemical irritation

• Oral ulcers from toxic plants or irritants

• Foot-and-mouth disease in susceptible species

• Bovine viral diarrhoea in cattle

• Infectious bovine rhinotracheitis in cattle

• Bluetongue or other vesicular or ulcerative diseases

• Photosensitisation affecting muzzle skin

• Foot rot or sole abscess if lameness is the main sign

• Teat trauma or mastitis if teat lesions are present

• Poxvirus or other skin diseases in some species

In horses, vesicular stomatitis is often suspected when mouth lesions and drooling occur during an outbreak season or in an affected region. In cattle and pigs, the need to rule out foot-and-mouth disease becomes especially important because the outward signs can overlap. MSD Veterinary Manual emphasises that diagnostic testing is required for definitive diagnosis. (MSD Veterinary Manual)

The mistake is assuming you can tell by appearance alone.

You usually cannot.

How Do Vets Diagnose Vesicular Stomatitis?

Diagnosis starts with the clinical signs, location, species involved, local outbreak status, and movement history.

Your vet may ask:

• When did drooling or lesions first appear?

• Have any animals recently travelled?

• Have any new animals arrived?

• Are neighbouring properties affected?

• Are multiple species involved?

• Are there lesions on the mouth, feet, teats, or sheath?

• Has the animal been to shows, sales, clinics, breeding farms, or events?

• Are insects heavy around the property?

• Are animals kept near waterways?

Testing may include lesion swabs, vesicular fluid, tissue tags from lesions, blood samples, and laboratory tests to detect virus, viral genetic material, or antibodies. MSD Veterinary Manual describes diagnosis using typical clinical signs plus serology, virus isolation, or molecular detection. (MSD Veterinary Manual)

Because VS is a reportable disease in the United States, suspected cases should be reported to state and federal animal health officials. (MSD Veterinary Manual)

This is not a disease where the owner should quietly “wait and see” while continuing normal movement.

What Happens if Vesicular Stomatitis Is Suspected?

The first step is usually isolation and official guidance.

If VS is suspected, your vet may contact animal health authorities. Depending on the location and current outbreak status, officials may arrange testing, issue movement restrictions, and provide instructions for the affected property.

Confirmed and presumptive positive premises in the USDA APHIS 2025 situation report were quarantined for at least 14 days from the onset of lesions in the last affected animal on the premises. (APHIS)

General control steps may include:

• Isolating affected animals

• Restricting movement from the property

• Monitoring exposed herd mates

• Using gloves and eye protection when handling lesioned animals

• Cleaning and disinfecting equipment

• Reducing insect exposure

• Preventing shared buckets, feeders, tack, or grooming tools

• Following state or federal quarantine instructions

AAEP guidance notes that movement restriction is important and that confirmed affected premises are subject to mandatory quarantine by state or federal animal health officials.

The exact rules can vary by jurisdiction and outbreak status, so the safest move is always to call your vet before travelling, showing, selling, or moving animals.

When Is This an Emergency?

Vesicular stomatitis itself is not always a same-minute medical emergency, but suspected cases can become urgent for welfare, biosecurity, and regulatory reasons.

Call your vet urgently if you see:

• Blisters or ulcers on the mouth, tongue, lips, muzzle, teats, sheath, or coronary bands

• Excessive drooling or frothing

• A horse or cow refusing to eat or drink

• Lameness with coronary band lesions

• Fever with mouth or foot lesions

• Multiple animals affected

• Rapid spread through a property

• Lesions in cattle, pigs, or mixed livestock groups

• Severe dehydration

• Marked depression or weakness

• Suspicious lesions after recent travel, shows, sales, or new arrivals

Do not move the animal to a show, clinic, sale, breeding farm, or another property unless your vet or animal health officials tell you to do so.

That includes “just taking them somewhere for someone to look at it.” With vesicular diseases, movement can turn one property’s problem into a regional problem.

What Should You Do Right Now?

If you suspect vesicular stomatitis, act like it is contagious until proven otherwise.

1. Isolate the affected animal.
   Move them away from healthy animals if you can do so safely, or create separation where they already are.

2. Stop animal movement.
   Do not haul affected or exposed animals off the property.

3. Call your veterinarian.
   Tell them you are seeing drooling, blisters, mouth ulcers, teat lesions, or coronary band lesions.

4. Avoid direct contact with lesions.
   Wear gloves. Eye protection is sensible when examining or handling affected horses because exposure to saliva or vesicular fluid can infect people. AAEP specifically recommends gloves, hand washing, and eye protection when working with affected horses.

5. Use separate equipment.
   Do not share buckets, feeders, grooming tools, tack, halters, milking equipment, or trailers.

6. Control insects.
   Reduce fly breeding areas, use appropriate repellents or insecticides, stable during peak insect activity if useful, and keep animals away from high-risk wet areas when possible.

7. Provide soft feed and easy water access.
   Mouth ulcers can make eating and drinking painful.

8. Follow official instructions.
   If the premises is quarantined, follow the rules exactly.

The real goal is to protect the affected animal while preventing spread.

How Is Vesicular Stomatitis Treated?

There is no specific antiviral cure for vesicular stomatitis.

Treatment is supportive and depends on the animal’s signs. MSD Veterinary Manual describes VS as self-limiting, with supportive care such as softened feeds, mild antiseptic cleansing of lesions to reduce secondary bacterial infection risk, and fluids for animals that will not drink adequately. (MSD Veterinary Manual)

Supportive care may include:

• Softened feed

• Clean, easy-to-access water

• Anti-inflammatory pain relief prescribed by your vet

• Mild cleaning of lesions if advised

• Treatment of secondary bacterial infection if present

• Fly control

• Rest from work or transport

• Monitoring hydration and appetite

• Support for animals with teat lesions, lameness, or weight loss

Do not use harsh chemicals in the mouth. Painful oral tissues can be made worse by strong disinfectants, irritating sprays, or random home remedies.

The best treatment is usually simple, careful, and boring. Unfortunately, “boring” rarely gets enough applause.

Can People Catch Vesicular Stomatitis?

Yes, but human infection is uncommon and usually mild.

People exposed to infected saliva, vesicular fluid, or laboratory material can develop flu-like illness. MSD Veterinary Manual describes human signs as headache, fever, muscle pain, weakness, and rarely vesicles on the mouth, lips, or nose. (MSD Veterinary Manual)

To reduce risk:

• Wear gloves when handling affected animals

• Avoid touching lesions directly

• Use eye protection when examining mouths or lesions

• Wash hands thoroughly

• Wash contaminated clothing

• Keep children and immunocompromised people away from affected animals

• Do not eat, drink, or touch your face while handling affected animals

This is not a reason to panic. It is a reason to use basic protective handling.

What About Shows, Sales, Transport, and Health Certificates?

VS can affect animal movement.

During outbreaks, some states, events, and facilities may require additional health certificate statements, recent veterinary inspections, oral exams, or restrictions on animals coming from affected areas. AAEP notes that during outbreaks there may be additional entry requirements for horses from regions where disease has been confirmed, including certificates of veterinary inspection with specific VS-related statements and inspection of arriving horses.

Before travelling, check:

• Current state animal health requirements

• Event entry rules

• Certificate of veterinary inspection requirements

• Recent outbreak notices

• Quarantine status of your property

• Whether your destination accepts animals from your region

• Whether exposed herd mates are restricted

Do this before loading the trailer. Discovering movement rules at the gate is the equine version of reading the instructions after assembling the furniture.

How Can You Reduce the Risk of Vesicular Stomatitis?

You cannot eliminate all risk, especially during active regional outbreaks, but you can reduce exposure.

Practical prevention steps include:

• Control biting insects

• Remove manure and wet organic material where insects breed

• Use fly traps, repellents, fans, screens, or insecticides where appropriate

• Stable animals during peak insect activity when helpful

• Avoid turnout near moving water during outbreak conditions if possible

• Isolate new or returning animals

• Avoid sharing buckets, tack, feeders, grooming tools, and trailers

• Disinfect shared equipment between animals

• Handle healthy animals before sick animals

• Wash hands, boots, and clothing after handling affected animals

• Monitor state and federal disease alerts

• Delay unnecessary travel during active outbreaks

• Keep good records of animal movement

USDA APHIS lists isolation of new horses, insect control, separating sick animals, handling healthy animals before sick animals, and washing or disinfecting hands and boots after handling sick animals as prevention steps. (APHIS)

There is no approved commercial vesicular stomatitis vaccine for horses in the United States. (APHIS)

So prevention is mainly biosecurity, insect control, and movement awareness.

Common Mistakes Owners Make

Assuming drooling is just a dental problem
Dental disease is common, but drooling with blisters or ulcers needs a vesicular disease rule-out.

Moving animals before calling the vet
Movement can spread disease and complicate quarantine investigations.

Sharing buckets and equipment
Saliva and fluid from lesions can contaminate surfaces and equipment.

Ignoring cattle or pigs because the horse looks worse
Foot-and-mouth disease concerns are especially important in cattle and pigs with vesicular signs.

Using harsh mouth treatments
Strong chemicals can damage painful oral tissues and may make eating even harder.

Forgetting personal protection
VS can infect people, so gloves, eye protection, and hand hygiene matter.

Waiting until several animals are affected
Early reporting protects the property, neighbouring farms, and the wider livestock community.

Will Affected Animals Recover?

Most animals recover with supportive care, but recovery time varies.

UC Davis notes that the prognosis in horses is generally good and that most cases resolve within a few weeks. (Center for Equine Health)

Outcome depends on:

• Severity of mouth lesions

• Whether the animal keeps eating and drinking

• Presence of lameness

• Secondary infection

• Age and underlying health

• Speed of isolation and supportive care

• Whether additional animals become affected

• Quarantine and movement restrictions

The biggest risks are usually pain, dehydration, reduced intake, lameness, production losses, secondary infection, and spread to other animals.

A bright horse with mild mouth ulcers may do well. A cow with severe oral pain, reduced drinking, teat lesions, and herd exposure needs much more careful management.

FAQs

Is vesicular stomatitis the same as foot-and-mouth disease?

No. Vesicular stomatitis and foot-and-mouth disease are different diseases. The problem is that their lesions can look similar in some livestock, especially cattle and pigs, so laboratory testing is needed to tell them apart. (MSD Veterinary Manual)

Is vesicular stomatitis reportable?

Yes, in the United States vesicular stomatitis is reportable to state and federal animal health officials, and affected premises may be quarantined to limit spread. (MSD Veterinary Manual)

How long is a property quarantined for vesicular stomatitis?

In USDA APHIS reporting, confirmed and presumptive positive premises are quarantined for at least 14 days from the onset of lesions in the last affected animal on the premises. Rules may vary by jurisdiction and outbreak status, so follow official instructions. (APHIS)

Can horses and cattle die from vesicular stomatitis?

Death is uncommon, but the disease can still cause pain, poor intake, weight loss, lameness, secondary infection, production losses, and major movement restrictions. Young, old, dehydrated, or medically fragile animals need closer monitoring.

Can humans get vesicular stomatitis?

Yes, people can become infected, usually after close contact with infected animals, lesions, saliva, or vesicular fluid. Human illness is usually flu-like and self-limiting, but gloves, eye protection, and good hygiene should be used when handling affected animals. (MSD Veterinary Manual)

Final Thoughts

Vesicular stomatitis is usually not the deadliest disease on the farm, but it is one of those diseases where the consequences go beyond the individual animal.

A drooling horse or cow with mouth ulcers may need pain relief and soft feed. But they may also need isolation, testing, reporting, quarantine, insect control, and movement restrictions.

The safest approach is clear: do not guess, do not haul, and do not keep it quiet. Call your vet, isolate the animal, protect yourself when handling lesions, and follow official guidance.

Most affected animals recover, but early recognition helps protect the whole property.

If you are unsure whether mouth sores, drooling, lameness, or teat lesions could be vesicular stomatitis, ASK A VET™ can help you decide how urgent it is and what to do next.