APHIS Factsheet

Veterinary Services May 2012

Vesicular Stomatitis

Vesicular stomatitis is a viral disease that primarily 

affects horses and cattle and occasionally swine, sheep, 

goats, llamas, and alpacas. Humans can also become 

infected with the disease when handling affected 

animals, but this is a rare event. Vesicular stomatitis 

has been confi rmed only in the Western Hemisphere. 

It is known to be an endemic disease in the warmer 

regions of North, Central, and South America, but outbreaks of the disease in other temperate geographic 

parts of the hemisphere occur sporadically.

In the past decade, the Southwestern and Western 

United States have experienced a number of vesicular 

stomatitis outbreaks. Outbreaks usually occur during 

the warmer months, often along waterways. In some 

years, only a few premises in a single State have been 

affected. However, in other years, multiple States and 

many premises have been involved.

Since there could be a vesicular stomatitis outbreak 

in any given year, it is essential that veterinarians and 

livestock owners be on the alert for animals displaying 

clinical signs of the disease. For current information 

on vesicular stomatitis outbreaks or summaries of the 

most recent past outbreaks, please visit the APHIS 

Web site at www.aphis.usda.gov/vs/nahss/equine/vsv/.

Economic Impacts

While vesicular stomatitis does not generally cause 

animals to die, it can still cause economic losses to 

livestock producers. The disease is particularly signifi -

cant because its outward signs are similar to (although 

generally less severe than) those of foot-and-mouth 

disease, a foreign animal disease of cloven-hoofed 

animals that was eradicated from the United States in 

1929. The clinical signs of vesicular stomatitis are also 

similar to those of swine vesicular disease, another 

foreign animal disease. The only way to tell these 

diseases apart is through laboratory tests.

Vesicular stomatitis is recognized internationally as a 

reportable disease. This means that there are serious 

economic and regulatory repercussions associated 

with the diagnosis. When the disease is detected in 

the United States, some countries may take action to 

block international trade of U.S. animals and animal 

products. Interstate movement of animals is also 

impacted. Premises containing affected animals are 

quarantined until 21 days after the lesions in the last 

affected animals have healed. As a result, quarantine 

periods can be lengthy.

Clinical Signs

In affected livestock, the incubation period for vesicular 

stomatitis ranges from 2 to 8 days. Often, excessive 

salivation is the fi rst sign of the disease. Close examination of the mouth initially reveals blanched and raised 

vesicles or blister-like lesions on the inner surfaces of 

the lips, gums, tongue, and/or dental pad. In addition, 

these blister-like lesions can form on the lips, nostrils, 

coronary band, prepuce, vulva, and teats. The blisters 

swell and break, which causes oral pain and discomfort 

and reluctance to eat or drink. Lameness and severe 

weight loss may follow. Body temperature may rise 

immediately before or at the same time lesions fi rst 

appear. 

Dairy cattle often suffer from teat lesions and subsequent mastitis; a severe drop in milk production commonly occurs. Some affected dairy cattle can appear 

to be normal with no clearly visible signs of illness but 

may only eat about half of their normal feed intake. If 

there are no complications such as secondary infection, 

affected animals typically recover in about 2 weeks.

In horses, vesicular lesions generally occur on the 

upper surface of the tongue, the lips, around nostrils, 

corners of the mouth, and gums. Lesions in horses 

may also be expressed as crusting scabs on the 

muzzle, lips, or ventral abdomen. 

Affected pigs usually fi rst show signs of lameness 

caused by foot lesions.

Disease Spread

How vesicular stomatitis spreads is not fully known; 

insect vectors, mechanical transmission, and movement of animals are all factors. Once the disease is 

introduced into a herd, it may move from animal to 

animal by contact or exposure to saliva or fl uid from 

ruptured vesicles. Humans rarely contract vesicular 

stomatitis, but they can become infected.

In people, the disease causes an acute infl uenza-like 

illness with symptoms such as fever, muscle aches, 

headache, and malaise. To avoid exposure to this 

disease, individuals should use personal protective 

measures when handling affected animals.
Recommended Actions

There is no specifi c treatment or cure for vesicular 

stomatitis. Good sanitation and quarantine practices 

on affected farms usually contain the infection.

When a defi nite diagnosis is made on a farm, the 

following procedures are recommended:

• Separate animals with lesions from healthy animals, 

preferably by stabling. Animals on pastures tend to 

be affected more frequently with this disease.

• As a precautionary measure, do not move animals 

from premises affected by vesicular stomatitis until 

at least 21 days after lesions in the last affected 

animal have healed.

• Implement on-farm insect control programs that 

include the elimination or reduction of insect breeding areas and the use of insecticide sprays or 

insecticide-treated eartags on animals.

• Use personal protective measures when handling 

affected animals to avoid human exposure to this 

disease.

Report Suspicious Cases

Veterinarians and livestock owners who suspect an 

animal may have vesicular stomatitis or any other 

vesicular disease should immediately contact State 

or Federal animal health authorities. Diagnosis of the 

disease cannot be made based on clinical signs but 

requires testing of samples at a facility approved by the 

U.S. Department of Agriculture’s National Veterinary 

Services Laboratories in Ames, IA.

A diagnosis can be based on antibody tests using 

serum samples from the animal and/or by detecting 

virus from swabs of lesions, blister fl uid, and tissue 

(fl aps, biopsies). A diagnosis can generally be made in 

a week or less.

Additional Information

For more information, contact the: 

U.S. Department of Agriculture

Animal and Plant Health Inspection Service

Veterinary Services

National Center for Animal Health Emergency Management

4700 River Road, Unit 41

Riverdale, MD 20737-1231

Phone: (301) 851-3595

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United States Department of Agriculture • Animal and Plant Health Inspection Service • Safeguarding American Agriculture