Vesicular somatitis has reared its ugly head again this summer in several U.S. states.
The infectious viral disease causes painful sores in a variety of animals including horses, cattle, pigs, bison, goats, sheep, alpacas and llamas.
Vesicular stomatitis virus attacks the muzzle skin, tongue, mouth, coronary band of hoofs, sheath and teats. Early lesions are fluid-filled, blister-like areas.
With trauma, the blisters rupture and slough leading to erosions.
Excessive drooling is most often the first sign of a problem.
Milk production frequently is re-duced in infected dairy cattle.
Affected animals may have reduced water and feed consumption with decreased weight gain.
Feeding soft hay or mash can en-courage affected animals to eat.
In animals with hoof lesions, short-term lameness can occur.
These infections are generally self-limiting and will heal without treatment within a few weeks.
Secondary bacterial infections can happen in some animals and may require antibiotic treatment.
Major virus transmission routes are thought to include direct contact between affected and naïve animals, fly bites and shared equipment.
There are no licensed vaccines in Canada or the United States.
So far this summer, Texas and Colorado are reporting confirmed cases.
Summer outbreaks occur almost annually in the southern states but can spread from there, likely through movement of infected animals.
The outbreak in 2005 saw cases as far north as Montana.
Reservoirs of vesicular stomatitis are thought to be located in central America, from where they spread northward each summer.
It seems to be a Western Hemisphere disease, with no cases de-scribed elsewhere in the world.
Properties are typically quarantined for 21 days to the let the viral disease run its course.
Good biosecurity to prevent disease spread includes isolating affected animals, disinfection and fly control.
Given that it is considered a mild disease with non-lethal effects on individual animal health, you may be surprised to learn that this outbreak has caused major transportation restrictions and quarantines.
It is a reportable disease in Canada and the U.S. This is because the lesions caused by vesicular stomatitis virus are identical to those of the dreaded foot and mouth disease.
In cattle and pigs with blister-like lesions, the only way to distinguish between these two diseases is to do diagnostic testing. Blood and fluid from unruptured blisters are the most frequently tested samples.
Horses are resistant to foot and mouth disease so this is a useful way to distinguish which disease is causing the problem while waiting for test results.
Quarantines include horses be-cause they can carry the virus and infect susceptible cloven-hoofed animals, creating a foot and mouth disease scare.
Early detection of foot and mouth disease is paramount because it is not present in Canada. Spread of this highly contagious disease would be economically devastating.
Canada can choose to implement importation restrictions on susceptible animals that could include veterinary examination and health certification. Animals from affected areas may be denied entry.
Major horse events are also affected.
Health certifications are required by shows including the American Quarter Horse Youth World Show.
If you are heading south for horse competitions this summer, be sure to check with event officials in case there are additional requirements.
Vesicular stomatitis can also rarely infect people, causing non-specific illnesses (muscle pains, fever, headache) and rarely blisters.
If concerned about lesions that might be vesicular stomatitis, contact your veterinarian.
Suspected cases must be reported to the CFIA for further investigation.
Although vesicular stomatitis isn’t a deadly disease, the most significant impact is on decreased production, transportation restrictions and in-ternational trade interruptions.
Dr. Jamie Rothenburger is a veterinary pathology resident at the Western College of Veterinary Medicine, University of Saskatchewan. Twitter: @DrJamieR_Vet