Virus Hits Livestock Hard in Colorado, Texas

Vesicular stomatitis has been confirmed in 11 Texas counties and eight counties in Colorado.

Rest, fluids and softened feeds are recommended for horses infected with vesicular stomatitis.


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Vesicular stomatitis, a contagious but rarely fatal livestock disease, has been diagnosed at nearly 190 locations across Colorado and Texas since the viral outbreak began in late May.

The U.S. Department of Agriculture reported Wednesday that 76 new premises, or locations, have been identified since Aug. 6. The new cases involved 105 horses, five head of cattle and three previously disease-free counties.

Two of the newly infected counties, Broomfield and Jefferson, are in Colorado, while the other is Williamson County, Texas.

“Veterinarians have been very observant and diligent to report horses and other livestock that are suspicious of being infected,” said the Colorado state veterinarian, Keith Roehr, DVM.

Livestock owners outside of Colorado and Texas should take precautions, said Elizabeth Davis, DVM, Ph.D., Dipl. ACVIM, a director of equine medicine and surgery at Kansas State University.

“It’s an interesting disease because it does have pretty significant clinical signs,” Dr. Davis said. “Most commonly, it causes painful oral blisters in horses that can affect the mouth, muzzle and tongue. Additional signs may include lesions on the udder and/or around the top of the hoof where it meets the hairline.

“Vesicular stomatitis also can affect mules, donkeys, cattle, bison, swine, sheep, goats, llamas and alpacas.”

Blisters and sores can make eating and drinking painful or difficult for animals.

Most infected animals recover within three weeks. A vaccine is not available, and no specific treatment is recommended other than supportive care such as rest, fluids and softened feeds.

The Texas Animal Health Commission updated the state’s vesicular stomatitis tally Wednesday, identifying 12 additional locations over the previous week. Ten of the premises are in Bastrop County and two in Williamson County.

All together, vesicular stomatitis has been confirmed in 11 Texas counties and 54 places since May 23. The counties are Bastrop, Falls, Guadalupe, Hidalgo, Jim Wells, Kinney, Nueces, San Patricio, Travis, Val Verde and Williamson.

Infected premises are quarantined and monitored. The locations are eligible for release from quarantine 21 days after all lesions have healed.

Vesicular stomatitis has struck eight Colorado counties: Adams, Boulder, Broomfield, Douglas, El Paso, Jefferson, Larimer and Weld. The National Veterinary Services Laboratory on July 17 confirmed the first positive tests involving four horses in Weld County.

Livestock events can go on as scheduled in Colorado, Dr. Roehr advised.

“Instead we are recommending that events and livestock owners take extra caution to control flies,” he said.

“Most of the cases we have investigated involve horses that have had no history of movement,” he added. “Therefore, controlling black flies and midges are very important in the prevention of the spread of disease.”

The Colorado State Veterinarian’s Office offered other advice for event organizers and livestock owners:

  • Avoid introducing feed equipment, cleaning tools and health care equipment from other herds.
  • Contact the destination state when moving livestock to ensure that all import requirements are met.
  • During an event, the sharing of water, feed and equipment should be minimized, and insect repellent should be applied daily, especially to an animal’s ears.

Vesicular stomatitis is zoonotic, meaning it can spread to people, although rarely. People infected with vesicular stomatitis display flu-like symptoms and sometimes lesions or blisters.

The disease should disappear over time because outbreaks are most common in the late summer and early fall in dry regions.

Livestock owners who think an animal may be infected with vesicular stomatitis should contact a veterinarian immediately, Davis said.

“If you’re dealing with a suspected case, communicate with your local veterinarian,” Davis said. “Your veterinarian will communicate with state health officials and determine the best course of action.”

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