Vesicular Stomatitis Continues Northward Drift

Worst Could be Over for Texas

Animal health officials say that the vesicular stomatitis (VS) outbreak in Texas appears to be winding down as of mid-August, but more than 150 infected animals have been detected in Texas, New Mexico, and Colorado, and more cases may be seen before the outbreak is complete. VS is a viral disease that appears every few years. Infected livestock, such as horses, cattle, goats, deer, swine, or other susceptible animals develop blisters, ulcers, or sloughing of the skin in and around the mouth, teats, or hooves. 
"This year Texas has two diseases that occur only sporadically--anthrax and VS," commented Bob Hillman, DVM, Texas' state veterinarian and head of the Texas Animal Health Commission (TAHC), the state's livestock and poultry health regulatory agency.
"Anthrax and VS are not related. Anthrax is a bacterial disease which is fatal to animals that become infected. However, outbreaks are usually localized. This year, we've had several confirmed cases of anthrax in Uvalde and Val Verde counties. Animals ingest the deadly bacteria when they graze where anthrax spores have become vegetative," Hillman explained. "VS is thought to be transmitted by sand flies and black flies, and while the viral infection causes lesions and temporarily debilitates an animal, it rarely causes death."
Hillman said eight premises in Texas currently are under VS quarantine, but no new cases have been confirmed since late July. VS-infected livestock and their herd mates are quarantined until at least 30 days after the last lesions are healed, a process that usually takes about two weeks. Restricted sites currently include a ranch in Dimmit County with equine animals; four in Starr County, two of which include cattle; an equine premises in Yoakum County; and two equine premises in Kerr County.
"We've released the quarantines on four premises since the outbreak began," noted Hillman. "The first released was in Reeves County, where the nation's initial VS case was confirmed in mid-May in a horse. Quarantines since have been lifted on one premises each in Val Verde, Starr, and Uvalde counties.
"When a VS outbreak occurs, it is not unusual for the disease to drift northward, as if it were being moved by a light breeze," commented John Romero, DVM, assistant state veterinarian for the New Mexico Livestock Board. "Right now, New Mexico has 80 VS-infected equine animals and one llama confined with their herd mates on 51 premises in 11 counties. No new cases have been confirmed recently in the southern part of the state."
New Mexico counties with quarantines include: Bernalillo, Eddy, Grant, Mora, Rio Aribba, San Miguel, Sandoval, Santa Fe, Socorro, Taos, and Valencia.
In Colorado, 52 premises with cattle and/or equids in 13 counties are under VS quarantine. Counties involved include Adams, Alamosa, Boulder, Douglas, El Paso, Fremont, Huerfano, Larimer, Las Animas, Otero, Park, Pueblo, and Weld.
"The number of cases will slow when weather cools, sometime in early October," noted Keith Roehr, DVM, assistant state veterinarian with the Colorado Department of Agriculture's Division of Animal Industry. Roehr explained that the VS outbreak will not end until sometime in early November, when consistent freezes will kill the flies thought to transmit the disease.
"Livestock owners in Texas, New Mexico and Colorado call the state of destination prior to shipping animals, to ensure that animals meet all entry requirements," Hillman urged. "Some states have imposed permitting, testing or quarantine restrictions to protect against the spread of VS. Call before you haul to avoid complications later."
Livestock owners should report potential cases of VS to their respective state veterinarians' office, so tests may be run to correctly diagnose the illness, and to rule out an accidental or intentional introduction of foot-and-mouth disease (FMD), a highly dangerous foreign animal disease that can affect cattle, sheep and other cloven-hooved animals.
To make a report, owners and private veterinary practitioners should call:

  • Texas Animal Health Commission 800/550-8242
  • New Mexico Livestock Board 505/841-6161
  • Colorado Department of Agriculture, state veterinarian's office 303/239-4161
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