Texas animal health officials say sand flies and black flies likely play a role in the spread of the virus. Controlling insects around livestock is important to horse and herd health.

Due to an increasing number of confirmed Vesicular Stomatitis cases in Texas, Louisiana Department of Agriculture and Forestry animal health officials are imposing enhanced requirements effective immediately on livestock entering Louisiana from a state that has diagnosed cases of VS.

According to a statement issued by Louisiana animal health officials on June 26:  "Any livestock (equine, bovine, porcine, caprine, or ovine) entering Louisiana from a county where VS has been diagnosed within the last thirty (30) days must be accompanied by a Certificate of Veterinary Inspection written within ten (10) days of entry containing the following statement: All animals identified on this certificate have been examined and found free from signs of VS, have not been exposed to VS, and have not originated from a premises which is under quarantine for VS."

As a result of the VS cases reported in Texas since late May, similar limitations have already been imposed by California, Florida, Idaho, Illinois, Kentucky, Michigan, Montana, Nebraska, New York, North Carolina, North Dakota, Oklahoma, South Carolina, and Vermont.

Also, international limitations on the movement of Texas livestock are in place. Limited movement restrictions have been enacted by Canada, the European Union, Russia, and South Korea. A complete list of state and international restrictions is available from the USDA Veterinary Services' (VS) Austin office at 512-383-2411.

In the past decade the Southwestern and Western United States have experienced a number of VS outbreaks. Outbreaks usually occur during the warmer months, often along waterways. As a result, certain species of wildlife including cervids such as whitetail deer and mule deer, as well as feral pigs can contract and spread the disease.