What is Vesicular Stomatitis and Why Do I Care?

This viral disease, that has been present in California for several months, isn’t the end of the world for the dairies, but it could certainly cause some headache.

What is Vesicular Stomatitis?

Vesicular Stomatitis is a viral infection caused by Vesicular Stomatitis Virus (VSV) that can cause disease in a wide variety of livestock species, but most commonly affects horses and cattle. The virus can be transmitted by direct contact from animal-to-animal, via contaminated equipment, and by biting insect vectors. There is no vaccine available to prevent infection and no specific treatment.

How bad is the disease?

Only rarely does infection result in animal death, but blisters and ulcers on the mouth, teats and feet can cause dramatic reduction in production. Animals typically recover fully within two weeks with supportive care. The disease in ruminants can be indistinguishable from Foot and Mouth Disease (FMD), which is why VSV is a reportable disease requiring regulatory control and investigation.

What kind of farms are involved?

Since May of last year, 316 premises have been affected in nineteen California counties. The vast majority of those premises were horse facilities; only nine of them were cattle operations. Cattle infections have been identified in Fresno, San Diego, Santa Barbara and Mariposa Counties.

Is the disease still spreading?

With the new year new cases were being reported far less frequently. This is likely due to the combination of cooler weather with fewer flies, enhanced industry awareness and movement controls by CDFA. All previously infected farms have been released from quarantine, with two Sacramento equine facilities cleared on January 18th. We are currently awaiting completion of a 30-day monitoring period after which both California and the U.S. can be designated as “VSV Free”. CDFA has a dedicated webpage that provides weekly status updates and the most current USDA VSV Situation Reports.

Has the current VSV outbreak affected the dairy industry?

Fortunately to date there has only been one dairy that has tested positive for VSV. The affected premises was able to effectively manage and isolate the affected animal on site, restricting it to a singular case. Some animal shipments may have been disrupted during this period, since animals coming from affected states or returning to California require a Certificate of Veterinary Inspection. The CVI must state that the animals are free of signs of VSV and have not been exposed to the virus or have been on an affected premise during the last seven days. Cattle are

ineligible to be shipped to Canada until California has been declared free of VSV for at least 21-days.

What about this summer’s fair and show season?

Depending on how long the state’s outbreak persists, there may be certain restrictions or requirements for shows and fairs this spring and summer. Producers can coordinate with their veterinarian in advance to ensure that any testing or health certificate requirements are satisfied.

What happens to dairy that is identified as VSV positive?

All animal movement involving a quarantined VSV-positive dairy would be restricted, complicating movement of calves to and from heifer raising facilities. Feed deliveries and milk shipments would also require permits for movement and would be managed through CDFA. The agency has also made provisions for deadstock to be removed to rendering and cull cows to go to slaughter under permit. Quarantine remains in effect for two weeks from the discovery of the most recent animal’s infection.

What can I do to protect my dairy?

Given the cold weather and decreased vector activity, VSV detections have significantly decreased, but preventative measures should still be strongly considered on dairy facilities, including:

· Start planning now to minimize fly habitat for this coming spring. A good place to start is the Dairy Fly Control and Your Bottom Line, a primer co-produced by CDQAP and UC Riverside’s Department of Entomology.

· Work with your veterinarian to implement biosecurity protocols to limit contact between healthy and potentially infected animals. This would include replacements, animals returning from fairs and shows and cows with fence-line contact with beef animals. ☐ Train and empower dairy employees to report signs of the disease, such as blisters, sores, or lameness. This poster in English and Spanish can be useful.

· If signs do appear, isolate and quarantine suspected cases immediately and arrange for a timely veterinary consultation.

· To prevent not only VSV but also other disease entry (Tuberculosis, contagious mastitis, hairy foot warts) review your dairy’s biosecurity plan with your veterinarian. A good place to start is the NMPF’s Everyday Biosecurity manual for dairies.