EAST LANSING, Mich. — Five exhibition and one commercial herds in Iowa have been diagnosed with Seneca Valley virus (SVV), and at least two more states have reported outbreaks in the last five years.
Clinical symptoms of the disease in market or breeding animals include vesicular lesions on the snout and mouth area and lesions on the coronary band where hoof meets skin. These symptoms are shared with foot-and-mouth disease and vesicular stomatitis, both of which are considered by the USDA as Foreign Animal Diseases (FADs), and trigger an investigation.
While SVV is not considered an FAD, the symptom similarities require the disease to be reported to a state veterinarian’s office at this time. Dr. Chris Rademacher, in swine production medicine with Iowa State University extension, said, "The most significant sign of Seneca Valley disease is acute lameness in a high number of pigs."
In neonatal piglets, the herd will go from normal to epidemic mortality overnight, said Dr. Daniel Linhares, ISU professor in swine production medicine. "The mortality will return to whatever is normal for the farm in seven to 10 days," he said.
The virus was first identified during the 1980s. Recent outbreaks in Brazil spread quickly from farm to farm and mortality rates among 1- to 4-day-old piglets were as high as 80 percent, with most farms experiencing 30-50 percent mortality. Brazil, Canada and the United States each have identified slightly different strains of the same disease.
During the past five years, an unidentified group of diagnostic labs tested more than 1,000 oral fluid samples from hogs, resulting in numerous positive readings, according to Dr. Madonna Benjamin, DVM, MS, Michigan State University assistant professor and extension swine veterinarian.
"The American Assoc. of Swine Veter-inarians considers the virus as an emerging swine production disease," she said. "There is no known vaccine and we don’t know how it is spread. Although the production impacts at this time appear minimal, SVV can cause acute lameness."
An outbreak of the disease could cause disruptions in trade and pork product exports due to its similarities to significant FADs. Rademacher said, "It is important to stay vigilant and follow the call procedures to state veterinarians."
He added a serious FAD could easily be misdiagnosed as SVV. State pork boards are in the process of gathering information to help producers deal with any outbreaks that may occur. According to Benjamin, the following protocols should be followed in case of an outbreak:
•Do not move animals which are ill or exhibiting clinical signs, including clinically active lesions
•If possible, segregate/isolate affected animals on the site
•Document movements leading up to and immediately surrounding the onset of clinical signs, as this may be useful in disease analysis or the FAD investigation
•Cooperate with sample collection and submission as part of the FAD investigation under the direction of a state or federal animal health official
More guidelines are available at www.aasv.org/documents/FADReporting.pdf