Canine Parvovirus Detected in South Dakota Swine Herds
No evidence of clinical disease resulting from viral spillover.
In 2020, diagnostic testing showed nine swine lung samples were positive for canine parvovirus type 2 (CPV-2). The positive samples were among 90 being analyzed at the South Dakota State University Diagnostic Laboratory in Brookings, South Dakota.
“When we saw the positive samples, it caught my attention because canine parvovirus is clinically important in dogs, but it had not previously been identified in pigs,” explained Ben Hause, Ph.D., chief scientific officer at Cambridge Technologies in Worthington, Minnesota. At the time, Hause was part of the diagnostic faculty at South Dakota State University analyzing the samples.
“We found this by accident in samples that came into our lab for unrelated diagnostic testing,” he said. “There’s no evidence this virus is having a clinical effect on pigs.”
One of the reasons the positive samples were of such interest to researchers was the history of CPV-2. Identified in 1978, the disease in dogs was thought to have originated from a spillover of a feline panleukopenia-like virus. CPV-2 caused a worldwide pandemic in dogs.
Today, canine parvovirus is known to be highly contagious and can have severe effects, especially in young dogs. The American Veterinary Medical Association (AVMA) notes that most
deaths in dogs can occur as quickly as 48 to 72 hours following the onset of clinical signs like severe diarrhea.
“That same virus spilled over to wildlife – like coyotes, skunks and pangolins. When it spills over, it can cause disease,” Hause noted. “When we find it in pigs, it’s reasonable to ask ‘could this be the start of something?’ Our results do not support a role for CPV-2 in causing disease in pigs.”
Identification in swine herds
Hause and his team analyzed samples collected between September and November 2020 from swine farms within 150 miles of Brookings, South Dakota Of the nine positive samples, two matched CPV-2 found in a coyote identified in Montana in 2012 – leading the team to believe the source of infection is coyote feces.
The research team then collected an additional 20 samples from sows on a single South Dakota farm. Of the 20 samples, 13 (65%) were weakly positive for antibodies that recognized CPV-2. Other farms within the state were sampled, and 92% were positive for low-titered CPV-2 antibodies. It suggests widespread CPV-2 exposure in South Dakota herds.
“These results showed that canine parvovirus did get into these pigs, and it looked like they were infected – but it was not a real robust infection,” Hause said. “An additional study tried to infect pigs with CPV-2, but nothing happened. This is an example of something that viruses do – spilling into other species. Just because we find them in an unusual host doesn’t mean they are causing disease.”
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