A feral pig in Central Oregon has tested positive for a contagious viral disease that can spread to livestock and wildlife, causing neurological, respiratory and reproductive disorders.
The disease, called pseudorabies, is found predominately in swine, though other mammals including cattle, sheep, goats, cats, dogs, coyotes, bears and deer are also susceptible.
It does not affect humans.
Ryan Scholz, district veterinarian for the Oregon Department of Agriculture, said the adult female pig was sampled June 8 for pseudorabies as part of the state’s ongoing feral swine control and disease surveillance program, overseen by USDA Wildlife Services.
Not only can feral pigs transmit diseases, but they cause millions of dollars in agricultural, environmental and property damage through destructive rooting and grubbing activities that degrade natural habitats and encourage the spread of noxious weeds.
Since the surveillance program was implemented in 2007, Oregon has gone from as many as 5,000 feral pigs 20 years ago to an estimated 200 today. Scholz said there is only one known population of feral pigs remaining in the state in rural Wheeler County.
USDA Wildlife Services did not provide any other information about where the infected pig was found. This is the first ever case of pseudorabies in Oregon.
“While the presence of (pseudorabies) in Oregon has so far been an isolated event, it shows that our disease surveillance program is working,” Scholz said. “It is too early to know how this disease appeared in Oregon, but additonal testing and investigation is ongoing.”
Pseudorabies, also known as Aujeszky’s Disease, is not actually related to rabies. Rather, it is a member of the herpes family of viruses. However, symptoms affecting the central nervous system of animals may resemble rabies, such as abnormal gait, intense scratching, self-mutilation or convulsions, hence the name.
Pigs are the only known natural hosts for pseudorabies. The virus is usually transmitted by direct contact, though it can spread indirectly by drinking contaminated water or inhaling tiny airborne droplets — similar to transmission of COVID-19.
According to the California Department of Food and Agriculture, aerosol particles containing pseudorabies can travel up to 20 yards in ideal conditions.
Scholz encouraged ranchers to be aware if they live in an area with feral pigs, and take appropriate steps to keep their livestock separate from wildlife.
“If you live in an area where there are feral pigs, you could be at risk,” Scholz said. “An ounce of prevention really does go a long way.”
Feral pigs are prohibited in Oregon. They are considered a predatory animal on private land, and a non-game, non-protected animal by the Oregon Department of Fish and Wildlife on public land. They are omnivores, and will eat just about anything from leaves and grasses to crops and other small animals.
In 2009, the Oregon Legislature passed a bill requiring landowners and land managers to notify ODFW within 10 days of finding feral pigs on their property. Then they have 60 days to submit a feral swine removal plan to the agency.
ODFW spokeswoman Michelle Dennehy said there is no evidence of pseudorabies infecting any other wildlife in Oregon, and veterinary staff do not anticipate any impacts “due to the low chance of contact occurring between wildlife and feral swine in the state.”
Scholz, with ODA, said this particular strain of pseudorabies primarily affects pigs, with just limited infections in other livestock species. He said there are not many domesticated pigs in that area of Central Oregon, making livestock transmission unlikely.
“With this strain, it’s not anything we would worry too much about anyway,” Scholz said.
The disease was eradicated from the commercial hog industry in 2004. Oregon’s pork production is valued at approximately $2.56 million, according to stats from the industry’s checkoff program. By comparison, Iowa is the top pork producing state at $5.6 billion.