U.S. Department of Agriculture researchers are working to solve a swine disease that has a major negative effect on the pork industry. USDA scientist Dr. Joan Lunney says Porcine Reproductive and Respiratory Syndrome, or PRRS (pronounced “purrs”), costs U.S. pork producers money and pigs every year.

“Overall, in the United States, PRRS costs us 642-million (dollars) a year and if you take into account veterinary costs, it’s one billion a year in the U.S. alone,” Lunney says.

For young pigs, being sick means respiratory problems and loss of growth, so it’s a major issue in terms of production. “In the adult sow, if she gets PRRS when she’s pregnant, she can lose her litter, and/or her litter becomes sick and some pigs die in utero or are very unthrifty when they’re born,” Lunney says.

To alleviate this situation, Lunney and her colleagues in Beltsville, Maryland — just outside of Washington D.C. — have discovered a genetic marker that shows which pigs are resistant to the effects of PRRS. “We’ve been able to show that there is a region on swine chromosome four that is associated with decreased viral levels and increased growth,” Lunney says. “So, this is really important because it means that we can help farmers now to decrease the effect of PRRS in their herds.”

With this knowledge, producers and animal breeders could introduce PRRS tolerant swine into their herds thereby reducing the effects of the virus. “They would be buying pigs that are resistant, but not completely resistant to PRRS,” Lunney says. “This is not a situation where we have zero PRRS. It is a 15-percent decrease in PRRS and an 11-percent increase in growth traits.”

The researchers are now trying to find the exact gene that leads to PRRS tolerance in hopes of developing a vaccine and treatment.

Iowa is the nation’s top pork producing state, with approximately 30 million hogs raised in Iowa each year.