It’s been about a decade since the Mystery Swine Disease moved on to become what the industry now knows as porcine reproductive and respiratory syndrome. While veterinarians, producers, researchers and the like have all made progress in shifting through what does and does not work in preventing, treating and controlling PRRS, it remains an elusive challenge.

Many PRRS-infected herds today are subclinical. “There are many highly productive herds with PRRS,” notes Pat Halbur, Iowa State University veterinary pathologist.

He says that those herds tend to have low-virulent strains of PRRS virus. But diligent management also plays a key role. In such cases, the herd veterinarian and the producer or production manager does a good job of controlling other diseases, maintain excellent pig flow and minimizes environmental stresses.

However, PRRS starts costing a producer a lot of money when the unit faces pig-flow constraints, there’s a highly virulent virus strain in the herd, environmental conditions are less than optimum, or the producer and veterinarian fail to take a whole-herd system management approach. “You control PRRS in the nursery and finisher by controlling it in the sow herd,” says Halbur.

While a herd can remain productive in spite of PRRS, the cost of an outbreak can be devastating, says Scott Dee, University of Minnesota veterinarian and PRRS expert. He points to studies that have shown a $228-per-sow loss over a one-year period due to PRRS. The culprits were: elevated mortality rates, reduced growth and excessive medication and vaccination costs associated with PRRS.

“Independent research conducted for the Pipestone Veterinary Clinic (in Pipestone, Minn.) placed a $1-million price tag on a sow herd producing 1,200 pigs per week suffering from a PRRS outbreak,” notes Gordon Spronk, veterinarian with the clinic. “Those herds can continue to see effects of the disease for up to eight months or two entire turns of the barn.”