Porcine Reproductive/Respiratory Syndrome (PRRS)

Disease Basics

Porcine Reproductive/Respiratory Syndrome (PRRS) is of major economic importance in the United States and the world.  The cost of the disease in the United States alone is estimated to be over 600 million dollars annually.  It is a viral infection that can manifest as lowered farrowing rates, a marked increase in abortions, stillborn, mummified and weak live born piglets and deaths.  There is also a respiratory disease, which can be severe, particularly when other agents are present and can result in high death rates in suckling and weaned pigs.  In some herds, though, the infection will show no symptoms.    


Biosecurity is the primary method for preventing PRRS from entering a herd.  Some of the most common biosecurity strategies are:

  • Quarantine and testing of incoming breeding stock
  • Use semen from non-PRRS hogs for breeding
  • Proper sanitation of transport vehicles
  • Disinfection of boots and equipment

Clinical ​​Signs of Illness

The clinical signs of PRRS vary with the strain of virus and the age of the animal.  Often the disease doesn’t produce symptoms. In adults, the common signs are reduced appetite, fever, premature farrowing and abortion, loss of balance, circling, falling to one side and death.  In affected litters, you may see an increase in stillborn pigs, high pre-weaning mortality, mummified pigs, weak-born pigs and runny eyes.  In weaned pigs, loss of appetite and lethargy, failure to thrive, difficulty breathing and blotchy reddening of the skin are signs of infection.  


Diagnosis of PRRS requires sample submissions to a diagnostic laboratory.  Swine owners should contact their veterinarian for assistance.  

Hu​man Health

There is no record of PRRS causing human disease.