Circovirus Presents Unique Challenge

By now, I am confident that nearly everyone in the pork industry has read about, heard about, or unfortunately, had to deal with porcine circovirus Type 2 (PCV2)

By now, I am confident that nearly everyone in the pork industry has read about, heard about, or unfortunately, had to deal with porcine circovirus Type 2 (PCV2).

The virus continues to demand our attention and research dollars as we focus our efforts on thwarting the effects of this challenging foe. Like the “bad guy” in the movies, this opponent continues to rear its ugly head.

Case Study No. 1

I was called to visit the nursery of a 1,500-sow, farrow-to-finish, well-managed system. The farm practices three-site production with nursery rooms that are flowed all-in, all-out. The farm was negative for porcine reproductive and respiratory syndrome (PRRS).

The primary complaint in the nursery was elevated mortality/morbidity, and the fact that the producer failed to see any response to individual pig treatments. Mortality had risen from a typical 2.5% to over 7%.

On the first pass through the nursery rooms, pigs appeared active, thrifty and were “bouncing off the walls.” As we circled back through the pigs, however, it was apparent that some pigs were thumping, breathing open mouthed and gaunt. No diarrhea was noted.

Diagnostic submissions revealed that affected pigs were positive for PCV2. As these pigs entered the finisher, mortality rates and culls rose.

Unfortunately, our treatment protocols, which included individual pig injections and a variety of feed and water medications, proved futile.

On a positive note, we received a small amount of the conditionally released, two-dose circovirus vaccine. We vaccinated several weeks' worth of pigs at weaning, with a second dose administered two weeks later; the vaccinated pigs performed exceptionally well.

Surprisingly, when no circovirus vaccine was available, the pigs appeared to go through the system with no real health issues.

However, after eight months of non-vaccinated pigs going through the system, clinical signs of PCV2 reappeared in the nursery. The farm has reinstated the vaccination program.

Case Study No. 2

A finishing site consisting of four, 1,000-head barns showed elevated death loss in two of the four barns. The four barns were filled in two weeks, with pigs from the same source herd.

On my visit, the pigs were experiencing diarrhea, thumping, gauntness and wasting. Pigs were approximately 14 weeks of age. The producer had not seen a response to individual pig treatments or to water medications.

High levels of circovirus Type 2 were found in multiple tissues. Mortalities in the final closeouts were close to 30%. Pigs in two of the barns were not affected and had typical mortalities of 4-5%.

Working with the systems' nutritionist, an “intensive care diet” was developed for other units breaking with PCV2. The diet had a lower crude protein level, replaced with synthetic amino acids to enhance the immune system. Vitamins and trace minerals were also elevated.

Vitamin E and selenium along with aspirin and numerous antibiotics were utilized in water treatments.

Testimonials from the producers suggested improved stool consistency and less diarrhea using the “intensive care diet.” The system now uses cirovirus vaccine when available.

Case Study No. 3

A 300-sow, farrow-to-finish producer reported death losses up to 30% in late nursery and early finisher pigs. The facility, a single-site, continuous-flow system, had dealt with PRRS for the last several years. Control of PRRS was with sow and piglet vaccination.

Diagnostics from our investigation yielded PCV2. After several months of high mortality rates, the farm received commercial vaccine. Pigs vaccinated at weaning responded very well.


PCV2 can be an extremely challenging foe, and has created sleepless nights for many producers and their veterinarians. Conventional treatment therapies have been unsuccessful in our hands, although commercial vaccines appear to be very effective.

We all look forward to more answers in dealing with PCV2 as the scientific community works to learn more about this virus.

In the meantime, we follow the lessons we have learned with PRRS virus and implement good biosecurity and production management practices.

Please refer to the new guide, “A Producer's Guide To Managing PCVAD”, sponsored by the National Pork Board and the American Association of Swine Veterinarians. The brochure provides specifics on biosecurity, health and production guidelines for production systems and replacement stock. Free copies can be obtained by calling the Pork Checkoff Service Center at 800-456-7675 or by clicking on the Pork Store link on the home page.