Sign up now!
Don't show this again
Download the report!Continue to Site >
or wait 7 secs

Thank you for confirming your subscription!

(And remember, if ever you want to change your email preferences or unsubscribe, just click on the links at the bottom of any email.)

We’re glad you’re enjoying Pig Health Today.
Access is free but you’ll need to register to view more content.
Already registered? Sign In
Tap to download the app


Collect articles and features into your own report to read later, print or share with others

Create a New Report


Read Later

Create a new report

Report title (required) Brief description (optional)
follow us

You must be logged in to edit your profile.

Favorites Read Later My Reports PHT Special Reports
Pig Health Today is equipped with some amazing (and free) tools for organizing and sharing content, as well as creating your own magazines and special reports. To access them, please register today.
Sponsored by Zoetis

Pig Health Today | Sponsored by Zoetis


Processing fluids’ effectiveness in monitoring PCV2 in sow herds

Porcine circovirus type 2 (PCV2) is a hardy virus that, today, can be found throughout US pig production systems. It commonly impacts nursery and growing pigs, causing a failure to thrive, wasting and death. Co-infections are common and the clinical manifestation is known as porcine circovirus associated disease (PCVAD).

Vaccines have provided effective control options, but vertical transmission remains a challenge for some farms. Monitoring methods are limited and typically involve sampling placental umbilical cords, colostrum and serum from pre-suckling pigs, all of which are labor intensive and difficult to collect. As piglet processing fluids (PF) gain traction for other pathogens, it raises the question whether they would be an easy alternative for PCV2

With that in mind, Kayla Castevens, third-year veterinary student at North Carolina State University, set out to determine if PF could serve as a monitoring tool to establish sow vaccination protocols and whether parity influenced PCV2 detection.1

Sow farms enrolled

Seven sow farms were selected for the study and individually identified as Farm A through G. Here are the farm background details at the start of the study:

  • Farm A — A start-up farm; elevated downstream mortality, showing clinical signs of PCVAD, virus confirmed within associated lesions. Negative for porcine reproductive and respiratory syndrome virus (PRRSV) and porcine epidemic diarrhea virus (PEDV).
  • Farms B-G — Established farms; no PCVAD signs in downstream pig flows. Historically these herds were PRRS- and PEDV-positive but were currently stable and showed no signs of either disease. Farms increased biosecurity measures for piglet processing.

PCV2-vaccination protocols on the farms included:

  • All farms vaccinated piglets with a two-dose PCV2 vaccine at processing and weaning.
  • Farms B-G vaccinated gilts with a full-dose PCV2 vaccine at both 10 and 23 weeks of age.
  • Farm A vaccinated gilts with a single, full-dose PCV2 vaccine at 20 weeks of age. However, after PCVAD was confirmed, the farm added a full-dose PCV2 vaccine administered at 10 weeks of age.
  • None of the farms had a PCV2-vaccination protocol for sows.

PF collections and results  

Personnel at each of the farms began collecting tails and testicles from daily piglet processing, which were extracted and combined to submit one pooled sample per farm for the week. Castevens pointed out that a collection adjustment was made a month or so into the study for Farm A, due to PCVAD, and Farms B and C, due to intermittent PCV2 polymerase chain reaction (PCR)-positive test results. For those farms, samples were collected by individual litter for 5 days, for a total of 655 litter-specific samples.

The results shown in the accompanying table (Table 1), outline that for Farm A 100% of the samples tested positive, with Ct values less than 30. Farms B-G had varying results with 75% of the PCR-positive tests recording Ct values > 30 and 100% had a Ct  25.


Table 1. Weekly PCV testing of processing fluids

Click to enlarge.


When the samples were collected and pooled by day, Castevens found that Farm A tested positive for all 5 days, Farm B was PCV2-positive 4 of 5 days and Farm C tested positive 2 of 5 days. The daily samples were pooled for a weekly result for which Farms A and B tested positive and Farm C tested negative (Table 2).


Table 2. Pooled processing fluid PCV2 PCR results by day collected

Click to enlarge.


Castevens reviewed the pooled-PF results by sow parity (Table 3). Farm A, which was a start-up and only had parity 0 and parity 1 sows, recorded Ct values from 18.4 to 28.1. Those were notably lower than the Ct values for the positive test results for Farms B and C.

It is also noted that parity does not appear to be influential in viral shedding as the parity with PCR positive Ct values varies between farms.

Table 3. Pooled processing fluid PCV2 PCR Ct values by parity at each farm

Click to enlarge.


Take-home messages

The overall conclusions, according to Castevens, are that PF could be used as a monitoring tool for PCV2, that PCV2 viral shedding varies and parity is not influential.

“We need to go beyond just looking at positive or negative results,” she said, “and consider the degree of positivity.” Therefore, she proposed the following “Positivity Scale” to help determine the interventions needed, as shown here.

Ct < 25 = Intervention: Clinically relevant; there is likely active PCV2 infection; more diagnostics are needed; consider implementing a vaccination program.

Ct 25-30 = Alerted: Monitor the animals closely by increasing PCV2-testing frequency and checking downstream pig flows for developing PCVAD symptoms.

Ct > 30 = No Action: Not clinically significant.

She acknowledged that the Positivity Scale is a start but that it needs to be tested further and validated.

While her study supports the practice of using PF to detect PCV2, Castevens added that additional investigation is needed to determine the relationship to other monitoring methods, environmental contamination, co-morbidities, dilution factors from pooled samples and farrowing-house biosecurity to further validate PF as an accurate PCV2-monitoring option in sow herds.


1 Castevens K, et al. Use of processing fluids to monitor sows for porcine circovirus type 2 and determine parity influence on viral detection. Student Research, 50th Am Assoc of Swine Vet Annual Meeting. 2019;86.

Posted on September 11, 2019

tags: , , ,
  • Johnson: Five steps for porcine circovirus control

    Some breed-to-wean farms that have been vaccinated for porcine circovirus (PCV) have experienced breakdowns in their control of the virus. Clayton Johnson, DVM, outlines his top five steps for managing PCV outbreaks.

  • Processing fluids provide an option to monitor PCV2 and PCVAD

    Effective PCV2 control relies on vaccination of healthy pigs before they become infected. This goal cannot be accomplished in unstable herds whose sows give birth to viremic pigs.

  • Can the processing-fluid toolbox expand beyond PRRS?

    Piglet processing fluids have been shown to be a practical, time-efficient and affordable diagnostic tool for PRRS, and some indications suggest that PCV2 offers promise as well.

  • Comparing PCV2 gilt vaccination protocols and progeny status

    Porcine circovirus type 2 is the principal etiological agent of porcine circovirus associated disease (PCVAD), which can cost producers an estimated $3 to $4 per pig.

You must be logged in to edit your profile.

Share It
When a sow doesn’t reach her full potential, the cost to the farm and the income stream of the sow herd is often “grossly underestimated,” said John Deen, DVM, PhD, a professor at the University of Minnesota.

Click an icon to share this information with your industry contacts.
Google Translate is provided on this website as a reference tool. However, Poultry Health Today and its sponsor and affiliates do not guarantee in any way the accuracy of the translated content and are not responsible for any event resulting from the use of the translation provided by Google. By choosing a language other than English from the Google Translate menu, the user agrees to withhold all liability and/or damage that may occur to the user by depending on or using the translation by Google.