Ontario Animal Health Network (OAHN) Swine Network Quarterly Veterinary Report
H5N1 Highly Pathogenic Avian Influenza (HPAI) Updates
Dr. Tanya Rossi provided the network with an update on the evolving picture of HPAI both in Canada and internationally. (Information source: Dr. Murray Gilles, Animal Health Canada)
U.S.A:
Changes to the U.S.A administration have made it more difficult to gather information and scientific literature around the outbreak of HPAI in the U.S.A. An information freeze was put in place and has even affected Canadians with membership to the AABP as this freeze applies to collaboration with government agencies like the CDC and the USDA.
From the info available as of Jan 31, 2025, cases of HPAI in California are between 2-5 detections on avg per day. The USDA reports 34 cases in the last 30 days and all of them were reported from California.
On the US bulk milk sample surveillance map (see map below), all states except for California, Nevada, Texas and Michigan are listed as provisionally unaffected, and Mississippi remain unaffected with no clear explanation on how/why. Several states are still not participating in this surveillance initiative that was rolled out as mandatory in Dec 2024. Some of the states that aren’t participating are listed as provisionally unaffected. It is uncertain how this is the case when they aren’t conducting/reporting on national surveillance. The situation continues to be dynamic in the U.S. so for the most up to date reported information please visit this link.
HPAI U.S.A National Bulk Milk Surveillance Map- Feb 20, 2025
HPAI in poultry in the U.S.A is at its worst levels yet. USDA is reporting almost 18M birds affected with massive, multi-million bird flocks being affected including their second largest egg producer.
California reported its first detection of H5N9 in a duck farm that was also positive for H5N1.
The CDC is not reporting any new human cases, but the accuracy of this information is unknown. The U.S.A is reporting an increasing level of Flu in hospitals visits and test positives.
Canada:
Canada remains free of HPAI in cattle. The U.S. did confirm a detection of HPAI in swine, so this proves pigs are susceptible to this virus. Swine producers are encouraged to not feed milk or milk by-products to their pigs unless they have been previously pasteurized, as pasteurization kills Influenza virus.
Canada is experiencing a much less severe outbreak for HPAI in poultry. As of February 21, 2025, there are 30 infected premises for HPAI in poultry with 19 in BC, 1 AB, 8 ON, 1 QC, 1 NFLD.
International Reports:
The UK reported their first case of Avian Influenza in a human in years after a farm worker became infected.
Egypt reported detection of HPAI H5N2 clade 2.3.4.4b. The genomic characteristics of those viruses revealed mutations that could have important implications on animal and human health. Further surveillance and studies are needed to investigate its zoonotic potential and to better understand any associated risks.
Influenza A (IAV)- H3N2 clade 2010.1 detected for the first time in Quebec swine
Unfortunately, on Nov 19, 2024, RAIZO (the swine surveillance network in Quebec) released a statement that the first case of H3N2 clade 2010.1 Influenza was detected in a swine herd in Eastern Quebec. There have been no identified epidemiological links to Ontario with this detection. Quebec is the only other province to have detected H3N2 clade 2010.1 outside of Ontario to date. As of February 20, 2025, a total of 7 cases have been detected in Quebec, but they seem to be isolated to the same geographical area. Ontario first detected this clade in April 2022. All other provinces have been on the lookout for this virus since Ontario first detected it.
Porcine Epidemic Diarrhea (PEDV)/ Porcine Deltacoronavirus (PDCoV)
Jessica Fox from SHO provided an update on coronavirus cases in Ontario for Q4 of 2024. This quarter there were 4 new cases. Two cases in November (1 PED and 1 PDCoV), and two in December (1 PED, 1 PDCoV). November’s cases were both in farrow-to-wean farms, whereas December’s cases were in finishing barns.
The start of Q1 2025 has seen a significant increase in both PED and PDCoV cases. Producers need to stay vigilant with their biosecurity, as many of these cases are speculated to be linked to biosecurity breaches. Everyone in the swine industry in Ontario should to stay vigilant with biosecurity and to do your part to help prevent disease spread.
SHO continues to support elimination as the best strategy for disease control. Practitioners are encouraged to continue to be diligent in testing for coronaviruses in all gastrointestinal cases, as PDCoV can present with minimal clinical signs seen. Timely diagnosis of these cases can help limit widespread contamination and potential spread to other sites.
Practitioners are also encouraged to promote the use of SHARC by producers to stay aware of current positive sites in their proximity. Please refer any producers interested in enrollment to Jessica Fox Jessica.fox@swinehealthontario.ca. The PED and PDCoV Tracking map is available on the Swine Health Ontario website and shows current and annual cases by county. http://www.swinehealthontario.ca/Disease-Information/PED-PDCoV-Tracking-Map
OAHN Veterinary Clinical Impression Survey Veterinary Comments
Dr. Andrea Patterson provided an overview of the practitioner survey for Q4 2024, which had a very high level of participation with a total of 15 respondents.
There were some perceived increases in multi-systemic diseases by practitioners this quarter, namely erysipelas (20%), Strep and Glassers (20%), as well as PCV2 (20%). There were some additional comments provided by practitioners, reporting finishing outbreaks of erysipelas during Q4 of 2024. There was an additional comment describing a perceived increase in PCV2 type D prevalence in flows with concurrent viral pressure (specifically concurrent infections with PRRS and/or IAV).
An overall increase in respiratory disease was reported by practitioners this quarter, with 60% of responding vets perceiving an increase in PRRS (both breeding herds and growing herds), 67% perceiving an increase in Influenza A (IAV), and 33% perceiving an increase in Mycoplasma hyopneumoniae within Ontario herds. Multiple comments provided by practitioners specified an increase in IAV cases in finishing herds.
Some practitioners reported an increase in rotavirus infections this quarter (27%). 20% of survey respondents also reported an increase in PED/PDCoV cases; however, this is attributed to the dramatic increase in cases during Q1 of 2025 (which is when the survey is completed by practitioners). All participating practitioners reported the prevalence of ascarids in Ontario herds as stable, despite the increase reported by provincial slaughter reports.
Laboratory Diagnostic Reports
Animal Health Laboratory (AHL)
Dr. Josepha DeLay and Dr. Tim Pasma from Animal Health Lab provided an update on cases received by the lab during Q4 2024. A total of 1,328 swine cases were submitted to the AHL this quarter. Of these, 121 cases had a pathology component. A good or adequate clinical history was included for (96%) of this quarter’s pathology cases. Age group was included for 100% of cases, and the PID inclusion rate was 88%.
Cases and pathogens of interest during 2024 Q4 are as follows:
- There was an increase in detection (positive cases) of influenza A virus, PRRSV, and Mycoplasma hyopneumoniae in Q4 compared with Q3.
- A steady decline is noted over the past 3 years in PCV2-positive case numbers.
- Monophasic Salmonella Typhimurium was isolated more frequently in 2024 (42 cases) than in 2023 (22 cases) and 2022 (26 cases).
- Unusual necrohemorrhagic pneumonia cases were identified in a cluster of grower pigs from the same flow. Although gross and histologic lesions were compatible with a bacterial cause and were very suggestive of involvement of Actinobacillus pleuropneumoniae (APP) or A.suis, only Pasteurella multocida was isolated from lung, and in pure or mixed culture. A field strain of PRRSV was also detected in lung from this vaccinated herd. Whole genome sequencing (WGS) of the P.multocida isolate did not identify any potentially significant features, however the available database for this organism is minimal. Clinical signs and lesions in these pigs were attributed to concurrent infection with PRRSV and P. multocida, and bacterial culture results may have been influenced by recent herd-level antibiotic treatment. Monitoring is ongoing for any new similar cases in this or other herds.
Gallant Custom Laboratory (CEVA) Diagnostic Reports
Anna Pietruszkiewicz and Kevin Millsap reported on 2 cases submitted to Gallant Labs from Ontario in Q4 2024 in Ontario. These were both influenza (IAV) cases, and both were isolated as H3N2.
Ontario Slaughter Statistics
Federal Slaughter Statistic Summary (Q4 Aggregate)
Dr. Jordan Buchan provided the update that compared to last quarter (Q3 2024) there were 34,887 more hogs slaughtered and overall. There was in increase in trims categorized as “other”, as well as trims as a result of abcesses, in this quarter compared to Q3 of 2024. There was also an increase in condemnations because of enteritis, with a 5.9% increase over the last quarter, as well as a slight increase in erysipelas attributed condemnations (1.9% increase in Q4 vs Q3).
Provincial Slaughter Statistic Summary
During Q4 2024, there was a slight increase in number of condemns due to welfare concerns in December compared to the rest of the quarter. Data from both Q3 and Q4 of 2024 showed a significant increase in condemnations resulting from parasitic livers reached 3.21% (in October). This category made up the largest portion of condemnations in Q4 of 2024, followed by inflammatory conditions and abscesses, respectively.
CanSpotASF Surveillance Update
Dr. Tanya Rossi provided an update on the CanSpotASF surveillance submissions. Ontario samples submitted for CanSpotASF testing in 2024 Q4 included:
- Laboratory samples submitted by vets/pathologists: 27
- Provincial Abattoirs: 7
- Federal ON Abattoirs: 58
- Wild Pigs: 0
Dr. Rossi would like to remind practitioners to continue to send spleen samples in to AHL if you are sending tissues, even for respiratory case work-ups, in case it is eligible for CanSpotASF testing.
OAHN Project Update- Porcine Hemagglutinating and Encephalomyelitis Virus (PHEV)
Dr. Josepha DeLay provided an update on the porcine hemagglutinating and encephalomyelitis virus (PHEV) project, which is currently ongoing. This organism has been associated with respiratory disease in swine, specifically it has been identified in tracheobronchitis cases, so this project aims to understand its prevalence in lung and tracheal samples in Ontario swine. This project started in April of 2024 and is expected to conclude at the end of March 2025. As of February 6, 2025, 112 cases have been tested (lung +/- trachea samples), with a total of 9 cases testing positive on PHEV PCR. Stay tuned for a more comprehensive report pending the conclusion of this project. Of these cases, 5 were PCR positive, indicating low prevalence so far. Most of these positive cases have been in nursery or grow-finish pigs. These PCR-positive cases have been sent to Iowa State’s lab for further in situ hybridization to see virus localization in the lesion.
International Disease Topics Of Interest Summary
Dr. Al Scorgie reported on some interesting international and domestic disease surveillance reports and new research:
African Swine Fever (ASF)
U.S.A: Researchers at the University of Illinois have received a 3-year grant of US $650,000 from the USDA to develop a sensitive, rapid and low-cost, as well as portable biosensor to use for the on-farm detection and surveillance of ASF. The head of the project is Dr. Ying Fang, a pathobiologist with the College of Veterinary Medicine at the U. of Illinois. Dr. Fang is pairing with Brian Cunningham, the chair of Electrical and Computer Engineering. The engineering team will develop the biosensor. This team has previously developed nanotechnology to detect cancer and infectious diseases in humans. The research will work with detecting genes and proteins from ASF, not live ASF virus. Rapid detection on farm could allow containment and control measures to be put in place quickly. There have been rapid and portable detection devices developed in South Korea and Taiwan. (Pig Progress)
Germany: A wild boar that washed up in the Rhine River tested positive for ASF. The wild boar was found 60 kms northwest from the nearest ASF control zones. Authorities used drones and search dogs to search an area of 1,850 hectars surrounding where the boar was found bot no other wild boars were found. (Pig Progess, 02-12-2024)
Porcine Respiratory and Reproductive Syndrome (PRRS)
U.S.A: The SDRS reported that the PRRS positivity rate for sows in November was 19.58%, similar to October’s rate of 19.4%. The PRRS positivity rate for the wean-to-market pigs in November increased to 50.06% from 44.79% in October. In December, the positivity rate remained at 50%. The overall PRRS positivity rate was above 3 standard deviations in: IA, IN, OK and SD. Over 50% of the cases were PRRS 1-4-4 lineage L1c.5. This is the highest increase in the PRRS positivity rate since November 2018.
PRRS Persistence in Sows: Dr. Christine Mainquist-Whigham from DNA Genetics and Pillen Family Farms presented some interesting findings on a PRRS eradication project on the podcast, PRRS Persistent Infection Evaluation in 2 Sow Herds on Inside the Helix. There were two sow herds, a 600-sow commercial farm (site 1) and a 2,000-sow multiplier farm (site 2). The farms were infected by different strains of PRRSV. The farms did a traditional closure and live virus inoculation (LVI). At 20 weeks post-LVI, they bled and did tonsillar scrapings on all the sows and at multiplier they also bled and did tonsillar scrapings on the boars. They choose to do the testing at 20 weeks because that was when they would traditionally start to test herds to forecast time to PRRS stability. Almost all the serum samples were negative on PCR for PRRS. On tonsillar scrapings for site 1 they found that 3.5% of the sows were persistently infected and 1.8% of the sows were persistently infected at site 2. When they looked at the average age of the persistently infected sows versus sows that were not infected, the persistently infected sows averaged 21.8 weeks of age, (almost all positives were less than 30 weeks of age) and the negative cohort averaged 34.7 weeks of age. The other interesting finding was when they did tonsillar scrapings on the Meishan teaser boars, 18% were positive.
From these results Dr. Christine Mainquist-Whigham suggested that if you cannot have an off-site GDU and are loading the sow farm with gilts before doing a LVI, consider bringing in gilts that are over 16 weeks of age (to reduce the chance of having persistently infected sows) and consider culling all Meishan heat check boars. They recognize that doing tonsillar scrapings is not realistic on a commercial scale.
A side project was done with some of the persistently positive sows from site 2. These sows were moved off site and held for 3 weeks and resampled. PCR testing on tonsillar scrapings found that 20 out of 52 sows and Meishan boars had a lower CT value indicating more viral load. They did this project because they wanted to see if stress could possibly affect PRRS shedding. (Inside the Helix, E40, August 6, 2024)
Foot and Mouth Disease (FMD) Germany: On January 10th, 2025, Germany reported that FMD had been detected in a herd of water buffalo in Brandenburg. Ongoing testing in the surveillance has found no other positive cases so far. Testing at the National Reference Laboratory for Foot and Mouth Disease has shown that the FMDV found in the water buffalo was serotype 0. Closely related strains can be found in the Middle East and Asia. How FMDV entered Germany is unknown at this time.
Influenza
California: California has reported HPAI H5N9 and HPAI H5N1 in a commercial duck premise in Merced County. This is the first confirmed case of HPAI H5N9 in the USA. (CEZD Jan 20, 2025- Jan 28 2025)
Abortions
Drs. Emily Brouwer and Tim Pasma had an article on abortion in swine in a recent AHL, (Animal Health Laboratory) Newsletter. This is condensed version of that article. A high proportion of abortion cases submitted to AHL will have no specific diagnosis. From 2019 to 2023 the number of cases of abortion with no diagnosis ranged from a low 0f 25.9% to a high of 66.7%. Part of the reason no diagnosis is made is because there are non-infectious causes of abortion, and not all causes of abortion will cause gross or histological lesions.
Some of the non-infectious causes of abortion include seasonal effects, ambient temperatures such as heat stress, stress factors and toxic factors. Seasonal infertility occurs in late summer to early fall and is thought to be associated with photoperiod and high temperatures. Stress could be from comingling or movement. There could be maternal illness in the sows that results in abortion with no lesions in the fetus for example Influenza. Mycotoxins have been implicated in pregnancy failure in sows.
To improve the chances of finding a diagnostic cause of abortion, AHL recommends submitting up to three litters of aborted fetuses, include placentas and keeping fetuses chilled or frozen. (Dr. Emily Brouwer and Dr. Tim Pasma, AHL Newsletter 2024:28(3):12)
New World Screwworm (NWS): Cases of NWS have been reported for the first time in Southern Mexico. The first case was reported by Mexican authorities on November 22nd, 2024. This case was near the Guatemalan border. NWS are the larvae from the Cochliomyia hominivorax fly. The female fly lays eggs near open wounds. After the egg hatches the larvae burrow into living tissue to feed causing severe infections. Adult flies can travel a few miles but under ideal conditions may disperse further. Many Central American countries have been reporting cases of NWS. Panama had over 24,000 cases, Costa Rica over 13,000 and Nicaragua over 9,000. Over the past 2 years NWS has spread through Panama and into Costa Rica, Nicaragua, Honduras and Guatemala. The USDA announced a US$165 million emergency fund to protect US livestock from NWS. (SHIC Swine Disease Global Surveillance Report, Nov 5,2024-Dec 2, 2024)
How can you Participate in OAHN?
Look for the 2025 Q1 veterinary clinical impression survey that will come out the first week of April via an email through the OASV listserv.
If you are a practicing vet that sees swine in Ontario, please complete this survey when the email reminders are sent out through the OASV listserv.
