Etiology of acute respiratory disease in fattening pigs in Finland

Serotyping and antimicrobial resistance of Actinobacillus pleuropneumoniae isolates from fattening pigs in Poland from 2019 to 2024

BACKGROUND

Actinobacillus pleuropneumoniae is a prevalent respiratory pathogen causing substantial economic losses in swine production worldwide. The bacterium's ability to rapidly develop antimicrobial resistance (AMR) poses a significant challenge to effective treatment and control. In Poland, limited data on A. pleuropneumoniae serotype distribution and AMR patterns hinder evidence-based treatment strategies. This study examined the serotype diversity and AMR patterns of A. pleuropneumoniae isolates from porcine pleuropneumonia outbreaks in northeastern Poland between 2019 and 2024, providing crucial information for regional veterinary practices and antimicrobial stewardship efforts.

RESULTS

Analysis of 119 isolates from 67 farms demonstrated the predominance of serotype 2 (65.5%), followed by serogroups 3, 6, 8 (18.5%) and 1, 9, 11 (15.1%). This distribution differs from recent trends in other European countries, suggesting regional epidemiological variations. High resistance rates were observed for tylosin (55.5%), gentamicin (36.1%), doxycycline (32.8%), and sulfamethoxazole/trimethoprim (26.1%). Multidrug resistance fluctuated between 14.3% and 21.9% over the study period, with no clear linear trend. From 2022 onwards, strains exhibiting resistance to seven or more antimicrobials, including cephalosporins, emerged, marking a significant shift in resistance profiles. Temporal analysis revealed diverse resistance patterns, with significant increases in some antimicrobials (e.g., sulfamethoxazole/trimethoprim, p = 0.001) and stability in others (e.g., tetracycline, p = 0.890). Notably, several antimicrobials, including florfenicol and colistin, maintained 100% efficacy against all isolates throughout the study period.

CONCLUSIONS

The findings highlight the dynamic nature of AMR development in A. pleuropneumoniae and underscore the need for ongoing surveillance in the region. The emergence of highly resistant strains, particularly those resistant to cephalosporins, raises concerns about future treatment options. These results can guide evidence-based treatment strategies and enhance antimicrobial stewardship efforts in regional swine production. Furthermore, the study emphasizes the importance of local AMR data in guiding antimicrobial use policies and the need for a coordinated approach to combat AMR in veterinary medicine.

RGB-based machine vision for enhanced pig disease symptoms monitoring and health management: a review

The growing demands of sustainable, efficient, and welfare-conscious pig husbandry have necessitated the adoption of advanced technologies. Among these, RGB imaging and machine vision technology may offer a promising solution for early disease detection and proactive disease management in advanced pig husbandry practices. This review explores innovative applications for monitoring disease symptoms by assessing features that directly or indirectly indicate disease risk, as well as for tracking body weight and overall health. Machine vision and image processing algorithms enable for the real-time detection of subtle changes in pig appearance and behavior that may signify potential health issues. Key indicators include skin lesions, inflammation, ocular and nasal discharge, and deviations in posture and gait, each of which can be detected non-invasively using RGB cameras. Moreover, when integrated with thermal imaging, RGB systems can detect fever, a reliable indicator of infection, while behavioral monitoring systems can track abnormal posture, reduced activity, and altered feeding and drinking habits, which are often precursors to illness. The technology also facilitates the analysis of respiratory symptoms, such as coughing or sneezing (enabling early identification of respiratory diseases, one of the most significant challenges in pig farming), and the assessment of fecal consistency and color (providing valuable insights into digestive health). Early detection of disease or poor health supports proactive interventions, reducing mortality and improving treatment outcomes. Beyond direct symptom monitoring, RGB imaging and machine vision can indirectly assess disease risk by monitoring body weight, feeding behavior, and environmental factors such as overcrowding and temperature. However, further research is needed to refine the accuracy and robustness of algorithms in diverse farming environments. Ultimately, integrating RGB-based machine vision into existing farm management systems could provide continuous, automated surveillance, generating real-time alerts and actionable insights; these can support data-driven disease prevention strategies, reducing the need for mass medication and the development of antimicrobial resistance.

Influenza A Viruses in the Swine Population: Ecology and Geographical Distribution

Despite the efforts of practical medicine and virology, influenza viruses remain the most important pathogens affecting human and animal health. Swine are exposed to infection with all types of influenza A, B, C, and D viruses. Influenza viruses have low pathogenicity for swine, but in the case of co-infection with other pathogens, the outcome can be much more serious, even fatal. Having a high zoonotic potential, swine play an important role in the ecology and spread of influenza to humans. In this study, we review the state of the scientific literature on the zoonotic spread of swine influenza A viruses among humans, their circulation in swine populations worldwide, reverse zoonosis from humans to swine, and their role in interspecies transmission. The analysis covers a long period to trace the ecology and evolutionary history of influenza A viruses in swine. The following databases were used to search the literature: Scopus, Web of Science, Google Scholar, and PubMed. In this review, 314 papers are considered: n = 107 from Asia, n = 93 from the U.S., n = 86 from Europe, n = 20 from Africa, and n = 8 from Australia. According to the date of publication, they are conditionally divided into three groups: contemporary, released from 2011 to the present (n = 121); 2000-2010 (n = 108); and 1919-1999 (n = 85).

Development of a Triplex qPCR Assay Based on the TaqMan Probe for the Detection of Haemophilus parasuis, Streptococcus suis Serotype 2 and Pasteurella multocida

Porcine respiratory disease is a significant economic problem for the global swine industry. Haemophilus parasuis (H. parasuis), Streptococcus suis (S. suis), and Pasteurella multocida (P. multocida) are three important pathogenic bacteria of the swine respiratory tract. Notably, the three pathogens not only frequently manifest as mixed infections, but their striking clinical similarities also present difficulties for pig populations in terms of disease prevention and treatment. Thus, we developed a triplex real-time quantitative polymerase chain reaction (qPCR) assay based on a TaqMan probe for the detection of H. parasuis, S. suis serotype 2, and P. multocida. Primers and probes were designed to target the conserved regions of the H. parasuis OmpP2 gene, the S. suis serotype 2 gdh gene, and the P. multocida Kmt1 gene. By optimizing the reaction system and conditions, a triplex qPCR method for simultaneous detection of H. parasuis, S. suis serotype 2, and P. multocida was successfully established. The amplification efficiencies of the standard curves for all three pathogens were found to be highly similar, with values of 102.105% for H. parasuis, 105.297% for S. suis serotype 2, and 104.829% for P. multocida, and all R2 values achieving 0.999. The specificity analysis results showed that the triplex qPCR method had a strong specificity. The sensitivity test results indicated that the limit of detection can reach 50 copies/μL for all three pathogens. Both intra- and inter-assay coefficients of variation for repeatability were below 1%. This triplex qPCR method was shown to have good specificity, sensitivity, and reproducibility. Finally, the triplex qPCR method established in this study was compared with the nested PCR as recommended by the Chinese national standard (GB/T34750-2017) for H. parasuis, the PCR as recommended by the Chinese national standard (GB/T 19915.9-2005) for S. suis serotype 2, and the PCR as recommended by the Chinese agricultural industry standard (NY/T 564-2016) for P. multocida by detecting the same clinical samples. Both methods are reasonably consistent, while the triplex qPCR assay was more sensitive. In summary, triplex qPCR serves not only as a rapid and accurate detection and early prevention method for these pathogens but also constitutes a robust tool for microbial quality control in specific pathogen-free pigs.

The economic impact of endemic respiratory disease in pigs and related interventions - a systematic review

BACKGROUND

Understanding the financial consequences of endemically prevalent pathogens within the porcine respiratory disease complex (PRDC) and the effects of interventions assists decision-making regarding disease prevention and control. The aim of this systematic review was to identify what economic studies have been carried out on infectious endemic respiratory disease in pigs, what methods are being used, and, when feasible, to identify the economic impacts of PRDC pathogens and the costs and benefits of interventions.

RESULTS

By following the PRISMA method, a total of 58 studies were deemed eligible for the purpose of this systematic review. Twenty-six studies used data derived from European countries, 18 from the US, 6 from Asia, 4 from Oceania, and 4 from other countries, i.e., Canada, Mexico, and Brazil. Main findings from selected publications were: (1) The studies mainly considered endemic scenarios on commercial fattening farms; (2) The porcine reproductive and respiratory syndrome virus was by far the most studied pathogen, followed by Mycoplasma hyopneumoniae, but the absence or presence of other endemic respiratory pathogens was often not verified or accounted for; (3) Most studies calculated the economic impact using primary production data, whereas twelve studies modelled the impact using secondary data only; (4) Seven different economic methods were applied across studies; (5) A large variation exists in the cost and revenue components considered in calculations, with feed costs and reduced carcass value included the most often; (6) The reported median economic impact of one or several co-existing respiratory pathogen(s) ranged from €1.70 to €8.90 per nursery pig, €2.30 to €15.35 per fattening pig, and €100 to €323 per sow per year; and (7) Vaccination was the most studied intervention, and the outcomes of all but three intervention-focused studies were neutral or positive.

CONCLUSION

The outcomes and discussion from this systematic review provide insight into the studies, their methods, the advantages and limitations of the existing research, and the reported impacts from the endemic respiratory disease complex for pig production systems worldwide. Future research should improve the consistency and comparability of economic assessments by ensuring the inclusion of high impact cost and revenue components and expressing results similarly.

Artificial Intelligence for Automatic Monitoring of Respiratory Health Conditions in Smart Swine Farming

Porcine respiratory disease complex is an economically important disease in the swine industry. Early detection of the disease is crucial for immediate response to the disease at the farm level to prevent and minimize the potential damage that it may cause. In this paper, recent studies on the application of artificial intelligence (AI) in the early detection and monitoring of respiratory disease in swine have been reviewed. Most of the studies used coughing sounds as a feature of respiratory disease. The performance of different models and the methodologies used for cough recognition using AI were reviewed and compared. An AI technology available in the market was also reviewed. The device uses audio technology that can monitor and evaluate the herd's respiratory health status through cough-sound recognition and quantification. The device also has temperature and humidity sensors to monitor environmental conditions. It has an alarm system based on variations in coughing patterns and abrupt temperature changes. However, some limitations of the existing technology were identified. Substantial effort must be exerted to surmount the limitations to have a smarter AI technology for monitoring respiratory health status in swine.

Diversity of respiratory viruses present in nasal swabs under influenza suspicion in respiratory disease cases of weaned pigs

Respiratory diseases in weaned pigs are a common problem, with a complex etiology involving both viruses and bacteria. In the present study, we investigated the presence of eleven viruses in nasal swabs, collected from nurseries (55 cases) under the suspicion of swine influenza A virus (swIAV) and submitted by swine veterinarians for diagnosis. The other ten viruses included in the study were influenza B (IBV) and D (IDV), Porcine reproductive and respiratory syndrome virus (PRRSV), Porcine respiratory coronavirus (PRCV), Porcine cytomegalovirus (PCMV), Porcine circovirus 2 (PCV2), 3 (PCV3) and 4 (PCV), Porcine parainfluenza 1 (PPIV1) and Swine orthopneumovirus (SOV). Twenty-six swIAV-positive cases and twenty-nine cases of swIAV-negative respiratory disease were primarily established. While IBV, IDV, PCV4 and PPIV1 were not found in any of the cases, PRCV, SOV, and PCMV were more likely to be found in swIAV-positive nurseries with respiratory disease (p < 0.05). Overall, PCV3, PRRSV, and PCMV were the most frequently detected agents at herd level. Taken individually, virus prevalence was: swIAV, 48.6%; PRCV, 48.0%; PRRSV, 31.6%; SOV, 33.8%; PCMV, 48.3%, PCV2, 36.0%; and PCV3, 33.0%. Moreover, low Ct values (<30) were common for all agents, except PCV2 and PCV3. When the correlation between pathogens was individually examined, the presence of PRRSV was negatively correlated with swIAV and PRCV, while was positively associated to PCMV (p < 0.05). Also, PRCV and SOV were positively correlated between them and negatively with PCMV. Besides, the analysis of suckling pig samples, collected in subclinically infected farrowing units under an influenza monitoring program, showed that circulation of PRCV, PCMV, SOV, and PCV3 started during the early weeks of life. Interestingly, in those subclinically infected units, none of the pathogens was found to be correlated to any other. Overall, our data may contribute to a better understanding of the complex etiology and epidemiology of respiratory diseases in weaners. This is the first report of SOV in Spain and shows, for the first time, the dynamics of this pathogen in swine farms.

The role of co-infections in M. hyopneumoniae outbreaks among heavy fattening pigs: a field study

Little is known about how co-infections and genotype dynamics affect Mycoplasma hyopneumoniae infection in fattening pigs. This study was aimed at assessing the role of co-infections in M. hyopneumoniae outbreaks, their influence on the presence of M. hyopneumoniae genotypes and their impact on consequent lung lesions. Tracheobronchial swabs (TBS) from 300 finishers were collected from 10 farms at the onset of enzootic pneumonia outbreaks and 1 month later, sampling of 3 groups per farm: Group A showed clinical signs first, Group B was housed near Group A, and Group C was located in a different building. Pigs’ lungs were scored at the slaughterhouse. TBS were tested for the main pathogens involved in respiratory diseases, and samples positive for M. hyopneumoniae were genotyped by multiple-locus variable-number tandem repeat analysis (MLVA). Pigs in Group A showed the highest prevalence and load of M. hyopneumoniae. A positive association was detected between M. hyopneumoniae and Mycoplasma hyorhinis, whereas Actinobacillus pleuropneumoniae was more frequent when the M. hyopneumoniae load was higher. Nevertheless, co-infection had no effect on lung lesion scores. The presence of multiple MLVA types (mixed infections) increased in time only in pigs from Group C and was positively associated with porcine reproductive and respiratory syndrome virus infection. Lung lesions were more severe in pigs with at least one TBS positive for M. hyopneumoniae and in pigs with a history of mixed infections. The central role of M. hyopneumoniae and relevance of mixed infections suggest that increased biosecurity might be beneficial for lung lesion sequelae.

Histopathologic patterns and etiologic diagnosis of porcine respiratory disease complex in Brazil

ABSTRACT Porcine respiratory disease complex is a major health concern for the porcine industry, causing significant economic loss. In this study, a total of 156 samples from pigs referred to a diagnostic laboratory in Brazil for 15 months were analyzed by histopathology, bacterial isolation, PCR, and immunohistochemistry. Multiple infections were common, so 42.3% of the pigs had more than one pathogen detected in the lungs. Swine influenza virus was detected in 25.0% of the cases. Porcine circovirus type 2 was detected in 7.1% of the pigs, which was often associated with Pasteurella multocida. In addition, one case of porcine circovirus type 3 infection associated with granulomatous pneumonia was diagnosed. Bacteria were isolated in 125 cases, namely Pasteurella multocida (34.0%), Glaesserella (Haemophilus) parasuis (35.2%), Streptococcus suis (13.5%), and Actinobacillus pleuropneumoniae (7.7%). Mycoplasma hyopneumoniae was identified in 7.0% of the cases, and 18.6% of pigs carried Salmonella sp. The most common patterns of pulmonary inflammation were broncopneumonia, bronchointerstitial pneumonia, and pleuritis, in that order. This study demonstrated that histopathology is an efficient tool along with other laboratorial diagnostic tests for establishing an etiologic diagnosis in cases of porcine respiratory disease complex.

Effect of Carbonyl Cyanide Chlorophenylhydrazone on Intrabacterial Concentration and Antimicrobial Activity of Amphenicols against Swine Resistant Actinobacillus pleuropneumoniae and Pasteurella multocida

Effects and mechanism of carbonyl cyanide chlorophenylhydrazone (CCCP) on antimicrobial activity of florfenicol (FF) and thiamphenicol (TAP) were investigated against amphenicol-resistant Actinobacillus pleuropneumoniae and Pasteurella multocida isolated from diseased swine. Broth microdilution and time-kill assays indicated that CCCP dose-dependently and substantially (4-32 fold MIC reduction) improved amphenicol antimicrobial activity. When combined with CCCP at the lowest literature reported dose (2-5 μg/mL), 85% FF resistant A. pleuropneumoniae and 92% resistant P. multocida showed significantly reduced FF MICs (≥ 4-fold). In contrast, none or few of the susceptible A. pleuropneumoniae and P. multocida had FF MICs reduction ≥ 4-fold. 90% FF resistant A. pleuropneumoniae and 96% resistant P. multocida carried the floR gene, indicating strong association with the FloR efflux pump. With CCCP, the intracellular FF concentration increased by 71% in floR+ resistant A. pleuropneumoniae and 156% in floR+ resistant P. multocida strains but not the susceptible strains. The degree of reduction in TAP MICs was found consistently in parallel to FF for both bacteria. Taken together, partially attributed to blockage of drug-efflux, the combination of FF or TAP with CCCP at sub-cytotoxic concentrations was demonstrated and showed feasibility to combat amphenicol-resistant A. pleuropneumoniae and P. multocida isolated from diseased swine.

Assessment of animal diseases caused by bacteria resistant to antimicrobials: Swine

In this opinion, the antimicrobial-resistant bacteria responsible for transmissible diseases that constitute a threat to the health of pigs have been assessed. The assessment has been performed following a methodology based on information collected by an extensive literature review and expert judgement. Details of the methodology used for this assessment are explained in a separate opinion. A global state of play of antimicrobial resistant Escherichia coli, Streptococcus suis, Actinobacillus pleuropneumoniae, Pasteurella multocida, Glaeserella parasuis, Bordetella bronchiseptica, Staphylococcus aureus, Staphylococcus hyicus, Brachyspira hyodysenteriae, Trueperella pyogenes, Erysipelothrix rhusiopathiae, Streptococcus dysgalactiae, Mycoplasma hyosynoviae, Mycoplasma hyorhinis, Mycoplasma hyopneumoniae and Brachyspira pilosicoli has been provided. Among those bacteria, EFSA identified E. coli and B. hyodysenteriae with > 66% certainty as being the most relevant antimicrobial resistant bacteria in the EU based on the available evidence. The animal health impact of these most relevant bacteria, as well as their eligibility for being listed and categorised within the animal health law framework will be assessed in separate scientific opinions.

Management practices related to the control of gastrointestinal parasites on Swedish pig farms

Background

Internal parasites are common in pigs worldwide and may induce clinical disease or subclinical infections with negative effects such as poor weight gain and reduced welfare, which in turn affect productivity. Effective parasite control to reduce the negative impact of parasitic infections demands a combination of antiparasitic drugs as well as various hygiene and biosecurity practices. The aim of this study was to obtain information on current management practices and parasite control routines used on Swedish pig farms using an online questionnaire.

Results

Antiparasitic drugs were used on 69% of the farms routinely and were mainly administered to sows just prior to farrowing. Less than 5% of the herds conducted faecal analysis for parasites. Batchwise, age segregated rearing was common and overall, it was practiced for piglets, growers, and fatteners on 88, 80 and 75% of the farms, respectively. Large and medium sized farms appeared to apply stricter hygiene and biosecurity measures to the growing pigs compared to small farms. Dry sows were mainly housed in groups on deep litter straw beds and cleaning, as well as disinfection, between each group was less common compared to what was practiced for growing pigs. Outdoor access was rare and only occurred on organic and small farms. Most of the farms, 54, 74 and 82% of small, medium, and large sized herds respectively, reported to have less than 5% white spot lesions, caused by migrating A. suum larvae, registered at slaughter.

Conclusion

Several risk factors for parasite infections, such as bedding material, group housing and solid floors, are mandatory requirements by national law. However, it was evident from this study that although strategic hygiene and biosecurity practices appeared common, they were not practiced in all herds and less so for dry sows. Antiparasitic drugs were used frequently and mainly through routine prophylactic treatments without prior testing for parasites. A holistic approach is necessary when designing efficient parasite control programs, and it is essential that management factors and routine monitoring of parasites are given attention. This to achieve efficient parasite control and reduce the risk of unnecessary use of antiparasitic drugs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40813-021-00193-3.

Herd-level risk factors for chronic pleurisy in finishing pigs: a case-control study

Background

Chronic pleurisy is a common finding in slaughtered pigs in post-mortem meat inspection. The prevalence of pleurisy has been increasing during the last decade also in Finland. The aim of this prospective case-control study was to search for environmental, infectious and management-related herd-level risk factors for pleurisy in the slaughterhouse. Altogether 46 Finnish pig herds, including 25 control (low pleurisy prevalence in meat inspection) and 21 case (high pleurisy) herds, were enrolled in the study and visited during the tenth week of the rearing period of finishing pigs. Herd personnel were asked about basic herd information, management and environmental factors. Selected pigs were examined clinically, environmental parameters were measured and 15 blood samples per herd were taken during herd visits. Antibodies against Actinobacillus pleuropneumonia serotype 2 (APP2) and ApxIV toxin and swine influenza virus were measured. After the slaughter of study pigs, meat inspection results of the batch were gathered from slaughterhouses. Multivariate logistic regression model was built to identify possible risk factors for a herd to be a case herd (i.e. having high pleurisy values).

Results

Finishing herd type and herd size were observed to act as risk factors. None of clinical signs of pigs, management-related factors or environmental measurements were associated with herd status.

Conclusions

As previously known, in endemic and subclinical infections such as APP, herd factors are important, but detailed risk factors seem to be difficult to identify.

A descriptive study of acute outbreaks of respiratory disease in Norwegian fattening pig herds

BACKGROUND

Respiratory diseases are major health concerns in the pig production sector worldwide, contributing adversely to morbidity and mortality. Over the past years there was a rise in reported incidents of respiratory disease in pigs in Norway, despite population wide freedom from Aujeszky´s disease, porcine reproductive and respiratory syndrome, porcine respiratory corona virus and enzootic pneumonia. The main objective of this study was to investigate acute outbreaks of respiratory disease in conventional Norwegian fattening pig herds. The study included 14 herds. In seven herds with reported outbreaks of acute respiratory disease, data on clinical signs was recorded and samples for laboratory examination were collected. Diagnostic protocols were compared by parallel analysis of clinically healthy pigs from seven non-outbreak herds.

RESULTS

The most commonly reported clinical signs were sudden deaths and dyspnea. An average compartment morbidity of 60%, mortality of 4% and case fatality of 9% was recorded in the outbreak herds. Post-mortem examinations revealed acute lesions resembling porcine pleuropneumonia in all 28 pigs investigated from the outbreak herds and in 2 of the 24 (8%) pigs from the non-outbreak herds. Chronic lesions were recorded in another 2 pigs (8%) from the non-outbreak herds. Actinobacillus pleuropneumoniae serovar 8 was isolated from lungs and/or pleura from all tested pigs (n = 28) in the outbreak herds, and from 2 out of 24 pigs (8%) in the non-outbreak herds, one pig with an acute and another pig with a chronic infection. No other significant bacterial findings were made. Seroconversion to A. pleuropneumoniae antibodies was detectable in all outbreak herds analyzed and in six out of seven non-outbreak herds, but the risk ratio for seroconversion of individual pigs was higher (risk ratio 2.3 [1.50- 3.43 95% CI; P < 0.001]) in the outbreak herds. All herds tested positive for porcine circovirus type 2 and negative for influenza A viruses on oral fluid RT-qPCR.

CONCLUSION

The main etiological pathogen found during acute outbreaks of respiratory disease was A. pleuropneumoniae serovar 8. All pigs from outbreak herds had typical lesions of acute porcine pleuropneumonia, and only A. pleuropneumoniae serovar 8 was identified. Co-infections were not found to impact disease development.

A Systematic Review Analyzing the Prevalence and Circulation of Influenza Viruses in Swine Population Worldwide

The global anxiety and a significant threat to public health due to the current COVID-19 pandemic reiterate the need for active surveillance for the zoonotic virus diseases of pandemic potential. Influenza virus due to its wide host range and zoonotic potential poses such a significant threat to public health. Swine serve as a “mixing vessel” for influenza virus reassortment and evolution which as a result may facilitate the emergence of new strains or subtypes of zoonotic potential. In this context, the currently available scientific data hold a high significance to unravel influenza virus epidemiology and evolution. With this objective, the current systematic review summarizes the original research articles and case reports of all the four types of influenza viruses reported in swine populations worldwide. A total of 281 articles were found eligible through screening of PubMed and Google Scholar databases and hence were included in this systematic review. The highest number of research articles (n = 107) were reported from Asia, followed by Americas (n = 97), Europe (n = 55), Africa (n = 18), and Australia (n = 4). The H1N1, H1N2, H3N2, and A(H1N1)pdm09 viruses were the most common influenza A virus subtypes reported in swine in most countries across the globe, however, few strains of influenza B, C, and D viruses were also reported in certain countries. Multiple reports of the avian influenza virus strains documented in the last two decades in swine in China, the United States, Canada, South Korea, Nigeria, and Egypt provided the evidence of interspecies transmission of influenza viruses from birds to swine. Inter-species transmission of equine influenza virus H3N8 from horse to swine in China expanded the genetic diversity of swine influenza viruses. Additionally, numerous reports of the double and triple-reassortant strains which emerged due to reassortments among avian, human, and swine strains within swine further increased the genetic diversity of swine influenza viruses. These findings are alarming hence active surveillance should be in place to prevent future influenza pandemics.

Porcine circovirus type 2 promotes Actinobacillus pleuropneumoniae survival during coinfection of porcine alveolar macrophages by inhibiting ROS production

Actinobacillus pleuropneumoniae (APP) and porcine circovirus type 2 (PCV2) are both important pathogens of the porcine respiratory disease complex (PRDC), which results in significant worldwide economic losses. Recently, PCV2 and APP coinfection has been described in the worldwide pork industry, and represents an extremely complex situation in veterinary medicine. However, the mechanism of their coinfection has not been investigated. In this study, we found that PCV2 promoted APP adhesion to and invasion of porcine alveolar macrophages (PAMs) during coinfection. Additionally, PCV2 suppressed reactive oxygen species (ROS) production by inhibiting cytomembrane NADPH oxidase activity, which was beneficial for APP survival in PAMs in vitro. During coinfection, PCV2 weakened the inflammatory response and macrophage antigen presentation by decreasing TNF-α, IFN-γ and IL-4 expression, and reduced clearance of the invading bacteria. The host-cell experimental results were verified in a mouse model. The findings provide a deeper and novel understanding of porcine coinfection, and will be extremely helpful for the design of strategies for PRDC control.

Effect of oral KETOPROFEN treatment in acute respiratory disease outbreaks in finishing pigs

Background

Infection with respiratory pathogens can influence production as well as animal welfare. There is an economical and ethical need to treat pigs that suffer from respiratory diseases. Our aim was the evaluation of the possible effects of oral NSAID medication given in feed in acute outbreaks of respiratory disease in finishing pigs. The short- and long-term impact of NSAID dosing on clinical signs, daily weight gain, blood parameters and behaviour of growing pigs in herds with acute respiratory infections were evaluated. Four finishing pig farms suffering from acute outbreaks of respiratory disease were visited thrice after outbreak onset (DAY 0, DAY 3 and DAY 30). Pigs with the most severe clinical signs (N = 160) were selected as representative pigs for the herd condition. These pigs were blood sampled, weighed, evaluated clinically and their behaviour was observed. After the first visit, half of the pens (five pigs per pen in four pens totalling 20 representative pigs per herd, altogether 80 pigs in four herds) were treated with oral ketoprofen (target dose 3 mg/kg) mixed in feed for three days and the other half (80 pigs) with a placebo. In three of the herds, some pigs were treated also with antimicrobials, and in one herd the only pharmaceutical treatment was ketoprofen or placebo.

Results

Compared to the placebo treatment, dosing of ketoprofen reduced sickness behaviour and lowered the rectal temperature of the pigs. Clinical signs, feed intake or blood parameters were not different between the treatment groups. Ketoprofen treatment was associated with somewhat reduced weight gain over the 30-day follow-up period. Concentration analysis of the S- and R-enantiomers of ketoprofen in serum samples collected on DAY 3 indicated successful oral drug administration.

Conclusions

Ketoprofen mainly influenced the behaviour of the pigs, while it had no effect on recovery from respiratory clinical signs. However, the medication may have been started after the most severe clinical phase of the respiratory disease was over, and this delay might complicate the evaluation of treatment effects. Possible negative impact of ketoprofen on production parameters requires further evaluation.