Housing and management factors and breed predisposition for haemorrhagic bowel syndrome in swine

BACKGROUND

Haemorrhagic bowel syndrome (HBS) is a sporadically occurring disorder characterized by sudden death in pigs in combination with a pale and bloated carcass with no prior signs of disease. Most often HBS is affecting fattening pigs. Due to the good general health and performance before death as well as the time point of disease shortly prior to slaughter, this syndrome means a significant economic impact for the farm and is a major animal welfare concern. Furthermore, the cause or the causing agents have not yet been identified even though it is a worldwide known problem. The aim of this study was to detect possible risk factors for the occurrence of HBS with the focus on risk factors on herd level.

RESULTS

Management and feeding strategies of 97 Swiss fattening herds with high and low HBS incidence were assessed and examined to identify risk factors for the disease. Having only pigs sired by the PREMO® breed in the herd showed to be a significant risk factor for HBS (Odds Ratio (OR) = 147) as compared to having other breeds or a mixture of multiple breeds. Furthermore, pigs from two or more origins per batch compared to having only one origin per batch significantly increased the disease risk (OR = 52). Farms with 1 decimetre greater feeding place width per finisher pig have a lower HBS incidence (OR = 0.07). The frequency of cleaning of the distribution pipes (split up into categories, e.g. once a month) was associated with being a HBS case farm (p < 0.05).

CONCLUSION

The four factors identified in this study for the occurrence of HBS represent different aspects of the environment and management. This leads to the assumption that it is a multifactorial syndrome and a thorough examination of each herd individually is necessary to mitigate disease risk. This study suggests that part of the susceptibility to HBS is genetically determined. The reduction of HBS in the herd should be the main objective to improve the economic status of the herd and improve animal welfare.

Detection of Toxoplasma gondii-specific antibodies in pigs using an oral fluid-based commercial ELISA: Advantages and limitations

Toxoplasma gondii is a major food-borne parasite and undercooked meat of infected pigs represents an important source of infection for humans. Since infections in pigs are mostly subclinical, adequate diagnostic tests for use at the farm level are pursued. Oral fluid (OF) was shown to be a promising matrix for direct and indirect detection of infections with various pathogens in pigs. The objective of this study was to assess whether T. gondii infections in pigs could be diagnosed using an indirect ELISA kit adapted for OF samples (OF-ELISA). Routine serology and OF-immunoblot (IB) were used as standards for the comparison. For this, serial OF samples from sows (n = 8) and fatteners (n = 3) experimentally inoculated with T. gondii oocysts, individual field samples from potentially exposed sows (n = 9) and pooled OF samples from potentially exposed group-housed fatteners (n = 195 pig groups, including 2,248 animals) were analysed for antibodies against T. gondii by ELISA. For individual animals, OF-ELISA exhibited a relative diagnostic specificity of 97.3% and a relative diagnostic sensitivity of 78.8%. In experimentally infected animals, positive OF-ELISA results were observed from 1.5 weeks post inoculation (pi) until the end of the experimental setup (8 to 30 weeks pi); however, values below the estimated cut-off were occasionally observed in some animals despite constant seropositivity. In potentially exposed individual animals, OF- and serum-ELISA results showed 100% agreement. In group-housed fatteners, antibodies against T. gondii could be reliably detected by OF-ELISA in groups in which at least 25% of the animals were seropositive. This OF-ELISA, based on a commercially available serum-ELISA, may represent an interesting non-invasive screening tool for detecting pig groups with a high exposure to T. gondii at the farm level. The OF-ELISA may need further adjustments to consistently detect individual infected pigs, probably due to variations in OF antibody concentration over time.

Frequent Occurrence of Simultaneous Infection with Multiple Rotaviruses in Swiss Pigs

Rotavirus (RV) infections are the most important viral cause of diarrhea in piglets in Switzerland and are thought to cause substantial economic losses to the pig industry. However, no data are available on the occurrence and dynamics of the main porcine RV species, namely RVA, RVB, and RVC, and the diversity of the circulating strains. We therefore tested fecal samples from a cross-sectional (n = 95) and a longitudinal (n = 48) study for RVA, RVB, and RVC by real-time RT-PCR and compared the results of the cross-sectional study to postmortem findings. In addition, eight samples were fully genotyped by using next-generation sequencing. In the cross-sectional study, triple RV infections significantly correlated with diarrhea and wasting and were most frequent in the weaned age group. In the longitudinal study, the shedding of RV peaked one week after weaning and decreased thereafter. Here, mainly double infections were seen, and only a few animals showed diarrhea. The full-genome sequencing revealed a genotype pattern similar to other European countries and, importantly, co-infection by up to four RVA strains. Our results imply that the weaning of piglets may trigger not only RV shedding but facilitate co-infection of multiple RV species and strains in the same host.

Prevalence of tail lesions in Swiss finishing pigs

INTRODUCTION

Tail biting and lesions are common problems in modern pig production. In 2008 tail docking to prevent tail biting was banned in Switzerland. Since then pigs have been raised with intact tails. This study aimed to assess the current prevalence of tail lesions at Swiss abattoirs and comparing abattoir data with farm-specific data regarding potential risk factors for tail lesions. Data collection was performed in repetitive cycles of two weeks at four abattoirs during all consecutive seasons of one year. Gender, tail length and the tail tip condition were evaluated among other parameters. During 32 weeks in total, 195 704 pigs from 6112 batches from 2510 herds were evaluated. Overall, 63,2 % of the animals included in the analysis were slaughtered with a complete tail (lowest tail length score [TLS]), whereas 36,8 % showed a partial or total loss of the tail. The condition of the tail tip (tail tip condition score [TTCS]) was judged as being intact in 63,0 %, as a healed lesion in 23,7 %, an acute lesion in 1,3 % and a chronic lesion in 12,0 % of all cases. Male animals had significantly higher values for TLS and TTCS than female animals (P ≤ 0,05). TLS values were significantly higher in winter than in spring and summer (P < 0,001). TTCS values were significantly higher in fall than in spring and summer. TLS and TTCS values differed significantly (P < 0,001) between the four abattoirs. Only few significant correlations were found between values of TLS and TTCS and farm-specific data. Recording tail lesions at abattoirs is an accurate method to investigate the prevalence of tail lesions in fattening pigs. However, to monitor animal welfare on herd level, this method is very labor intensive. Moreover, data on tail lesions collected at the abattoir cannot replace veterinary on-farm examination for risk factor identification.

Development of a novel high resolution melting assay for identification and differentiation of all known 19 serovars of Actinobacillus pleuropneumoniae

Actinobacillus pleuropneumoniae is the etiological agent of porcine pleuropneumonia, a respiratory infectious disease responsible for global economic losses in the pig industry. From a monitoring perspective as well as due to the different courses of disease associated with the various serovars, it is essential to distinguish them in different herds or countries. In this study, we developed a novel high resolution melting (HRM) assay based on reference strains for each of the 19 known serovars and additional 15 clinical A. pleuropneumoniae isolates. The novel HRM comprises the species‐specific APP‐HRM1 and two serovar‐specific HRM assays (APP‐HRM2 and APP‐HRM3). APP‐HRM1 allowed polymerase chain reaction (PCR) amplification of apxIV resulting in an A. pleuropneumoniae specific melting curve, while nadV specific primers differentiated biovar 2 from biovar 1 isolates. Using APP‐HRM2 and APP‐HRM3, 13 A. pleuropneumoniae serovars can be determined by inspecting the assigned melting temperature. In contrast, serovar 3 and 14, serovar 9 and 11, and serovar 5 and 15 have partly overlapping melting temperatures and thus represent a challenge to accurately distinguish them. Consequently, to unambiguously ensure the correct assignment of the serovar, it is recommended to perform the serotyping HRM assay using a positive control for each serovar. This rapid and user‐friendly assay showed high sensitivity with 1.25 fg–125 pg of input DNA and a specificity of 100% to identify A. pleuropneumoniae. Characteristic melting patterns of amplicons might allow detecting new serovars. The novel HRM assay has the potential to be implemented in diagnostic laboratories for better surveillance of this pathogen.

Delivery of non-viral naked DNA vectors to liver in small weaned pigs by hydrodynamic retrograde intrabiliary injection

Hepatic gene therapy by delivering non-integrating therapeutic vectors in newborns remains challenging due to the risk of dilution and loss of efficacy in the growing liver. Previously we reported on hepatocyte transfection in piglets by intraportal injection of naked DNA vectors. Here, we established delivery of naked DNA vectors to target periportal hepatocytes in weaned pigs by hydrodynamic retrograde intrabiliary injection (HRII). The surgical procedure involved laparotomy and transient isolation of the liver. For vector delivery, a catheter was placed within the common bile duct by enterotomy. Under optimal conditions, no histological abnormalities were observed in liver tissue upon pressurized injections. The transfection of hepatocytes in all tested liver samples was observed with vectors expressing luciferase from a liver-specific promoter. However, vector copy number and luciferase expression were low compared to hydrodynamic intraportal injection. A 10-fold higher number of vector genomes and luciferase expression was observed in pigs using a non-integrating naked DNA vector with the potential for replication. In summary, the HRII application was less efficient (i.e., lower luciferase activity and vector copy numbers) than the intraportal delivery method but was significantly less distressful for the piglets and has the potential for injection (or re-injection) of vector DNA by endoscopic retrograde cholangiopancreatography.

Antimicrobial usage in Swiss fattening pig farms: is there still potential for improvement?

OBJECTIVE

The aim of this study was to analyze antimicrobial usage (AMU) in fattening pig farms that took part in the SuisSano/Safety + Health Programme in Switzerland over the year 2020 and to discuss the potential for further improvement. Usage was examined according to the antimicrobial's class and indication for use, with emphasis on highest priority critically important antimicrobials (HPCIAs).

METHODS

Data on AMU from 1411 farms, reported in an electronic treatment journal, was used. AMU was quantified through treatment incidence (TI) based on Swiss Defined Daily Doses (DDDch). Indication of use for each antimicrobial class was analyzed with particular focus on HPCIAs.

RESULTS

The total TI of all antimicrobials used in the farms corresponds to 8.9 DDDch per 1000 pig-days at risk, of which HPCIAs represented 2.6 %. A total of 140 farms (9.9 %) partake in HPCIAs usage, with tylosin (73.8 % of total HPCIA TI) and colistin (22.8 % of total HPCIA TI) being the most frequently antimicrobials used. The most common indication for treatment with HPCIAs was gastrointestinal disorders (62.1 % of total HPCIA TI).

CONCLUSION AND CLINICAL RELEVANCE

This study shows that the efforts made in recent years to foster prudent use of antimicrobials and, especially HPCIAs in Swiss pig production, have been successful. Indeed, 90.1 % (1271 of 1411) of the farms did not use any HPCIAs over the year 2020. Of the recorded treatments, HPCIA's represented only 2.6 % of the total TIs used in fattening pigs. Since many farms do not use any HPCIAs, knowledge can be obtained from these farms to identify practices which can further reduce or even stop HPCIAs usage. Moreover, information concerning indications for HPCIAs usage provide input concerning where treatment options other than HPCIAs should be explored by both farmers and veterinarians.

Screening of Swiss Pig Herds for Hepatitis E Virus: A Pilot Study

Hepatitis E virus (HEV) is an important cause of acute hepatitis in humans worldwide. In industrialised countries, most infections are caused by the zoonotic genotype 3. The main reservoir was found in pigs, with fattening pigs as the main shedders. The aim of this study was to establish a screening tool to detect HEV in pig farms. HEV-positive samples were sequenced using Sanger sequencing. First, different sample materials, including floor swabs, slurry, dust swabs and faeces were tested for HEV. Floor swabs turned out to give the best results and, in the form of sock swabs, were used for the screening of Swiss pig herds. A total of 138 pig farms were tested, with a focus on fattening pigs. Overall, 81 farms (58.8%) were HEV positive. Most sequences belonged to subtype 3h, in which they formed a specific cluster (Swiss cluster). In addition, subtype 3l and two unassigned sequences were detected. As a conclusion, sock swabs were found to be a helpful tool to screen pig herds for HEV and establish a sequence collection that may enable molecular epidemiology and support outbreak investigation and prevention.

Infertility due to defective sperm flagella caused by an intronic deletion in DNAH17 that perturbs splicing

Artificial insemination in pig (Sus scrofa domesticus) breeding involves the evaluation of the semen quality of breeding boars. Ejaculates that fulfill predefined quality requirements are processed, diluted and used for inseminations. Within short time, eight Swiss Large White boars producing immotile sperm that had multiple morphological abnormalities of the sperm flagella were noticed at a semen collection center. The eight boars were inbred on a common ancestor suggesting that the novel sperm flagella defect is a recessive trait. Transmission electron microscopy cross-sections revealed that the immotile sperm had disorganized flagellar axonemes. Haplotype-based association testing involving microarray-derived genotypes at 41,094 SNPs of six affected and 100 fertile boars yielded strong association (P = 4.22 × 10-15) at chromosome 12. Autozygosity mapping enabled us to pinpoint the causal mutation on a 1.11 Mb haplotype located between 3,473,632 and 4,587,759 bp. The haplotype carries an intronic 13-bp deletion (Chr12:3,556,401-3,556,414 bp) that is compatible with recessive inheritance. The 13-bp deletion excises the polypyrimidine tract upstream exon 56 of DNAH17 (XM_021066525.1: c.8510-17_8510-5del) encoding dynein axonemal heavy chain 17. Transcriptome analysis of the testis of two affected boars revealed that the loss of the polypyrimidine tract causes exon skipping which results in the in-frame loss of 89 amino acids from DNAH17. Disruption of DNAH17 impairs the assembly of the flagellar axoneme and manifests in multiple morphological abnormalities of the sperm flagella. Direct gene testing may now be implemented to monitor the defective allele in the Swiss Large White population and prevent the frequent manifestation of a sterilizing sperm tail disorder in breeding boars.

Evaluation of oral fluids for surveillance of foodborne and zoonotic pathogens in pig farms

The use of oral fluid (OF) to detect zoonotic pathogens in pigs has been only scarcely assessed. We evaluated OF as a potential specimen for detection by culture of methicillin-resistant Staphylococcus aureus (MRSA) and Yersinia enterocolitica, and the detection of antibodies against Salmonella spp. and hepatitis E virus (HEV) using commercial ELISAs. Samples from 33 pig farms were collected at the beginning and end of the fattening period. Results of the OF samples were compared with the results of serum samples and nasal swabs from individual pigs and pen floor fecal samples, using the Cohen kappa (κ) and the McNemar test. For Salmonella spp. antibodies, OF samples were negative, although the corresponding serum samples were positive. The detection of HEV antibodies in sera and OF had agreement at the first sampling, and poor and significant agreement at the second sampling (κ = 0.185, McNemar p = 0.238; κ = 0.088, McNemar p < 0.001). At both sampling times, the detection of MRSA in nasal swabs and OF showed agreement (κ = 0.466, McNemar p = 0.077; κ = 0.603, McNemar p = 1); agreement was seen for the detection of Y. enterocolitica in fecal and OF samples (κ = 0.012, McNemar p = 0.868; κ = 0.082, McNemar p = 0.061, respectively). According to the McNemar test, the use of pen-based OFs is more feasible for the detection of MRSA and Y. enterocolitica by culture than is detection of antibodies by commercial ELISA.

Establishment of a Mass-Spectrometry-Based Method for the Identification of the In Vivo Whole Blood and Plasma ADP-Ribosylomes

Blood and plasma proteins are heavily investigated as biomarkers for different diseases. However, the post-translational modification states of these proteins are rarely analyzed since blood contains many enzymes that rapidly remove these modifications after sampling. In contrast to the well-described role of protein ADP-ribosylation in cells and organs, its role in blood remains mostly uncharacterized. Here, we discovered that plasma phosphodiesterases and/or ADP-ribosylhydrolases rapidly demodify in vitro ADP-ribosylated proteins. Thus, to identify the in vivo whole blood and plasma ADP-ribosylomes, we established a mass-spectrometry-based workflow that was applied to blood samples collected from LPS-treated pigs (Sus scrofa domesticus), which serves as a model for human systemic inflammatory response syndrome. These analyses identified 60 ADP-ribosylated proteins, 17 of which were ADP-ribosylated plasma proteins. This new protocol provides an important step forward for the rapidly developing field of ADP-ribosylation and defines the blood and plasma ADP-ribosylomes under both healthy and disease conditions.

Occurrence of Escherichia coli non-susceptible to quinolones in faecal samples from fluoroquinolone-treated, contact and control pigs of different ages from 24 Swiss pig farms

BACKGROUND

Despite their indispensability in human medicine, fluoroquinolones (FQ) are used for the treatment of bacterial infections in farm animals which increases the risk of transferring FQ-resistant bacteria into the environment and via the food chain to humans. The objectives of this observational study were to follow-up of the presence of quinolone non-susceptible Escherichia coli (QNSE) qualitatively and quantitatively in faecal samples of pigs at four time points (2 weeks old, 4 weeks old, 2 weeks post weaning and during fattening period). Moreover differences between groups of FQ-treated pigs, pigs with contact to treated pigs and control pigs were investigated. Additionally, quinolone and FQ resistance of Escherichia coli isolates of the faecal samples were investigated by determining minimum inhibitory concentrations (MICs).

RESULTS

40.9% of 621 fecal samples contained QNSE. Proportion of samples with detectable QNSE from treated and contact pigs did not differ significantly and were highest in piglets of 2 and 4 weeks of age. However, the proportions of samples with QNSE were significantly lowest in control pigs (7/90; 7.8%; CI = 3.5-14.7%) among all groups. Also, the number of colony-forming units was lowest in both weaners and fattening pigs of the control group compared to treated and contact groups. Following CLSI human breakpoints, in total, 50.4% out of 254 isolates in faecal samples were intermediate or resistant to ciprofloxacin.

CONCLUSIONS

QNSE were present in faeces of pigs independent of age or FQ background but significantly less were found in pigs from farms without FQ usage. Due to the long half-life of FQ, it is likely that only a prolonged absence of fluoroquinolone treatments in pig farming will lead to a reduced frequency of QNSE in the farm environment. Solutions need to be found to minimise the emergence and transfer of quinolone and FQ-resistant bacteria from treated pigs to contact pigs and to farms without FQ usage.

[Field trial for eradication of methicillin- resistant Staphylococcus aureus (MRSA) in a pig breeding farm by bacteriophages]

INTRODUCTION

In recent years, Livestock Associated Methicillin-Resistant Staphylococcus aureus (LA-MRSA) are found frequently in pigs. The colonization of the care staff with LA-MRSA is strongly associated with the intensity and duration of animal contact and LA-MRSA herd prevalence. In human medicine, staphylococcal infections have been controlled successfully by topical or systemic administration of Staphylococcus - associated bacteriophages. Therefore, the present study investigated the effect of a bacteriophage cocktail on skin and mucosal colonization of pigs with MRSA in a pig farm with high MRSA prevalence. In a first experiment, the sows were washed with a bacteriophage cocktail and nose, mouth and vagina were rinsed before the sows were admitted to the farrowing house. Then, 10 ml of the bacteriophage cocktail was administered daily to the sows over the feed until weaning. The suckling piglets were sprayed and sampled twice a week during the suckling period and treated with the bacteriophage cocktail over the feed during the weaning period. In further experiments, the weaning room was nebulized three times a day with a bacteriophage cocktail and different concentrations of bacteriophages were added to the drinking water via Dosatron®. None of the experiments, however, showed an eradication of MRSA neither in nose nor in feces.

Suitability of testicular tissue fluid from castrated piglets to verify sow -vaccination status and herd monitoring

INTRODUCTION

In a proof of concept, PCV2-specific IgG-antibodies from testicular tissue fluid of seven-day-old castrated piglets were measured to verify the vaccination status of their mothers. Twelve randomly selected sows were vaccinated twice during the last third of gestation with a PCV2 vaccine, while ten controls received only adjuvant. PCV2- specific IgG-antibody titers of serum and colostrum from the sows were correlated with PCV2-specific IgG-antibody titers of serum and testicular tissue fluid of their castrated male offspring. Vaccinated sows showed significantly higher average PCV2-specific IgG-antibody titers in serum (29250 ELISA units, EU) and colostrum (65410 EU) compared to 980 EU and 2630 EU of the control group, respectively. Moreover, significantly higher average concentrations of antibodies were also measured in the serum (9362 EU vs. 247 EU) and the testicular tissue fluid (4022 EU vs. 354 EU) of piglets from vaccinated compared to piglets from adjuvant administered sows. Importantly, a strong linear correlation between PCV2-specific IgG-antibodies in the serum of the piglets and in their testicular tissue fluid was found (rs = 0.9148). PCV2-specific IgG-antibody titers of testicular tissue fluid from five randomly selected piglets allowed the determination of the vaccination status of the herd with a reliability of 98% for vaccinated and 73% for unvaccinated sows. Furthermore, using castration waste products is a very animal friendly method to replace painful and time-consuming blood samplings for herd monitoring or to verify vaccination status.

[Interventions and treatments of farm animals by non-veterinarians: quo vadis?]

INTRODUCTION

The increasing professionalization and the cost pressure on farms combined with a decreasing availability of veterinary expertise procures the demand for treatments and interventions performed by non-veterinarians. A current survey resulting in 56 responses of food animal practitioners showed that a majority delivered pour-on anthelmintics, drugs for oral application and ointments after respective instruction to farmers. Udder injectors, antimicrobials and vaccines were handled more restrictively, but even hormones were committed by more than half of the veterinarians to livestock owners. In respect to interventions, most practitioners supported that farmers perform functional foot trimming, administration of boli, inseminations, dehorning and castrations of calves. By contrast, many veterinarians refused that farmers apply intravenous injections, insert a trocar or treat sole ulcers. In respect to the future development, implications of non-veterinarian interventions on animal welfare, consumer protection and drug safety have to be considered. Indispensable are qualification and skills of the person performing interventions which can be acquired by certificated training courses. Moreover, a basic conception and taking responsibility in particular for application of veterinary drugs is mandatory - in this respect, at present marked deficits exist among many farmers. Based on the current legal situation, several interventions can be delegated to non-veterinarians, but the technical responsibility for the proper implementation is due to the veterinarian. This includes an evaluation of interventions and treatments on a regular basis together with the farmer. On this basis, the assessment of clinical symptoms as well as the initial treatment can be useful and appropriate to ensure a rapid therapy especially in animals suffering from factorial diseases. Having in mind profound differences in respect to the competence of non-veterinarians, general procedures to deliver drugs and to delegate interventions have to be rejected. Advanced diagnostic procedures and the prescription of veterinary drugs remain an exclusive mission of the veterinarian.

Antimicrobial Usage Among Different Age Categories and Herd Sizes in Swiss Farrow-to-Finish Farms

In the Swiss pig sector, the usage of antimicrobials has been recorded, evaluated and systematically reduced on a voluntary basis since 2015. This monitoring has been carried out using various methods thereby enabling continuous national scrutiny as well as international comparisons. To gain a better understanding of the dynamics of the antimicrobial usage on Swiss farms, consumption data of farrow-to-finish farms were analyzed for (i) the within-herd relationships among different age categories and (ii) the influence of the herd size. The data were collected on 71 farms for the year 2017, encompassing the amount of active ingredients and number of defined daily doses Switzerland (nDDDch) in total, and stratified for the different age categories of piglets, weaners, fattening pigs, and sows. The differences in nDDDch per animal among the age categories were determined by a Wilcoxon test and subsequent post-hoc analysis according to Bonferroni. The within-herd relationship among the individual age categories as well as the influence of the herd size on nDDDch per animal measured as kept sows were analyzed by simple linear regression. The evaluation of the treatment days showed that 50% of the nDDDch were used in piglets, 44% for weaners, and 3% each for fattening pigs and sows. Compared to the other age categories, the examination of the number of nDDDch per animal showed a significantly higher number for sows, whereas for fattening pigs the number was significantly lower (P < 0.01). The farm-based analysis using linear regression showed a relationship between antimicrobial usage in sows and piglets (P < 0.001; adj. R² = 0.19). Similarly, a significant relationship between larger herd size and increased antimicrobial usage was observed (P = 0.02; adj. R² = 0.06). The present study provides an insight into the antimicrobial treatment dynamics of farrow-to-finish farms. In particular, the age categories piglets and sows—with their higher number of treatment days in total or per animal—are of interest regarding the potential reduction in antimicrobial usage. Likewise, larger farms with higher management requirements were found to be of particular importance for the reduction of antimicrobial usage. Monitoring programs should therefore evaluate different age categories separately to identify problems for individual farms.

Porcine Circovirus Type 2 Pathogenicity Alters Host's Central Tolerance for Propagation

Porcine circovirus type 2 (PCV2) infections and resulting diseases are a worldwide threat to pig production. PCV2 bears a uniqueness that allows for us to understand more about chronic infections and the immune system in general. The virus can be phylogenetically subdivided into PCV2a to PCV2h genotypes. Although vaccination against PCV2 has been seen to prevent the manifestation of PCV disease, PCV2 still lingers as subclinical infections in all developmental stages of pigs. The “slow and low” tactic gives PCV2 a particular advantage in a host’s immune surveillance. Since the inception of the PCV2 associated panzootic, research scientists have been trying to understand the pathogenicity of PCV2. Different research groups found that one genotype group member was more pathogenic than others. We found, in our weaner infection model with in vivo transfection of different recombinant PCV2 genotype group members that these viruses alter T cell maturation in the thymus, including host’s central tolerance. Here, we extend these original observations by showing that PCV2 infected cells were also found in proximity within the female and male reproductive organs of stillborn pig fetuses. These PCV2 pools were sufficient in infecting three and half-day-old embryos in sows. Furthermore, the dominant PCV2 group member was more pathogenic in our weaner infection model. PCV2 pre-immunocompetence infection makes PCV2 recognized by central immune tolerance as belonging to the host. This also explains why pathogenicity is not a genetically intrinsic characteristic of PCV2; however, the dominance of any one PCV2 genotype group member leads to a more efficient deletion of the T cells against that specific genotype group member in the thymus.

Agreement of Benchmarking High Antimicrobial Usage Farms Based on Either Animal Treatment Index or Number of National Defined Daily Doses

Introduction: While treatment frequency as an indicator of antimicrobial consumption is often assessed using defined doses, it can also be calculated directly as an Animal Treatment Index (ATI). In this study, the correlation of calculating antimicrobial usage on Swiss pig farms using either national Defined Daily Doses (DDDch) or an ATI (number of treatments per animal per year) and the agreement between the different methods for the identification of high usage farms were investigated.

Material and Methods: The antimicrobial consumption of 893 Swiss pig herds was calculated separately for suckling piglets, weaned piglets, fattening pigs, lactating and gestating sows using the indicators nDDDch (number of DDDch) per animal per year and ATI. Correlations between the indicators were investigated by calculating Spearman's Rho coefficients. The 5, 10, and 25% highest usage farms were determined by applying both methods and the interrater reliability was described using Cohen's Kappa coefficients and visualized by Bland-Altman plots.

Results: The Spearman's Rho coefficients showed strong correlations (r > 0.5) between nDDDch/animal/year and ATI. The lowest coefficient was shown for the correlation of both indicators in gestating sows (r = 0.657) and the highest in weaned piglets (r = 0.910). Kappa coefficients identifying high usage farms were the highest in weaned piglets (k = 0.71, 0.85, and 0.91, respectively for 5, 10, and 25% most frequent users) and the lowest in gestating sows (k = 0.54, 0.58, and 0.55 for 5, 10, and 25% most frequent users).

Conclusions: In general, the investigated indicators showed strong correlations and a broad agreement in terms of the calculated levels of antimicrobial usage and the identification of high usage farms. Nevertheless, a certain proportion of the farms were defined differently depending on the indicator used. These differences varied by age category and were larger in all age categories except weaned piglets when a higher percentage benchmark was used to define high usage farms. These aspects should be considered when designing scientific studies or monitoring systems and considering which indicator to use.

Impact of the Suissano Health Programme on antimicrobial usage on 291 pig farms in Switzerland

BACKGROUND

In 2015, in Switzerland the Suissano Health Programme was implemented in pig production to improve transparency for antimicrobial usage (AMU) and to reduce the usage of fluoroquinolones (FQ), macrolides and cephalosporins, representing highest priority critically important antimicrobials.

METHODS

In the presented cohort study, the impact of the Suissano programme on the AMU of 291 pig farms between 2016 and 2017 was investigated. AMU was calculated in total numbers of defined course doses (nDCDch) for all farms in the programme. For each single farm the nDCDch/animal/year was determined for four different age categories (suckling piglets, weaned piglets, fattening pigs, sows) as well as each antimicrobial substance separately. Trends between 2016 and 2017 were investigated for all farms as well as the 25 per cent with the highest usage of antimicrobials (high users) separately.

RESULTS

Total AMU measured in nDCDch declined by 23 per cent between 2016 and 2017, but statistically significant differences could not be observed when comparing the data sets of the individual farms. A significantly reduced usage of FQ could be demonstrated in suckling piglets (P=0.003), weaned piglets (P=0.006) and sows (P=0.008) in 2017 compared with 2016. For high users, a significant reduction of total AMU could be shown in suckling piglets (P=0.02), weaned piglets (P=0.0004) and fattening pigs (P=0.01).

CONCLUSION

This study demonstrated a significant reduction in the usage of FQs in suckling piglets, weaned piglets and sows as well as total AMU in suckling piglets, weaned piglets and fattening pigs on high-usage farms.

[Use of antibiotics in Swiss piglet production and fattening farms]

INTRODUCTION

In 164 randomly selected Swiss piglet production farms and 101 fattening farms, the indication for antibiotic use in 2012/2013 was recorded and an animal treatment index (TBI) was calculated for each age group. Sows were treated on average 0.9 days per year mainly due to mastitis-metritis-agalactia (MMA). Suckling piglets were treated on average 0.5 days per production cycle, mainly due to diarrhea and polyarthritis. Weaned piglets were treated during 4.4 days, especially due to diarrhea, polyarthritis and wasting. In fattening pigs, treatments were mainly due to diarrhea and HPS-suspicion, and lasted on average 4.8 days. In sows, antibiotics were used prophylactically on 22.6% of the treatment days, in suckling piglets on 50.5%, in weaners on 86.1% and in fattening pigs on 79.0% of the treatment days. A prophylactic oral antibiotic group therapy did not have a significant positive effect on daily weight gain of fattening pigs, nor was it able to reduce the number of individual or group therapies. In farms with prophylactic oral group therapy, the mortality rate during the first two fattening weeks even tended to be higher (p=0.06) than in farms without oral group therapy. Highest priority critically important antibiotics were used in 22.6% of all treatment days in sows, in 37.5% in suckling piglets, in 17.2% in weaned piglets and in 27.3% in fattening pigs. In many farms, antibiotics were not prescribed and used according to the rules of "prudent use".

[Analyses of antimicrobial usage in 598 pig farms in Switzerland in 2017]

INTRODUCTION

Antimicrobial usage was analyzed in 598 Swiss pig farms as part of the SuisSano Health Program in 2017. Antimicrobial usage was calculated on the basis of the prescriptions of the veterinarians using the standard dosages DCDCH (Defined Course Dose for Switzerland) and the amount of active substance by weight. Usage was analyzed based on the active antimicrobial class, pharmaceutical form age category (suckling piglets, weaned piglets, fattening pigs, sows) and stock type (breeding farms, fattening farms, farrow-finish farms and sow pool systems (SPS). A total amount of 610 kg antimicrobials or 894,688 DCDCH standard doses were used. The proportion of Highest Priority Critically Important Antimicrobials (HPCIAs) of the total antimicrobial usage was 2.5% for breeding sows, 4.5% for piglets, and 2.7% for fattening pigs based on the number of treatments in DCDCH/animal/year. In contrast weaning piglets showed a calculated proportion of 26%, of which 18% was due to polypeptides (colistin). Suckling piglets produced in SPS stocks were treated significantly more frequently than suckling piglets from other farms (P.

Thermal field formation during wIRA-hyperthermia: temperature measurements in skin and subcutis of piglets as a basis for thermotherapy of superficial tumors and local skin infections caused by thermosensitive microbial pathogens

Purpose: The temporal and spatial formation of the temperature field and its changes during/upon water-filtered infrared-A (wIRA)-irradiation in porcine skin and subcutis were investigated in vivo in order to get a detailed physical basis for thermotherapy of superficial tumors and infections caused by thermosensitive microbial pathogens (e.g., Mycobacterium ulcerans causing Buruli ulcer). Methods: Local wIRA-hyperthermia was performed in 11 anesthetized piglets using 85.0 mW cm^-2, 103.2 mW cm^-2 and 126.5 mW cm^-2, respectively. Invasive temperature measurements were carried out simultaneously in 1-min intervals using eight fiber-optical probes at different tissue depths between 2 and 20 mm, and by an IR thermometer at the skin surface. Results: Tissue temperature distribution depended on incident irradiance, exposure time, tissue depths and individual 'physiologies' of the animals. Temperature maxima were found at depths between 4 and 7 mm, exceeding skin surface temperatures by about 1-2 K. Tissue temperatures above 37 °C, necessary to eradicate M. ulcerans at depths <20 mm, were reached reliably. Conclusions: wIRA-hyperthermia may be considered as a novel therapeutic option for treatment of local skin infections caused by thermosensitive pathogens (e.g., in Buruli ulcer). To ensure temperatures required for heat treatment of superficial tumors deeper than 4 mm, the incident irradiance needed can be controlled either by (a) invasive temperature measurements or (b) control of skin surface temperature and considering possible temperature increases up to 1-2 K in underlying tissue.

Detection of antibodies to Toxoplasma gondii in oral fluid from pigs

Toxoplasma gondii-infected pigs play a major role as a source of infection for humans and detection of high-risk herds is essential to implement control measures at the farm level. The aim of this study was to determine whether oral fluid (OF) could be used as a matrix to detect antibodies against T. gondii in infected pigs by immunoblot (IB). For this, OF from experimentally inoculated sows (n = 8) (serial samples) and naturally exposed group-housed fatteners (n = 42 groups, one sample/group) were analysed for IgG and IgA against T. gondii-SAG1 antigen by IB. Simultaneously, each animal was serologically tested for anti-T. gondii IgG by ELISA. Specific IgG was detected in the sera of all inoculated sows from 2 to 3 weeks post inoculation (pi) and in 3.4 to 92% of the pigs in 13 out of 42 groups. Experimentally inoculated sows showed positive OF-IB results for IgA (100%) and IgG (87.5%) at 1.5 weeks pi and continued yielding positive results for IgA (87.5-75%) and IgG (50%) until 4 weeks pi; however, from 8 weeks pi the frequency of detection of both isotypes was lower, despite constantly positive IgG values in serum-ELISA. Interestingly, consecutive daily samplings for 4 days at 13 and 30 weeks pi showed inconsistent results for some sows, showing that the antibody concentration in OF is prone to timely variations. Pooled OF from groups with 91 and 92% of seropositive pigs yielded positive IB results for IgG and IgA. Fattener groups with ≤13% of seropositive pigs gave negative IB results to both isotypes. Our results showed that antibodies to T. gondii can be detected in OF from infected pigs, and that IgA seems to be a more adequate target than IgG. Although OF does not seem to be a robust matrix to assess the serological status for T. gondii in individual animals, this diagnostic approach represents an interesting non-invasive, low-cost and animal welfare friendly option as a screening method at the farm level to determine high exposure to T. gondii in the herd.

Influence of mastitis metritis agalactia (MMA) on bone and fat metabolism

Mastitis metritis agalactia (MMA) is a common disease in post-partum sows and has a negative effect on sows' longevity as well as on sows' and piglets' health. MMA leads to an inflammatory state. The aim was to investigate the impact of MMA on bone and fat metabolism. The hypothesis was that it is possible to predict MMA by measuring ketone bodies and bone markers. Blood samples from 175 sows were taken within 72 hr after farrowing. Serum was analysed for 25-hydroxyvitamin D (25-(OH)-D), serum crosslaps (CTX-I), osteocalcin (OC), alkaline phosphatase (ALP), calcium (Ca), magnesium (Mg), phosphorus (P), parathyroid hormone (PTH), triglycerides (TG), beta-hydroxybutyric acid (BHB), tumour necrosis factor-alpha (TNF-α) and haptoglobin. Spontaneous urine was collected, and pH value was measured in addition to Ca and P. A proximate analysis of the sows' diets was performed. Age, litter size, body condition score (BCS) and clinical signs of MMA were recorded for each sow. A multivariable logistic regression was undertaken with disease status (MMA or healthy) as the dependent variable. Significance was accepted at p < .05. MMA sows had a poorer BCS (p < .001) in relation to healthy sows. Age and number of piglets did not differ. MMA sows showed increased serum CTX-I (p = .004) and decreased serum OC (p < .001). Concentrations of P (p = .007), activity of ALP (p = .002) and BHB (p = .019) as well as TNF-α (p < .001) and haptoglobin (p = .048) concentrations were increased in MMA sows. No difference in urinary pH value between MMA and healthy sows was found. Our results are in accordance with the known fact that sows are in an extreme catabolic state peripartum. Bone metabolism in MMA sows is much more negatively affected than in healthy sows post-partum, due to inflammatory processes shown by higher concentrations of pro-inflammatory cytokines.

Occurrence of quinolone-resistant Escherichia coli in environmental samples from a sow pool system in Switzerland

INTRODUCTION

Fluoroquinolones (FQ) undergo minimal metabolization in animals and are excreted via faeces and urine, where they enter the environment almost unchanged. In this study we investigated the presence of quinolone-resistant Escherichia coli (E. coli) in the environment of 65 farms of a sow pool system in Switzerland. Two hundred and seventy-nine samples from liquid manure and wipes of dust and pen walls were collected and the use of FQ on the farms was investigated. From 45% of dust samples, 52% of pen wall samples and 69% of liquid manure samples quinolone-resistant E. coli (QRE) were cultivated. Significant higher counts of quinolone-resistant colonies were found in liquid manure samples than in dust (p < 0.01) or pen wall samples (p < 0.05). Samples from breeding farms were significantly more often positive than samples from fattening farms (p < 0.01). Samples taken from farms using FQ were significantly more frequently positive for QRE than samples from farms without FQ usage (p < 0.01). On 97% of the farms with FQ use and 85% (23/27) of the farms without FQ use QRE could be found in at least one sample (no significant difference). Overall, QRE were widespread in the environment of the investigated pig farms.

Antimicrobial Drug Consumption on Swiss Pig Farms: A Comparison of Swiss and European Defined Daily and Course Doses in the Field

Defined Daily Doses (DDD) and Defined Course Doses (DCD) have been established in both human and veterinary medicine in order to standardize the measurement of treatments in a population. In 2016 the European Medicines Agency published average defined daily dose (DDDvet) and defined course dose (DCDvet) values for antimicrobial agents used in livestock production. Similarly, national defined doses (DDDch and DCDch) for the pig sector in Switzerland have recently been determined. The aim of this study was to compare the outcome of calculating antimicrobial consumption based on either DDDvet/DCDvet or DDDch/DCDch. Data from 227 Swiss pig farms describing antimicrobial use in 2015 was collected. The numbers of treatment days and treatments were calculated using DDDvet/DCDvet and DDDch/DCDch respectively, for each farm in total and for different antimicrobial classes. Associations between calculated numbers of DDDvet/DCDvet and DDDch/DCDch on farm level were investigated. In addition, differences concerning antimicrobial use were investigated between different production types of farms (piglet-producer, finishing farm or farrow-to-finishing farm). Using DDDch/DCDch values we calculated 1,805,494 treatment days and 433,678 treatments compared to 1,456,771 treatment days (19% ratio) and 303,913 treatments (30% ratio) based on DDDvet/DCDvet. Penicillins (21.4/26.6%), polypeptides (18.6/27.6%) and fluoroquinolones (9.5/8.8%) were the most frequently used classes of antimicrobials based on calculation using both DDDch and DDDvet. Similar findings were observed for complete treatments (DCDch/vet) (penicillins: 52.8/39.6%; polypeptides: 7.8/14.2%; fluoroquinolones: 13.2/12.9%). The number of treatment days or treatments per farm was higher for piglet-producers and farrow-to-finishing farms compared to finisher farms regardless of whether Swiss or European DDD or DCD values were used for the calculation (each P < 0.001). Similar results for antimicrobial use (AMU) obtained at farm level were observed when calculated either by Swiss or European definitions. Nevertheless, marked differences could be observed in the assessment of the use of specific antimicrobial classes in the field based on DDDvet/DCDvet compared to DDDch/DCDch.

Phenotypic and genotypic characteristics of Escherichia coli with non-susceptibility to quinolones isolated from environmental samples on pig farms

Background

In the last decade, the growth of the pig-farming industry has led to an increase in antibiotic use, including several used in human medicine, e.g. (fluoro)quinolones. Data from several studies suggest that there is a link between the agricultural use of antibiotics and the prevalence of antibiotic-resistant bacteria in the pig farm environment, including (fluoro)quinolone resistance. This poses a threat to human and animal health. Our goal was to phenotypically and genotypically characterize 174 E. coli showing non-susceptibility to quinolones isolated from environmental samples from pig farms. Antimicrobial susceptibility testing (AST) was performed using the disk diffusion method. PCR and sequence analysis were performed to identify chromosomal mutations in the quinolone resistance-determining regions (QRDR) of gyrA and the isolates were screened for the presence of the plasmid-mediated quinolone resistance (PMQR) genes aac-(6')-Ib-cr, qepA, qnrA, qnrB, qnrC, qnrD and qnrS.

Strain relatedness was assessed by phylogenetic classification and multilocus sequence typing (MLST).

Results

Of 174 isolates, 81% (n = 141) were resistant to nalidixic acid, and 19% (n = 33) were intermediately resistant. Overall, 68.4% (n = 119) were multidrug resistant. This study revealed a prevalence of 79.9% (n = 139) for gyrA QRDR mutations, and detected 21.8% (n = 38) isolates with at least one PMQR gene. The two most frequently detected PMQR genes were qnrB and qnrS (13.8% (n = 24) and 9.8% (n = 17, respectively). E. coli belonging to phylogenetic group A (48.3%/n = 84) and group B1 (33.3% /n = 58) were the most frequent. E. coli ST10 (n = 20) and ST297 (n = 20) were the most common STs.

Conclusions

E. coli with non-susceptibility to quinolones are widespread among the environment of Swiss pig farms and are often associated with an MDR phenotype. In several cases these isolates possess at least one PMQR gene, which could spread by horizontal gene transfer. E. coli from pig farms have diverse STs, some of which are associated with human and animal disease.

Electronic supplementary material

The online version of this article (10.1186/s40813-019-0116-y) contains supplementary material, which is available to authorized users.

[Defining daily doses and total doses for the measurement of antibiotic usage in Swiss pig production]

INTRODUCTION

A significant Antibiotic-Monitoring-System is essential to analyse the use of antibiotics and to a better understanding of trends in resistance development. In human and veterinary medicine, for example, a system based on defined daily and treatment doses (Defined Daily Dose: DDD and Defined Course Dose: DCD) is applied. These definitions can be used to estimate the number of treatment days and treatments with antimicrobial agents in a population. For veterinary medicine, the European Medicines Agency (EMA) has published the European values DDDvet and DCDvet in the farm animal sector. The aim of this study was to define Swiss daily and treatment doses (DDDch and DCDch) for the treatment of pigs and to compare them with the EMA values in order to investigate the differences between individually collected national doses and average international doses. For the comparison, the quotient of Swiss and European values was calculated and the influence of the application form of an active substance and the number of active substances contained in a preparation was investigated. One hundred and three veterinary preparations with 138 active substances were assigned a DDDch and DCDch value. A comparison with EMA values was possible for 118 active substances. The comparison showed median values of 0.91 for the daily doses and 0.90 for the treatment doses, so that the daily and treatment doses in Switzerland are lower than the corresponding EMA doses. Both the form of application (injection solutions: 1.00; premixes: 0.76; P=0.02) and the number of active substances in the preparation (one active substance: 1.00; two active substances: 0.76; three active substances: 0.43; each P.

[Milk production without use of -antibiotics]

INTRODUCTION

At present, the usage of antimicrobial agents in organic dairy farming is a subject of controversial public debate because of its impact on animals, humans and the environment. This study shows how farms can be successfully managed without using antimicrobials for udder diseases. Thereby, animal welfare and targeted low bulk tank somatic cell counts should not be neglected. The operating data analysed in this study was collected during feeding and milking time on 18 swiss dairy farms that have not been treating diseased udders with antibiotics for at least 3 years. This study is a cross-sectional study. Farmers put the focus on breed characteristics such as a high life performance, low bulk tank somatic cell counts over several lactations, animals with a calm character, and small-formed cows with a deep flank. A trend towards dual-purpose breeds was observed. Few persons were involved in the milking process. Moreover, 94% of the farmers were raising their own young cattle directly on the farm. Consequently, animal transport has been minimized. Furthermore, clear management practices and work processes as well as a good animal observation influenced decisively the production success. additionally some farmers used phytotherapy, homeopathy and tried and true home remedies.

Clinical cystoisosporosis associated to porcine cytomegalovirus (PCMV, Suid herpesvirus 2) infection in fattening pigs

Cystoisospora (syn. Isospora) suis is the causative agent of neonatal porcine coccidiosis and one of the main causes of diarrhoea in suckling piglets worldwide. Infection with porcine cytomegalovirus (PCMV, Suid herpesvirus 2) causes inclusion body rhinitis in pigs. In a Swiss pig herd (n = 2 boars, 7 sows, 2 gilts, 18 finishing pigs, 30 fattening pigs, 54 suckling piglets), an outbreak of PCMV infection with high morbidity in all age categories, characterized by fever, anorexia, reduced general condition, respiratory signs and increased piglet mortality, was diagnosed by histopathology and molecular methods. Five fattening pigs (age ~ 17 weeks) additionally showed diarrhoea, not typical for PCMV infections, and one fattener had to be euthanized due to poor condition. Histopathologically, severe fibrinopurulent jejunoileitis with extensive atrophy and fusion of intestinal villi, loss of goblet cells and crypt abscesses associated to C. suis infection were present. In the liver, herpesvirus intranuclear inclusion bodies were observed and PCMV was confirmed by PCR/sequencing. No further infectious causes of diarrhoea (i.e. Rotavirus A; TGEV; PEDV; PCV-2; enterotoxigenic Escherichia coli or Lawsonia intracellularis) were detected in the euthanized fattener. Coproscopically, C. suis oocysts were identified in the faeces from further fatteners with diarrhoea. While C. suis usually produces disease only in suckling piglets, its association with severe intestinal lesions and diarrhoea in ~ 17-week-old fatteners was surprising. It is supposed that the underlying PCMV infection might have contributed to the presentation of clinical cystoisosporosis in fattening pigs. The interaction mechanisms between these two pathogens are unknown.

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A Porcine Cytomegalovirus (PCMV) outbreak was diagnosed in a Swiss pig herd

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Cystoisospora suis caused diarrhoea in 17 week-old fattening pigs co-infected with PCMV

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PCMV infection may produce immunosuppression in pigs

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PCMV may have contributed to presentation of clinical cystoisosporosis in fattening pigs

[Effect of herd health management on the prevalence of Postpartum Dysgalaktie Syndrome (PPDS) and the treatment incidence]

INTRODUCTION

The Postpartum Dysgalaktie Syndrome (PPDS) also known as metritis agalactia mastitis (MMA), is considered the most common disease of the sow after farrowing. The reasons for PPDS are multifactorial and are to be found in the areas of management and hygiene, feeding, water supply and animal specific factors such as body condition and age of the sows. In this study a veterinary herd health management was carried out in 28 pig farms with PPDS, with the aim to reduce the PPDS prevalence and animal treatment incidence (TI). In 20 of 28 problem farms the PPDS-prevalence could be decreased from 37.4% (± 21.8%) to 24.5% (± 14.1%). The TI was not significantly reduced. The most effective procedures to reduce the PPDS-prevalence were the use of a prepartal transition feed, optimizing the PPDSdiagnostic and the use of nonsteroidal antiinflammatory drugs (NSAID) and oxytocin in the PPDS-treatment.

[Influence of probiotics on the establishment of a competitive flora, as well as on antibiotic use and performance parameters in pig breeding farms]

INTRODUCTION

The aim of the present study was to investigate the effect of Probiotics in Progress (PIP) on the establishment of a competitive flora as well as on antibiotic use and losses of suckling piglets in pig breeding farms. The tested products were PIP AHC® and PIP AHS® produced by "Chrisal AG" in Lommel, Belgium. PIP`s are cleaning products containing Bacillus spores. According to the manufacturer's specifications, they are able to establish a steady non-pathogenic stable flora. In a field trial in 19 pig breeding farms, the use of PIP-products did not lead to any reduction of antibiotic use or improvement of fertility parameters, especially in relation to losses of suckling piglets. In addition, we compared the bacterial flora using PIP products with the flora under conventional management conditions in a farrowing pen by means of swab samples. The use of PIP-products did not lead to any significant effect on the pen flora. Only very few swab samples contained a majority of probiotic Bacillus spp.

Lethal Gastric Mucosal Necrosis due to Administration of Oral Ferrous Bisglycinate Chelate to Suckling Piglets

The oral application of a newly developed ferrous bisglycinate paste for suckling piglets at a dose of 180 mg/kg body weight led to increased death rates in 10% (n = 10) of Swiss test pig breeding farms (n = 100). Necropsy examination of suckling piglets (n = 12), selected randomly from the test farms with increased death rates, demonstrated severe gastric mucosal ulceration and necrosis. Due to the presence of crystalline iron surface coating within the gastric lesions, the iron was considered as the toxic principle and cause of death. To demonstrate the direct toxicity of ferrous bisglycinate, the paste was administered experimentally to a litter of suckling piglets (n = 11). Different time points (24, 48 and 72 h post partum) and doses (180 mg/kg and 360 mg/kg) were investigated. The manufacturer's recommended dose of 180 mg/kg corresponded to approximately 36 mg Fe/kg and to 6.4 % of the acute lethal dose₅₀ of oral iron in rats. In all piglets the lesions were reproduced and most severe at the earliest time point (24 h post partum) and with the highest applied dose (360 mg/kg). The lesions were in accordance with those described from oral iron intoxication in man, suggesting pigs as an ideal animal model for oral iron toxicity studies.

Experimental Toxoplasma gondii infections in pigs: Humoral immune response, estimation of specific IgG avidity and the challenges of reproducing vertical transmission in sows

Ten pregnant sows were experimentally inoculated per os with T. gondii in order to investigate vertical and galactogenic transmission of the parasite and the evolution and maturation of the specific IgG humoral response in the sows and piglets. Five seronegative sows received 10⁴T. gondii (CZ isolate clone H3) sporulated oocysts during late-pregnancy (Exp. 1), three sows received 10⁴ oocysts during mid-pregnancy (Exp. 2) and three sows from Exp. 1 (and two seronegative sows) were re-inoculated with 10⁵ oocysts during a further pregnancy (late-pregnancy) (Exp. 3). Besides, six 4.5 week-old piglets inoculated per os with 5×10³ oocysts were also included in the serological investigations. All animals seroconverted (PrioCHECK Toxoplasma Ab porcine ELISA, Prionics, Switzerland) by 2-3 weeks post inoculation (wpi) and remained seropositive for at least 38 weeks or until euthanasia. Four chronically infected sows from Exp. 1 and 2 were serologically monitored during a further pregnancy and no reactivation, but a decrease of the antibody levels was observed at farrowing (Exp. 4). In all experiments, the specific IgG-avidity was initially low, increased during the course of infection and after re-inoculations. An avidity index (AI) ≥40% could be used to rule out recent infections (<8 weeks) in most (15 of 16) animals. In some piglets (18.6% of 70) delivered by inoculated sows (Exp. 1 and 2), maternal antibodies were still detectable at 2 months (but not by 3 months) of age, with constant high avidity values, comparable to those of the dams at farrowing. In all experiments, the sows remained asymptomatic and delivered non-infected offspring at term. A total of 208 normal and 5 stillborn piglets delivered by the inoculated sows (Exp. 1-4) tested serologically negative before colostrum uptake. Placentas (n=88) from all sows and tissues (brain, liver, lung, heart, and masseter muscle) from 56 delivered piglets were analysed histopathologically and by real-time PCR for T. gondii with negative results. Colostrum and milk samples from all sows were negative by real-time PCR for T. gondii DNA. In addition, no seroconversion was observed in 16 piglets from seronegative dams that were transferred to infected dams one day after birth to detect a possible infection through colostrum or milk during the suckling period. Although vertical transmission of T. gondii was demonstrated in naturally infected pigs, many factors involved in the outcome of vertical transmission and congenital toxoplasmosis in pigs are still unknown.

Occurrence, clinical involvement and zoonotic potential of endoparasites infecting Swiss pigs

In order to estimate the diversity, clinical involvement and zoonotic potential of parasites in pigs submitted for diagnosis to the PathoPig project of the Swiss Federal Food Safety and Veterinary Office, faeces (n=125) from suckling piglets (n=39), weaners (n=60) and piglets beginning fattening (n=26) from 74 Swiss farms were examined by 3 coproscopical methods (i.e. sedimentation/zinc chloride-flotation; SAFC and Ziehl-Neelsen staining). Samples microscopically positive for Cryptosporidium were further tested by PCR/sequencing for species assessment. The most frequently detected parasite was Balantidium coli, a facultative pathogenic ciliate with zoonotic potential, in 5.1, 36.7 and 50.0% of suckling, weaners and fatteners and 43.2% of farms; however, no association with disease was observed. Isospora (syn. Cystoisospora) suis infections were detected in 13.3 and 11.1% of suckling piglets with and without diarrhoea, and in 10.0 and 13.3% of weaners and fatteners with diarrhoea, respectively, and were significant associated with emaciation. Cryptosporidium infections were detected in 10.3, 15.0 and 19.2% of sucklings, weaners and fatteners, respectively, and in 18.9% of the farms. Interestingly, two age-related species were identified: C. suis in younger piglets (2 to 6weeks) and C. scrofarum in older ones (6 to 17weeks). None of the pigs infected with C. scrofarum (n=8), but 3 of 4 piglets infected with C. suis (co-infection with I. suis in 2 cases) had diarrhoea. The zoonotic species C. parvum was not detected, nevertheless, sporadic cases of human infection with the porcine-adapted species have been reported. Ascaris suum, Trichuris suis and Strongylida were rarely detected (<4%) in all age categories.

The effect of the administration of three different antimicrobial premix formulations via the liquid feeding system on the occurrence of Enterobacteriaceae resistant to tetracycline in the liquid feed for pigs

INTRODUCTION

The oral group treatment is still a common procedure in swine production. This project studied the effect of the application of 3 different formulations of antimicrobial premixes (1. chlortetracycline, 2. chlortetracycline + sulfadimidine + tylosin, 3. sulfadimidine + sulfathiazole + trimethoprim) via the liquid feeding system on the occurrence of tetracycline-resistant Enterobacteriaceae (Ent-Tetr) in the liquid feed. 156 and 112 feed samples were collected between April and December 2015 in 13 case and 14 control farms, respectively. The 27 farms were randomly selected pig fattening farms located in different parts of Switzerland. The number of feed samples that contained Ent-Tetr as well as the number of Enterobacteriaceae resistant to tetracycline per sample was significantly higher in the case group than in the control group. The use of any of the 3 antimicrobial combinations turned out to be the main risk factor for the occurrence of Ent-Tetr in the liquid feed. Our results suggest that liquid feed containing antimicrobials is a reservoir of antimicrobial resistant bacteria in swine production.

[Evaluation of risk factors for Mastitis-Metritis-Agalactia in pig farms in Switzerland]

Mastitis-Metritis-Agalactia (MMA), also known as postpartum dysgalactia syndrome (PPDS) is the most important disease complex in sows after birth. The present study compared 30 MMA problem herds (over 12% of farrowing sows affected) with 30 control farms (less than 10% of farrowing sows affected) to identify risk factors and treatment incidence. Important risk factors identified were in gilts the integration into the herd after the first farrowing, in gestating sows firm fecal consistency as well as in lactating sows soiled troughs, a low flow rate (<2 liters per minute) in drinking nipples and a high prevalence of lameness. The treatment incidence was also significantly different between the two groups. The MMA prevalence could be reduced through optimization of husbandry, feeding and management, which could essentially diminish the use of antibiotics.

[Lung and pleural lesions before and after implementation of a national eradication program against enzootic pneumonia and actinobacillosis as well as changes of slaughter carcass organs in slaughter pigs in Switzerland]

In a representative cross-sectional study during 12 months of the years 2008/2009 in four abattoirs in Switzerland, lung and pleura lesions as well as lesions of slaughter carcasses and organs of 34 706 pigs were studied for frequency and type of macroscopic lesions. Of the 24276 examined pigs, 91.2% of the lungs, 94.4% of the heart and 95.5% of the livers showed no macroscopically visible lesions. Pigs that were produced for a label program had significantly less bronchopneumonia and pneumonia residuals, pleuritis and liver lesions due to echinococcosis. Pigs supervised by the Swiss Pig Health Service (SGD), showed significantly less bronchopneumonia and pneumonia residuals, diffuse pleuritis, pleuritis/pericarditis and milkspots compared to the non-SGD supervised farms. Thanks to the national eradication program for enzootic pneumonia (EP) and actinobacillosis, the health-status of lungs has been considerably improved and the prevalence of pleurisy decreased considerably. The results of this study indicate a good herd health in Swiss pig production.

Risk factors for oral antimicrobial consumption in Swiss fattening pig farms - a case-control study

Background

Antimicrobial consumption in veterinary medicine is of great importance. Increased awareness by the public and media has led to demands for decreased use of antimicrobials in pigs. This study aimed to identify risk factors for regular oral antimicrobial consumption in Swiss fattening pig farms, and to quantify the amount of antimicrobial active substances administered orally to pigs at the farm level.

Results

A case–control study was performed on 99 fattening farms between May 2014 and January 2015. Seventy-two case farms (with oral group treatment of antimicrobials in at least 50 % of pigs) and 27 control farms (with no regular oral group treatment) were visited once during the study. Data about potential risk factors and antimicrobial consumption were collected by questionnaire. Antimicrobial consumption was recorded and treatment incidence (TI) was calculated for all farms over a one year period. Sulphonamides and tetracyclines were the antimicrobials consumed in the greatest quantity. The median TI for oral antimicrobial use in the case group was 224.7. In the control group, the median TI was 0 for oral antimicrobial use, with values ranging from 0 to 140.1. In a multivariable regression model, seven risk factors associated with regular oral antimicrobial group treatment were identified: mixing pigs from different suppliers within the same pen, absence of a work protocol that ensures treating of healthy pigs before sick pigs, distance to next pig farm < 500 metres, external analysis of production parameters, no availability of dirty visitor boots, the farmer not working on other farms, and no application of homoeopathic agents.

Conclusions

The results of this study point out the importance of increasing farmers’ awareness of good farming practices and biosecurity. Important recommendations for decreasing oral antimicrobial consumption identified by this study include avoiding mixing pigs from different suppliers in the same pen and strictly handling sick pigs after healthy ones. Improvements in these areas could enhance the overall health of pigs and thereby reduce the consumption of antimicrobials on pig farms.

Latent porcine circovirus type 2-infected domestic pigs: A potential infection model for the effective development of vaccines against latent or chronic virus induced diseases

Until recently, knowledge of the pathogenicity of Circoviridae and Anelloviridae family members was limited. Our previous discoveries provided clues toward resolving this issue based on studies of the latent nature of porcine circovirus type 2 (PCV2) genotype group members. We developed a conventional pig infection model that indicated that weaners already harbored latent PCV2 infection in the thymus, which enabled the viruses to specifically modulate the maturation of T-helper cells. This finding raised the possibility that the thymi of normal fetuses were already infected with PCV2. The present findings further substantiate our hypothesis that PCV2 masquerades as the host by infecting fetuses before they acquire immune-competence. We provide the first demonstration that all domestic pig fetuses preferentially harbor latent PCV2-infected cells in their thymi. These PCV2-infected cells are different from thymocytes and are located in the medulla of the fetal thymus. These latent PCV2-infected cells in fetuses are found at the same location and share characteristics with the infected cells observed in adolescent pigs. Moreover, fetuses also harbor these infected cells in other lymph system organs. We provide the first demonstration that the fetal thymus virus pools are minimally affected by sow vaccination, highlighting the immune-privileged character of this organ. Furthermore, we found a striking reduction in virus-infected cells in the fetal spleen and an increase in PCV2-infected cells in the fetal intestine of anti-PCV2-vaccinated mothers. These data indicate that specific immune response interactions occur between mothers and their progeny that are not dependent on the humoral immunity of the mother and cannot be attributed to the rudimentary humoral responses of the fetuses because these pig fetuses do not have any PCV2-specific antibodies. These shifts in our understanding of the PCV2-infected cell pool will lead to different avenues in the search for effective vaccination strategies against latent and chronic pathogens.

Longitudinal study on the colonisation and transmission of methicillin-resistant Staphylococcus aureus in pig farms

Knowledge about the dynamics of methicillin-resistant Staphylococcus aureus (MRSA) in pigs lacks detail at the level of individual animal. The aim of our study was therefore to determine the colonisation status of MRSA in individual pigs from birth to slaughter in order to gain a better understanding of substantial factors involved in transmission. Two farrow-to-finish and two grow-to-finish herds were included in the study. A total of 1728 nasal swabs from 390 pigs and 592 environmental wipes were collected at 11 different time points. Intermittent colonisation throughout the entire production cycle was conspicuous in the tracking of MRSA in individual pigs. Almost all pigs from a MRSA-positive herd changed MRSA status several times, which implies that pigs are transiently rather than permanently colonised. We highly recommend the definition of MRSA status at herd level rather that at the level of the individual pig when considering prevention measures against MRSA. Therefore, to avoid the further spread of MRSA in countries with moderate prevalence, such as in Switzerland, defining farms as MRSA positive or MRSA negative and allowing the trade of pigs only within herds of the same status seems feasible. This will also be important for combating the further dissemination of livestock-associated (LA)-MRSA into healthcare facilities and the community via humans who have close contact with animals.

Prevalence of Chlamydial Infections in Fattening Pigs and Their Influencing Factors

Chlamydial infections in pigs are associated with respiratory disease, diarrhea, conjunctivitis and other pathologies. The aim of this study was to define the prevalence of Chlamydiaceae in Swiss fattening pigs by applying sensitive and specific detection methods and to correlate prior antibiotic treatment and farm related factors with differences in prevalence. Conjunctival and fecal swabs were collected from 636 pigs in 29 Swiss fattening pig farms with and without antibiotic treatment, at the beginning and the end of the fattening period. The swabs were screened by real-time PCR for Chlamydiaceae. For the chlamydial detection and species-identification, a DNA-microarray analysis was performed. All farms were positive for Chlamydiaceae with 94.3 and 92.0% prevalence in fecal swabs as well as 45.9 and 32.6% in conjunctival swabs at the first and second time points, respectively. Antibiotic treatment could not clear the infection on herd level. Potential contact with wild boars was a significant risk factor, while hygiene criteria did not influence chlamydial prevalence. A correlation of chlamydial positivity to diarrhea, but not to conjunctivitis was evident. Chlamydia suis was the predominant species. Mixed infections with C. suis and C. pecorum were common, with a substantial increase in C. pecorum positivity at the end of the fattening period, and this finding was associated with ruminant contact. C. abortus was detected in one conjunctival swab. In this study, C. suis inhabited the intestinal tract of nearly all examined pigs, implying a long-term infection. C. pecorum was also common and might be transmitted to pigs by ruminants.