The apparent prevalence of skin lesions suspected to be human-inflicted in Danish finishing pigs at slaughter

Skin lesions on pigs inflicted by humans compromise animal welfare and are the subject of increased public and political attention in Denmark. Systematic surveillance of such skin lesions was enforced in April 2010 at all Danish pig abattoirs, through the recording of meat inspection Code 904 for the presence of skin lesions suspected to be human inflicted. The objectives of the present study were to (a) estimate the apparent prevalence of Code 904s at the pig and herd owner level; (b) characterise the distribution of deliveries with pigs demonstrating a Code 904; (c) characterise the distribution of herd owners with repeated Code 904 recordings; and (d) determine the developments in Code 904 prevalence over time in Danish finishing pigs in the period from May 1, 2010 to September 30, 2013.     

Group-level effects of breed and sire on diseases, and influence of diseases on performance of pigs in Danish test stations

The epidemiologies of the most common diseases diagnosed in pigs at the Danish pig-breeding test stations were studied with special reference to possible genetic predisposition. The population under study comprised 9084 test pigs (corresponding to 3028 test groups) housed at nine test stations from September 1983 to September 1984. There were substantial differences between the four breeds in the study (Landrace, Yorkshire, Duroc and Hampshire) with the white breeds having higher clinical incidences of respiratory diseases and culling rates than the coloured ones. In only one of nine analyses was a significant sire effect found. However, significant differences were found between breeding centres of origin. There was a negative influence of clinical diseases on daily gain and feed conversion. Classifying respiratory disease in an ‘early’ form (at least one pig in the group was treated during the first 45 days of the test period) and a ‘late’ form (treatments were given after this period) showed that late infections resulted in a higher reduction of performance than early infections did. There were no associations between pathological findings at slaughter and growth rate.     

Survey on Salmonella prevalence in slaughter pigs from Saskatchewan

A study on slaughter pigs from Saskatchewan detected Salmonella organisms in 12.5% and 5.2% of cecal content and ileocaecal lymph node samples, respectively. Cecal content prevalence was associated with larger farms and longer lairage periods. Antimicrobial resistance was detected in 41.5% of the isolates. Salmonella Enteritidis was the second most prevalent serotype.     

The correlation between Salmonella serology and isolation of Salmonella in Danish pigs at slaughter

In Denmark, a serological Salmonella surveillance programme in finishing pig herds has been in place since 1995. The programme was founded on data from experimental studies, which demonstrated a strong association between Salmonella serology and the prevalence of these bacteria. The current study was carried out in three Danish abattoirs to evaluate the correlation under field conditions. A total of 160 Danish finishing pig herds were included. Seven out of these were examined twice, yielding a total of 167 observations. The herds were selected according to their herd serology based on data from the national surveillance. From each herd, samples were taken from 10 finishers at slaughter. The prevalence of Salmonella bacteria was measured at four sites: (1) caecal-content; (2) carcass surface; (3) pharynx; and (4) caecal lymph nodes. A logistic regression model was constructed for each sampling site. Abattoir, sanitary slaughter and herd seroprevalence were used as explanatory variables. The results demonstrated that there was a strong association between herd serology and the prevalence of Salmonella bacteria measured at three of the sampling sites: caecal-content, pharynx, and carcass surface. For these sites, the odds for being culture-positive for Salmonella varied from 1.3 to 1.5 for each increase of 10% in herd serology (P < 0.0001). For caecal lymph nodes, however, no linear association was found.     

Association between growth indicators and volume of lesions in lungs from pigs at slaughter.

Conflicting findings exist among studies on the effect of pneumonia on growth in pigs. We determined the extent of pneumonia in market-weight pigs by use of an objective, volumetric method and linear regression analyses of mean daily gain and days-to-slaughter weight on the percentage of pneumonic lung. In a range of extent of pneumonia between 1.33 and 70.44%, a 10% increase in the volume of pneumonic lung was associated with a decrease in mean daily gain by 41.1 g and a 16.7-day increase in number of days to a slaughter weight of 104.5 kg.     

Herd prevalence of Salmonella enterica infections in Danish slaughter pigs determined by microbiological testing

As a part of a nationwide programme to survey and control salmonella in pig herds, a microbiological survey of 1363 pig herds was performed in Denmark. A total of 13 468 slaughter pigs were examined at slaughter by culture of 5 g of caecal contents. Overall, 30 different serotypes of Salmonella enterica were isolated from 832 pigs (6.2%). The predominant serotype was S. Typhimurium, comprising 536 (64.4%) of the isolates. Four hundred and forty-eight isolates of S. Typhimurium were examined by phage typing, resulting in detection of 17 different phage types (definitive types, DT) with DT12 being the most frequent (49.1%).

Salmonella enterica was found in 302 herds (22.2%), S. Typhimurium was found in 61.1% of these. 279 (23.1%) large herds (producing more than 2600 slaughter pigs per year) were found to be salmonella positive compared with 23 (14.7 %) small herds (annual production of 500 to 550 slaughter pigs). Practical constraints in the study design did not allow for a firm conclusion on the interplay among herd size, geographical location and occurrence of salmonella.

In 284 of 302 infected herds (94.0%) only one serotype was detected. Infections with two different serovars were seen in 18 herds (6.0%).     

Interrelations between diseases and effects of treatment procedures on some production parameters at Danish pig-breeding test stations

The epidemiologies of the most common diseases diagnosed in pigs at the Danish pig-breeding test stations were studied. The population under study comprised 9 084 test pigs housed at nine test stations from September 1983 to September 1984. At some stations the animals were treated for respiratory disease at an early stage, while at others the animals were treated late in the testing period. Great differences among stations were found in the intensity of treatment expressed as average number of treatments per test pig (total incidence), average number of treatment periods per treated pig (repeated treatments) and average number of treated pigs per treated group (prophylactic treatment of pen mates). The time at which the treatment started and the intensity of treatment both had significant effects on the culling rate and on the average growth rate at the station level. Associations between clinical respiratory disease, diarrhoea and other diseases were postive in the specific-pathogen-free (SPF) system, but differed from station to station in the conventional health system. Higher prevalences of pleuritic and pneumonic lesions were found at routine meat inspection in pigs treated for respiratory disease that in non-treated pigs. The time between last treatment for respiratory disease and slaughter influenced the meat inspection findings (suggesting that pneumonic lesions, in particular, were resolved with time).     

Serum-haptoglobin concentration in Danish slaughter pigs of different health status

A cross-sectional study was conducted with 617 finishing pigs aged 10–25 weeks in 11 commercial herds of different health statuses as defined by the Danish monitoring program for specific-pathogen-free (SPF) herds. A standard clinical examination was performed and a blood sample was obtained from each pig for determination of haptoglobin concentration in serum.

Pigs aged 10–14, 15–19 and 20–25 weeks in conventional herds had higher haptoglobin concentrations than high-health SPF (SPF-x) pigs of the same age. There was no significant difference between SPF-x pigs of different ages. Conventional pigs aged 15–19 and 20–25 weeks had higher haptoglobin concentrations than conventional pigs aged 10–14 weeks. Herd influenced the haptoglobin concentration. Lame pigs and pigs with tail or ear bite had elevated haptoglobin concentrations. No significant effect of respiratory symptoms or umbilical hernia was found.     

Relationships between tail biting in pigs and disease lesions and condemnations at slaughter

Two matched case-control studies were performed at an abattoir with a capacity of 780 pigs per hour, each study using the approximately 7000 pigs slaughtered on one day. In the first study, the severity of tail biting and pneumonia were recorded in pigs with bitten or intact tails. In the second study, the tail score, sex, and the presence of pleuritis, externally visible abscesses and trimming were recorded in pigs with bitten or intact tails. In study 1, there was no significant association between the tail score and the percentage of lung tissue affected by lesions typical of enzootic pneumonia, but there was a significant association between the severity of tail biting and the prevalence of lungs with abscesses and/or pleuritic lesions (P<0.0001). In study 2, there were significant associations between the severity of tail biting, and the prevalence of external carcase abscesses and carcase trimming; the carcases of castrated males had evidence of tail biting more frequently than the carcases of females (P<0.05).     

Study of methicillin resistant Staphylococcus aureus (MRSA) in Danish pigs at slaughter and in imported retail meat reveals a novel MRSA type in slaughter pigs

Methicillin-resistant Staphylococcus aureus (MRSA), especially CC398, have emerged in livestock worldwide. We investigated the occurrence of MRSA in pigs at slaughter and in retail meat. During 2009, nasal swabs (n=789) were taken from pigs at slaughter. Moreover, 866 meat samples [Danish: pork (153), broiler meat (121), beef (142) and; imported: pork (173), broiler meat (193), and beef (84)] were randomly collected in retail stores and outlets. MRSA was isolated from nasal swabs or from meat samples after preenrichment (Mueller Hinton broth with 6.5% NaCl), selective enrichment (tryptone soya broth with 4 mg/L cefoxitine and 75 mg/L aztreonam) and selective plating on Brilliance Chromogenic MRSA agar. The presence of mecA was confirmed by PCR and the MRSA isolates were spa typed. Novel MRSA spa types were characterized by MLST, PFGE and SCCmec typing. Thirteen percent (101/789) of the pigs had MRSA. Based on spa types 93% corresponded to CC398 (spa t011, t034, t1451, t2876, t2974), 4% to CC30 (t1333) and one isolate to CC1 (t0127). The spa type t1333 (CC30), which is common among methicillin susceptible S. aureus (MSSA) from pigs in Denmark, contained a SCCmec cassette type V and czrC zinc resistance gene. Imported broiler meat had the highest occurrence (18%) of MRSA, followed by imported pork (7.5%) and Danish pork (4.6%). MRSA ST398 was found for the first time in Danish beef (1.4%). The finding of MRSA CC30 (spa t1333) suggest possible spread of the SCCmec cassette normally associated with ST398 into another S. aureus lineage common in pigs.     

Bacterial pathogens associated with lung lesions in slaughter pigs from 125 herds

Relationships between macroscopic lesions and Polymerase Chain Reaction (PCR) detection of Mycoplasma hyopneumoniae (Mhp), Pasteurella multocida (Pm), Actinobacillus pleuropneumoniae (App), Haemophilus parasuis (Hps) and Streptococcus suis (Ssuis) of the lungs of 3731 slaughter pigs from 125 herds were assessed in France. Pneumonia and pleuritis were the most frequent lesions (69.3% and 15% of the lungs, respectively). Mhp, Pm, App, Ssuis and Hps were detected in 69.3%, 36.9%, 20.7%, 6.4% and 0.99% of the lungs, respectively. Mhp and Pm were associated with pneumonia at both the pig and herd levels. Pleuritis was not associated with any pathogen at the pig level, but was associated with a high percentage of pigs PCR-positive for App at the herd level. Measures focused on control of Mhp, Pm and App should significantly reduce the occurrence of both pneumonia and pleuritis.     

Prevalence of pleurisy in pigs at slaughter

The mean (+/- sd) batch prevalence of pleura stripping of finished pigs going for slaughter in four abattoirs in eastern England was 0.15 +/- 0.04, and the average batch proportion of lungs totally condemned was 0.23 +/- 0.05. There was a significant positive correlation between the number of carcases requiring total lung condemnation and the number of carcases requiring pleura stripping. There was no significant differences between the type of producer, the herd size or the mean batch live weight and the prevalence of pleurisy, either within individual abattoirs or combining the data from the four abattoirs. There was considerable variation in the batch prevalence of pleurisy from the same producer, indicating the need to monitor a number of batches in order to determine the prevalence of pleurisy on a farm.     

A cross-sectional study of risk factors associated with pulmonary lesions in pigs at slaughter

A cross-sectional study was conducted to identify herd-level factors that may influence the prevalence and severity of macroscopically visible pulmonary lesions in pigs at slaughter. Data were collected following abattoir inspection of 50 randomly-selected batches of 6335 pigs and by interviewing the producers. Macroscopic lung lesions were identified and scored semi-quantitatively in ?80 pigs/herd and the prevalence of pleuritis and pneumonia was 20.76% and 23.85%, respectively. Following multivariable analysis, the seroprevalence of Actinobacillus pleuropneumoniae (P < 0.001) and Mycoplasma hyopneumoniae (P = 0.018) and the number of pigs/nursery pen (P = 0.023) were positively associated, whereas average weaning age was negatively associated (P = 0.001) with the pleuritis score. Risk factors associated with a higher prevalence of pneumonia were the presence of pleuritis (P = 0.001) and the frequent purchasing of pigs (P = 0.020). The findings of this study indicate that the prevalence of pleuritis and pneumonia remains high in Belgium and management factors are central to disease control.     

Prevalence of gastric lesions in the pars proventricularis in finishing pigs at slaughter in Switzerland

A cross-sectional study was conducted at two large abattoirs in the winter 2003/04 to determine the prevalence of gastric lesions in Swiss finishing pigs. The stomachs of 1897 pigs from 107 slaughter groups were examined for macroscopic epithelial lesion of the pars proventricularis. Severe hyperceratosis, erosion, ulceration and constriction at the transition between oesophagus and stomach were described as gastric lesions. Lesions were observed in 36% of all animals, with slaughter group prevalence ranging from 0% to 94%. Ulceration or constriction was present in four percent of the examined pigs. Associations between gastric lesions, farm management data, and data obtained at ante and post mortem examinations conducted at the slaughterhouse were analysed. A significantly higher prevalence of gastric lesions was found in pigs originating from conventional housing systems compared to pigs raised on farms with 'animal-friendly' housing systems providing straw bedding and outdoor exercise to pigs. In addition, significantly higher prevalence was observed in pigs originating from herds with clinical signs of tail biting and peritarsitis.     

The prevalence of anti-yersinia outer protein antibodies in Bavarian slaughter pigs

The aim of the present study was to provide current data on the prevalence of anti-Yersinia-antibodies in Bavarian slaughtering pigs. The recomBlot Westernblot assay based on five recombinantly produced Yersinia Outer Proteins (YopD, YopE, YopH, YopM, V-antigen) is well evaluated for the use in the diagnosis of human yersiniosis and proved to be also a valuable tool for the detection of porcine antibodies. 965 out of 1002 meat juice samples collected in 53 Bavarian pig farms contained anti-Yop/V-Ag-antibodies. Only blots with three or more detectable signals were considered as positive. On the basis of these results a possible previous history of Yersinia infection was detected in 45.4% of the pigs and all of the pig farms. The high prevalence of anti-Yersinia-antibodies found in this investigation demonstrates the need for further epidemiological surveillance and animal studies to assess consumers' endangering.     

Non-infectious factors associated with macroscopic and microscopic lung lesions in slaughter pigs from farrow-to-finish herds

A cross-sectional epidemiological study was conducted in 150 randomly selected farrow-to-finish herds to investigate which non-infectious factors might act as risk indicators for the prevalence and severity of macroscopic and microscopic lung lesions in slaughter pigs. Data were collected during herd visits through inspections of the pigs and through interviews with the farmers. Macroscopic lung lesions of pneumonia and pleuritis were recorded at slaughter from 25 pigs per herd, and microscopic lung lesions of lymphohistiocytic infiltration were recorded from 10 pigs per herd. The median herd level prevalences were 24 per cent for pneumonia, 16 per cent for pleuritis and 60 per cent for lymphohistiocytic infiltration. Pneumonia lesions were negatively associated with pleuritis lesions and positively associated with lymphohistiocytic infiltration. Pleuritis lesions were negatively associated with lymphohistiocytic infiltration. The prevalence and the severity of pneumonia lesions were increased by a high frequency of purchasing gilts and by a slaughter date in January to February. The presence of a growing unit also increased the severity of pneumonia. The prevalence and the severity of pleuritis lesions were higher when there were more pig herds in the municipality, and when there were poor biosecurity measures, and their prevalence was increased by a slaughter date in January to February, and their severity by a slaughter date in March to April. An increase in the airspace stocking density in the finishing unit also increased the prevalence of pleuritis. The prevalence and the severity of lymphohistiocytic infiltration in the lung tissue were higher in herds purchasing gilts. Pigs raised in pens with slatted floors were also at higher risk of more severe lesions of lymphohistiocytic infiltration.     

Association between lean meat percentage and average daily weight gain in Danish slaughter pigs

Danish pigs that are within optimal weight limits and have a high lean meat percentage (LMP) obtain the best prices at slaughter. Another reason to consider the variation in LMP is the assumed association between LMP and average daily weight gain (ADG) at the individual level. The aim of this study was to test whether high ADG was associated with low LMP and vice versa. A cohort of 99 pigs from a conventional Danish herd was followed from 30kg to slaughter. The data included days in the herd, start- and end-weights, calculated ADG and LMP, reported from the abattoir. The study also included existing data from 13,057 boars from a Danish boar test station. The results of the study demonstrated a significant negative association between LMP and ADG: Pearson's correlation coefficient (r)=-0.42 (95% CI: -0.57; -0.24) (p<0.0001) for the cohort and r=-0.42 (95% CI: -0.48; -0.36) (p<0.0001) for the boars.     

Problems of interpretation of ileal lesions in New Zealand slaughter pigs

The term proliferative enteritis (PE) is a collective one used to describe a group of related diseases characterised by adenomatous intestinal epithelium frequently seen to contain intra-cellular campylobacter-like organisms. It embraces four related disease syndromes, porcine intestinal adenomatosis (PIA), necrotic enteritis (NE). regional ileitis and proliferative haemorrhagic enteropathy (PHE), all affecting mainly the terminal ileum.     

Retrospective detection of methicillin resistant and susceptible Staphylococcus aureus ST398 in Danish slaughter pigs

This retrospective study documents the first detection in Danish pigs of methicillin resistant and susceptible variants of the Staphylococcus aureus lineage ST398, which was previously described among pigs, pig farmers and veterinary staff in The Netherlands as well as in human patients and infected animals in Europe. Ten out of 100 pigs tested were shown to carry ST398 in the nasal cavity and two out of three farms tested were positive. The 10 porcine ST398 isolates had spa type t034 (n=9) and t1793 (n=1), and were resistant to erythromycin, clindamycin and tetracycline in addition to penicillin. The detection of ST398 in Danish pigs suggests that this new emerging zoonotic bacterium is rapidly spreading in the pig population in Europe.