Questionnaire survey of proliferative enteropathy on British pig farms

Slaughterhouse Visual and Palpation Method for Estimating the Economic Damage of Porcine Proliferative Enteropathy (PPE)

BACKGROUND

Ileitis is a wasting disease of pigs. Clinical symptoms are diarrhea in growing pigs, wasting and reduced performance. Ileitis is ubiquitous in pig producing countries all around the world. It is estimated that the economic losses caused by the disease are USD 4.65 per fattening pig, and American pig farmers lose USD 56.1 million annually. It has become necessary to develop a slaughterhouse ileitis monitoring method that is simple, feasible to perform at modern slaughter lines, leads to immediate results and is cost effective. The practical experiences of applying the method are presented below.

METHODS

Our studies were performed on pig herds and slaughterhouses in Central European countries (Hungary, Romania, Poland, Croatia, and Slovakia). Experiences were evaluated based on visual and palpation. The results of our investigations were evaluated by a scoring method. Authors made histological and immunohistochemical examinations of investigated ileums. The hypothetic economic losses due to the disease in each farm were determined by estimating the loss of profit according to Holtkamp's presentation in 2019.

RESULTS

The essentials of the method we have developed are: it can be performed during slaughterhouse processing, it does not interfere with or make it impossible to carry out normal technological processes, and the results of the procedure are correlated with the results of other laboratory diagnostic tests for ileitis (histology, immunohistochemistry, herd serology, fecal PCR). It is noteworthy that the results of the method can be used to immediately estimate the impact of Lawsonia intracellularis infection on the performance of the herd from which the slaughter animals come.

CONCLUSION

Using the results of the slaughtered pigs' visual and tactile examination at the slaughterhouse, the magnitude of the loss caused by Lawsonia intracellularis infection can be estimated quickly and accurately, and the return on investment of the strategy to be applied can be accurately planned.

Correlation of Lawsonia intracellularis positivity in quantitative PCR and herd factors in European pig herds

BACKGROUND

Lawsonia intracellularis is causing diarrhea, poor growth and sudden death in pigs. It can be found in most pig populations leading to large economic losses worldwide. Many potential risk factors for the occurrence of disease or seropositivity have been described. The current study therefore focused on herd characteristics in European countries associated with direct detection of the pathogen determined by quantitative polymerase chain reaction.

RESULTS

A median number of less than 30 nursery pigs per pen was correlated to less positive nursery pigs (p < 0.01) and generally less samples positive per herd (p < 0.05) as well as a lower median of genome equivalents determined per herd (p < 0.05). Routine use of zinc oxide at/ around weaning, which was mentioned by 41.0% of all farmers, was correlated to higher number of positive nursery pigs (p < 0.01) as well as higher median genome equivalents determined per herd (p < 0.05). Slatted flooring of more than 78.0% of the surface in nursery units was correlated to lower number of positive animals (p < 0.05) and a lower median of genome equivalents per herd (p < 0.05). A weight of more than 7.8 kg at weaning was correlated to a higher number of positive growing pigs (p < 0.05) as well as general higher number of positive samples/ herd (p < 0.01).

CONCLUSIONS

Weaning and subsequent accommodation of nursery pigs seem to be of particular importance in prevention of infection with Lawsonia intracellularis and the spread of the pathogen within the herd.

Herd-level risk factors for antimicrobial demanding gastrointestinal diseases in Danish herds with finisher pigs: A register-based study

Endemic gastrointestinal (GI) diseases have a substantial negative impact on pig production, because, when present, they reduce animal welfare, productivity and generate high antimicrobial (AM) demand. In Danish legislation, AM can be prescribed only for therapeutic purposes. The objective of the study was to estimate the association between herd-level risk factors and the amount of AM use (AMU) in connection with GI diseases in finisher herds. We conducted a register-based cross-sectional study with repeated measurements from 2004 to 2007. Data were extracted from databases in the Danish Register of Veterinary Medicine, the Central Husbandry Register and the Danish Agriculture and Food Council. In total, 3192 pig herds with 26,973 records (quarters with prescriptions) were included. The outcome was presented as average AM use (measured as Animal Daily Dosage) for GI diseases per finishing pig per quarter per herd. Three potential herd-level risk factors were evaluated: herd size (number of finishers delivered for slaughter); herd health status (herds in the Specific Pathogen Free (SPF) System, conventional herds); and herd type (herds including only finishers, integrated herds). Data were analyzed using general linear mixed models with repeated measurements. Smaller herds had a larger AMU per finisher than larger herds. Integrated herds had lower AMU as compared with herds with only finishers. Herds within the SPF System had a larger decrease in AMU with increasing herd size compared to conventional herds. Significant regional differences in AMU were seen. Additionally, the results showed that other herd factors and veterinarians were more influential than the investigated herd risk factors. This illustrates the difficulties of characterising AM-demanding GI diseases in herds by the use of register data only.

Monitoring of Lawsonia intracellularis in breeding herd gilts

In modern pig production, proliferative enteropathy is a common cause of diarrhoea and poor growth in young animals. This study aimed to determine the possible spread of Lawsonia intracellularis through the sale of replacement gilts and the possibility to protect the herds by adequate biosecurity measures. This was achieved by repeated sampling of 50 gilts in an infected multiplying herd, from the last day in the farrowing pen and until sale. Further, 60 gilts sold from this herd were tested during their stay in quarantine in a recipient herd. To confirm freedom from infection, 100 growing pigs in the recipient herd were also tested. Individual faecal (n=748) and blood (n=728) samples were analysed by PCR and ELISA, respectively. Transmission of L. intracellularis from the sows to their offspring was not demonstrated. However, the possible transmission between herds by replacement gilts was demonstrated. Peak shedding occurred at 12 and 15 weeks of age, and single animals were also PCR-positive at 24-36 weeks of age in the multiplying herd and in the quarantine in the recipient herd. Further, the possible occurrence of chronically infected carrier animals was suggested. Although L. intracellularis is widely spread, it appears possible to avoid the transmission between herds by employing adequate biosecurity measures. Thus, it would be advisable to establish herd profiles in breeding herds to avoid the selling of infected animals as well as to establish the health status of the recipient herd. Further, the health status of the recipient herds should be known.

Porcine proliferative enteropathy: an important disease with questions remaining to be solved

Proliferative enteropathy caused by the intracellular bacterium Lawsonia intracellularis is an endemic disease with high herd prevalences reported worldwide. The infection has a considerable impact on pig production and herd economics and, with the development of new diagnostic techniques, L. intracellularis is being identified in an increasing number of pig herds and a wider range of species. This paper reviews current knowledge of the disease, with a focus on the epidemiology in pigs. The prevalence of infection, transmission, predisposing factors, microbial features, pathogenesis, clinical signs, diagnosis, treatment and control are discussed. The disease is mainly controlled by antibiotic treatment and vaccination at herd level. In the development of effective measures to prevent the spread of the infection, increased knowledge of the transmission and persistence of the microorganism are crucial.

Risk factors for post-weaning diarrhoea on piglet producing farms in Finland

Background

Post-weaning diarrhoea (PWD) is a significant gastrointestinal disease in pigs. It is considered a multifactorial disease associated with proliferation of enterotoxigenic Escherichia coli in the intestinal tract of affected pigs. The aim of this study was to analyse risk factors related to the occurrence of PWD on Finnish piglet producing farms.

Methods

The data of a follow-up study of 73 conventional piglet producing farms was used in the case-control study. The selection of the 41 PWD case and 28 control farms was based on the use of antimicrobials for treating diarrhoea in weaned pigs and the answers related to the occurrence of diarrhoea after weaning in the questionnaire. Four intermediate farms were excluded from the statistical analysis.

Altogether 39 factors related to herd characteristics, weaner pig management and pig health were studied. The median number of sows was 59.0 (IQR = 44.0; 74.5) and 52.5 (IQR = 36.8; 61.5) on the case and the control farms, respectively.

The significances of the univariable associations between the explanatory variables and the outcome variable were tested, and in the multivariate analysis quasibinomial generalized linear models were applied.

Results

An increased risk of PWD was associated with the regimen of twice a day feeding and feed restriction after weaning (P = 0.02; compared to feeding three or more meals a day or the use of ad libitum feeding) and with a higher number of sows on the farm (P = 0.02; risk increasing with increasing number of sows). Automatic temperature control was associated with a decreased risk of PWD (P = 0.03; compared to manual temperature control).

Conclusion

Twice a day feeding of newly-weaned pigs should be avoided if the amount of feed given is restricted. Variation in ambient temperature should be minimized in housing of newly-weaned pigs and this can be achieved by using automatic temperature control. With increasing number of sows in the herds the risk of PWD increases and more attention should be paid to prevention of post-weaning diarrhoea.

Seroprevalence of Lawsonia intracellularis in different swine populations in 3 provinces in Canada

Porcine proliferative enteropathy caused by Lawsonia intracellularis is an important enteric disease in swine throughout the world. Information regarding the distribution of this pathogen in Canadian swine herds would be beneficial for the creation of control protocols. Pigs from Ontario, Quebec, and Alberta were tested by using an indirect immunofluorescence assay for antibodies to L. intracellularis. Pig seroprevalence was calculated as the proportion of pigs positive from total pigs tested in the targeted population. Seroprevalence (+/- standard error [s(x)]) in market hogs in Ontario from farrow-finish (FF) farms and finishing (FIN) farms were significantly different at 77% (s(x) = 7%) and 29% (s(x) = 15%), respectively. Seroprevalence for sows and gilts in FF and farrowing and nursery (FAR + NUR) farms in Ontario were 90% (s(x) = 3%) and 93% (s(x) = 6%), respectively. Seroprevalence in breeding females in Quebec from FF and FAR farms was 82% (s(x) = 5%) and 87% (s(x) = 3%), respectively. Seroprevalence (57%, s(x) = 8%) in finishing pigs in Alberta from FF farms was significantly different from that of multisite (MS) farms and FIN farms, 6% (s(x) = 6%) and 9% (s(x) = 5%), respectively. Lawsonia intracellularis appears to be widespread in Canada and the seroprevalence on FF farms is higher than that on FIN and MS farms, possibly due to the presence of breeding females or management differences.

Lawsonia intracellularis infection in the large intestines of pigs

In this study we examined the proliferative enteropathy, caused by the obligate intracellular bacterium Lawsonia intracellularis, in colon of naturally infected pigs, using immunohistochemistry, in situ hybridisation and scanning confocal laser microscopy. When 396 pigs submitted for routine laboratory examination were investigated, large intestinal gross lesions were seen in 93, including 74 cases of L. intracellularis colitis (proliferative enteropathy). Fifty-one pigs without recorded colonic gross lesions revealed L. intracellularis colitis microscopically. In four cases, L. intracellularis was only revealed in colon. Fifty-seven pigs were positive for L. intracellularis in the small intestines only. Thus, the overall prevalence of colonic infection in L. intracellularis-positive animals was as high as 69% (125 out of 182). In comparison, the large intestinal pathogens Brachyspira hyodysenteriae and Salmonella enterica were only isolated from 5 and 4 of the 93 cases, respectively. Morphologically, an unforeseen severe involvement of the subepithelial mucosa with multiple L. intracellularis found free and within large macrophages was observed in areas with acute infection. The distribution of whole L. intracellularis organisms was confirmed by in situ hybridisation and scanning confocal laser microscopy. The significance and possible role of subepithelial infection in the proliferative enteropathy is discussed. In conclusion, the study shows that L. intracellularis is a prevalent cause of naturally acquired colitis in pigs.

Lawsonia intracellularis Proliferative Enteropathy in a Filly

Proliferative enteropathy (PE) caused by the obligate intracellular bacterium Lawsonia intracellularis is a disease of high economic impact in swine worldwide. In most other species the disease occurs as a sporadic infection. This paper reports a PE caused by L. intracellularis in a 9-month-old Pura Raza Española filly with a history of profuse diarrhoea. Pathological lesions consisted of a severe proliferative enteritis associated with argyrophilic bacteria in the apical cytoplasm of proliferating crypt epithelium. Characteristic PCR products confirmed the presumptive diagnosis of L. intracellularis infection. To our knowledge this is the first report of PE in a horse in Europe caused by L. intracellularis.

The effect of antimicrobial growth promoter withdrawal on the health of weaned pigs in Finland

The use of the antimicrobial growth promoters (AGPs) carbadox and olaquindox has been banned in the European Union (EU) since September 1999. We studied the effects of the withdrawal on the health of weaned piglets on two types of piglet-producing farms (farrowing herds and farrow-to-finish herds) from the different regions of Finland. Farms with no major problems with post-weaning diarrhoea were selected for the study to better evaluate the effect of AGPs alone. Data on production, medication and incidence of diarrhoea were collected from 73 farms during 1 year after the withdrawal. On 29 of these farms, the data collection began 4 months before the withdrawal. The health management of the pigs is considered good in Finland, and special attention has been paid to improve the husbandry practices and management of the farms. Eighty-two percent of the farms in the study were free of both Mycoplasma hyopneumoniae and Sarcoptes scabiei infection. Brachyspira hyodysenteriae infection was not detected in any of the farms. The median number of sows in the herds was 56.0 (IQR=43.0; 72.5) in 2000. The level of antimicrobial use in each herd was classified as low, moderate and high when the percentage of weaned pigs treated for diarrhoea during a 4-month period was 0-5%, 6-19% and > or =20%, respectively. Only on four herds (14%), there was an increase in the level of antibiotic use after the AGP withdrawal, when seasonally corresponding 4-month periods were compared. Fourty-one percent of these 29 farms were categorized as low users of antimicrobials, 38% as moderate users and 21% as high users. The level of antimicrobial use for treatment of diarrhoea after weaning (and the incidence of diarrhoea in weaned piglets) did not increase significantly after the withdrawal of AGPs from weaner feeds according to farmers' evaluations. In this study, the Escherichia coli infection was the most-common cause of diarrhoea in weaned pigs. The age at weaning did not change after the withdrawal of AGPs.

The influence of diet on Lawsonia intracellularis colonization in pigs upon experimental challenge

The objective of this investigation was to study if different feeding strategies influence experimental infections of pigs with Lawsonia intracellularis, the causative agent of proliferative enteropathy. In three sequential trials, a total of 144 weaned pigs were fed five different diets all made from a standard diet based on wheat and barley as carbohydrate source and soybean as protein source. The five diets were: a standard diet (fine ground and pelleted), the standard diet fed as fermented liquid feed, the standard diet added 1.8% formic acid, the standard diet added 2.4% lactic acid and a diet similar to the standard diet (made from the same ingredients), but fed coarse ground. Twenty-four pigs on each diet were orally inoculated with L. intracellularis and growth performance and faecal excretion of bacteria were monitored. Twenty-four pigs fed the standard diet were included as not experimentally infected controls. Pigs in the first two trials were sacrificed 4 weeks post-inoculation, whereas animals in the third trial were sacrificed after 5 weeks. Pigs in all experimentally infected groups excreted L. intracellularis. The fermented liquid diet delayed the excretion of L. intracellularis and furthermore, pigs fed the standard diet supplemented with lactic acid had limited pathological lesions when the intestines were examined 4 weeks after inoculation. The growth performance was reduced in pigs experimentally challenged with L. intracellularis, however the prevalence and severity of diarrhea was limited.

Effect of gilt seropositivity to Lawsonia intracellularis (LI) on their offspring’s seropositivity to LI and on diarrhoea after a pure-culture challenge

This study was done in a large Croatian pig-production unit. Blood samples from late-pregnancy gilts were tested by an indirect immunofluorescence-antibody (IFA) serum assay for Lawsonia intracellularis (LI). Ten IFA-positive and 10 IFA-negative gilts were selected. The 2-week-old piglets (97 from positive gilts, and 98 from negative gilts) were inoculated intragastrically with pure culture of LI. All pigs were tested until slaughter for seroprevalence of LI. Blood samples were collected at 5, 8, 11, 14, 17, 20, 23 and 26 weeks of age. Seropositivity in offspring of IFA-negative gilts was highest at age 5 weeks (84%) and declined gradually from week 11 to only 10% at week 26. At the same time, the offspring of IFA-positive gilts showed lower and faster-decaying seroprevalence: only 32% at week 5 and 0% starting at week 17. There was no difference in the pen-days of diarrhoea between the offspring of LI-seropositive and -seronegative gilts.

Patterns of exposure to Lawsonia intracellularis infection on European pig farms

A serological investigation was made of the patterns of exposure of pigs to Lawsonia intracellularis, the causative agent of proliferative enteropathy (ileitis), on farms in France and Spain. Blood samples from groups of adult female pigs in breeding programmes and from postweaning pigs were monitored, the latter every month for five months, by a L. intracellularis-specific immunofluorescence seroassay. Four of 33 farms monitored in France (12 per cent) and three of 29 farms monitored in Spain (10.3 per cent) remained free of clinical signs and seronegative throughout the study. The postweaning pigs on all of the remaining French farms and on 20 of the 26 remaining Spanish farms had a pattern of infection characterised by seroconversion in the grower period, generally between eight and 16 weeks of age. The seroprevalence in these groups ranged from 8 to 20 per cent. On all of these farms at least 15 per cent of the breeding females tested were seropositive, and the farms were under similar management systems, with a continuous flow of pigs or between buildings on one site, so-called 'one site, farrow-to-finish'. On the six remaining Spanish farms, under two management groups, a multiple-site system was used, with the piglets being separated from the adults at weaning and moved to a separate location. On three of these farms, the pattern of infection was characterised by seroconversion later in the finisher period, at between 16 and 20 weeks of age, and none of the breeding females was seropositive. On the three other multiple-site farms the pattern of infection resembled that on the one-site farms. On all of the farms, the seroconversion of groups of pigs was frequently associated with clinical or subclinical signs of ileitis.

Risk factors for intestinal pathogens in Danish finishing pig herds

The objective of this investigation was to identify risk factors for infection with the intestinal bacteria: Lawsonia intracellularis, Brachyspira hyodysenteriae, Serpulina intermedia, Brachyspira innocens, Brachyspira pilosicoli and swine-pathogenic Escherichia coli (serogroups O138, O139, O141 and O149) in Danish finishing pig herds.A total of 79 herds was randomly selected and visited during 1998. From each herd, 20 faecal samples were collected from individual pigs weighing 30-50 kg. In total, 1580 faecal samples were collected and examined by polymerase chain reaction (L. intracellularis) or culture (all other agents). Information on feed and management procedures was collected by filling in questionnaires at the herd visits. The questionnaires included information on 29 dichotomous variables and three continuous variables. Variables with P<0.25 in a preliminary screening (chi2- or t-test) were selected for the statistical modelling. Our conclusions, based on the results of multifactorial logistic regression (cut-off: P=0.05), were the following: 1. Consistent batch production was associated with reduced prevalences of L. intracellularis and weakly -haemolytic spirochetes (S. intermedia, B. innocens, B. pilosicoli) (OR's=0.43 and 0.06, respectively). 2. Home-mixed (and/or non-pelleted) feed was associated with reduced prevalences of L. intracellularis and weakly -haemolytic spirochetes (OR's=0.6 and 0.4, respectively). 3. Providing straw to finishers was associated with a reduced prevalence of weakly -haemolytic spirochetes (OR=0.28-0.32). 4. Not using antimicrobial growth promoters for piglets was associated with an increased prevalence of S. intermedia (OR=11.11). 5. Rare occurrence of post-weaning diarrhoea (as opposed to common) was associated with an increased prevalence of weakly -haemolytic spirochetes (OR=8.3-13.7).

Risk factors associated with clinical mastitis in low somatic cell count British dairy herds

A cross-sectional survey of dairy farms with low bulk milk somatic cell counts was carried out to assess the level of clinical mastitis and to quantify risk factors associated with the incidence rate of clinical mastitis. Questionnaires were sent to 3009 milk operations with an annual mean bulk milk somatic cell count of less than 100,000 cells/ml during 1997. A response rate was 61%. The mean incidence of clinical mastitis reported was 22.8 cases per 100 cows/yr. Negative binomial regression models were used to assess statistically significant risk factors associated with the incidence of clinical mastitis. The incidence increased when farmers reported that they had straw yard housing for milking cows (compared with cubicle housing), mucked out the calving area less frequently than once per month, kept cows standing in a yard after milking, always practiced postmilking teat disinfection, had greater than 50% replacement rate, had some cows that leaked milk on entry to the parlor, had some cows that leaked milk at other times, and foremilked before cluster attachment. The incidence of clinical mastitis was lower on farms when the gathering yard used before milking was scraped at least twice a day, cows were offered feed after both milkings, rubber gloves were not worn during milking, teat liners were changed after 6000 milkings, and the average dry period was less than 40 d. The study has identified areas of the environment in which efforts to improve hygiene should be focused.

Prevalence of intestinal pathogens in Danish finishing pig herds

Our aim was to determine the prevalence of the intestinal bacteria: Lawsonia intracellularis, Brachyspira hyodysenteriae, Serpulina intermedia, Brachyspira innocens, Brachyspira pilosicoli, pathogenic Escherichia coli (serogroups O138, O139, O141 and O149) and Salmonella enterica in Danish finishing pig herds. A total of 79 herds was randomly selected and visited during 1998. From each herd, 20 faecal samples were collected from individual pigs weighing 30-50kg. Furthermore, 10 pooled pen samples were collected and examined for S. enterica. In total, 1580 faecal samples and 790 pen samples were collected and examined by polymerase chain reaction (PCR) or culture. L. intracellularis was found in 74 herds (93.7%), B. hyodysenteriae in two herds (2.5%), S. intermedia in 10 herds (12. 7%), B. innocens in 27 herds (34.2%), B. pilosicoli in 15 herds (19. 0%), pathogenic E. coli in 19 herds (24.1%) and S. enterica in eight herds (10.1%). The within-herd prevalences of L. intracellularis and B. hyodysenteriae were 25-30%; the within-herd prevalences of the other agents were 5-10%. Three herds (4%) were not infected with any of the bacteria and 25 herds (32%) were only infected with L. intracellularis.

Therapeutic efficacy of water-soluble lincomycin-spectinomycin powder against porcine proliferation enteropathy in a European field study

Controlled clinical trials to a standardised protocol were conducted into the effect of a water-soluble antibiotic on proliferative enteropathy and its causative agent (Lawsonia intracellularis) on commercial pig farms at six sites in four European countries. Clinical signs of the disease and L intracellularis-specific polymerase chain reaction (PCR)-positive pigs were detected in pens of six- to 12-week-old pigs (weighing 5 to 55 kg) immediately before each trial. Matched pens of randomised pigs were either left unmedicated (32 to 59 pigs per trial), or medicated orally with 10 mg/kg of a water-soluble combination of lincomycin and spectinomycin powder (21 and 42 mg, respectively, of antibiotic activity per litre) for either seven days (33 to 61 pigs per trial), or 14 days (33 to 61 pigs per trial), delivered via the drinking water. Investigators did not know which pens received which treatment In most of the affected pigs in each trial, diarrhoea due to L intracellularis resolved within three to seven days after the medication began, whereas most unmedicated pigs remained diarrhoeic for at least 10 days. On average the medicated pigs gained more weight than the unmedicated pigs over the 21-day trial period (P=0.01). In two trials, the absence of L intracellularis after the treatment ended was confirmed by the PCR.

Monitored control programme for proliferative enteropathy on British pig farms

The effect of control programmes on proliferative enteropathy and its causative agent (Lawsonia intracellularis) was investigated on four farrow-to-finish pig farms in Britain. Faeces samples from groups of boars and gilts in breeding programmes, and from preweaning and postweaning pigs were monitored prospectively every month for six months by a L intracellularis-specific polymerase chain reaction (PCR). On one farm with 150 sows, an outbreak of acute proliferative enteropathy in boars and gilts was controlled clinically by the use of tiamulin and chlortetracycline. The percentage of detectable PCR-positive pigs decreased from between 50 to 70 per cent to zero in the treated pigs and their progeny less than 14 weeks old, but clinical signs of the disease and PCR-positive pigs were detected in some 14-week-old pigs derived from the treated groups. On another farm with 160 sows, an outbreak of chronic proliferative enteropathy in six-week-old pigs (23 to 26 per cent PCR-positive) was controlled by the use of oral tylosin phosphate. Faeces samples from the medicated pigs on this farm remained PCR-negative during the study period, whereas samples from unmedicated control pigs showed that the infection persisted in some pigs for at least six weeks. The two other monitored farms remained PCR-negative and clinically negative for the disease during the study period. These farms treated the pigs regularly with oral chlortetracycline.