Marie Sjölund

Isolation of spirochetes of genus Treponema from pigs with ear necrosis

Various ear lesions, often caused by ear biting, are common in pigs. Some herds have a high frequency of ear necrosis, a syndrome characterized by necrotic lesions along the rim of the pinna, often bilateral and sometimes resulting in loss of the entire ear. In samples from such lesions spirochetes have been observed microscopically but never isolated or identified. In this study two herds with periodic outbreaks of ear necrosis among weaners were investigated. Samples were collected from ear lesions and from the gingiva of the pigs. Spirochetes were observed in silver stained histological sections and by phase contrast microscope in scrapings from the necrotic lesions. From an ear lesion a pure spirochete isolate was obtained and identified as a yet unnamed species of genus Treponema, closely related to spirochetes found in digital dermatitis in cattle. From the oral samples two pure isolates were obtained. One of these isolates was identified as the same species as in the ear lesion and one as Treponema socranskii. Species identification was based on 16S rRNA gene sequences.

Alternatives to the use of antimicrobial agents in pig production: A multi-country expert-ranking of perceived effectiveness, feasibility and return on investment

Nineteen alternatives to antimicrobial agents were ranked on perceived effectiveness, feasibility and return on investment (ROI) from 0 (not effective, not feasible, no ROI) to 10 (fully effective, completely feasible, maximum ROI) by 111 pig health experts from Belgium, Denmark, France, Germany, Sweden and Switzerland. The top 5 measures in terms of perceived effectiveness were (1) improved internal biosecurity, (2) improved external biosecurity, (3) improved climate/environmental conditions, (4) high health/Specific Pathogen Free/disease eradication and (5) increased vaccination. The top 5 measures in terms of perceived feasibility were (1) increased vaccination, (2) increased use of anti-inflammatory products, (3) improved water quality, (4) feed quality/optimization and (5) use of zinc/metals. The top 5 measures in terms of perceived ROI were (1) improved internal biosecurity, (2) zinc/metals, (3) diagnostics/action plan, (4) feed quality/optimization and (5) climate/environmental improvements. Univariate linear regression showed that veterinary practitioners rank internal biosecurity, vaccination, use of zinc/metals, feed quality optimization and climate/environmental on average highest, while researchers and professors focused more on increased use of diagnostics and action plans. Financial incentives/penalties ranked low in all countries. Belgian respondents ranked feed quality significantly lower compared to the German respondents while reduction of stocking density was ranked higher in Belgium compared to Denmark. Categorical Principal Component Analysis applied to the average ranking supported the finding that veterinary practitioners had a preference for more practical, common and already known alternatives. The results showed that improvements in biosecurity, increased use of vaccination, use of zinc/metals, feed quality improvement and regular diagnostic testing combined with a clear action plan were perceived to be the most promising alternatives to antimicrobials in industrial pig production based on combined effectiveness, feasibility and ROI.

The biosecurity status and its associations with production and management characteristics in farrow-to-finish pig herds

Disease prevention through biosecurity measures is believed to be an important factor for improvement of the overall health status in animal production. This study aimed at assessing the levels of implementation of biosecurity measures in pig production in four European Union (EU) countries and to describe possible associations between the biosecurity level and farm and production characteristics. A cross-sectional study was conducted in 232 farrow-to-finish pig herds in Belgium, France, Germany and Sweden between December 2012 and December 2013. The biosecurity status in each of these herds was described and quantified by using the risk-based scoring tool Biocheck.UGentTM (www.biocheck.ugent.be). Production and management characteristics, obtained from the herd management system and by interviewing the farmer, were analysed for their association with the biosecurity level. A causal path was designed to study statistical associations. The results showed that there was substantial room for improvement in the biosecurity status on many pig farms. Significant differences (P<0.01) both in internal and external biosecurity levels were observed between countries. The external biosecurity status, combining all measures taken to prevent disease introduction into the herd, was highest in Germany and lowest in France. The internal biosecurity status, combining all measures taken to prevent within herd disease transmission, was highest in Sweden and lowest, with a large variation, in Belgium. External biosecurity scores were in general higher compared to internal biosecurity scores. The number of pathogens vaccinated against was significantly associated with internal biosecurity status, suggesting an overall more preventive approach towards the risk of disease transmission. A higher external biosecurity was associated with more weaned piglets per sow per year. Furthermore also the weaning age and the mortality till weaning were highly associated with the number of weaned piglets per sow per year. The negative association observed between the biosecurity level and the estimated frequency of treatment against certain clinical signs of disease as a proxy for disease incidence is consistent with the hypothesis that a higher biosecurity level results in healthier animals. These findings promote an improved biosecurity status at pig farms and are of relevance in the discussion on alternative ways to keep animals healthy with a reduced necessity of antimicrobials; Prevention is better than cure!

Quantitative and qualitative antimicrobial usage patterns in farrow-to-finish pig herds in Belgium, France, Germany and Sweden

Data on sales of antimicrobials using a standardised methodology have shown that there are vast differences between countries in amounts of antimicrobials sold for food-producing animals, but these data do not provide insight on how sales are distributed by species and age groups. The aim of this study was to compare herd level antimicrobial usage for pigs by age category, antimicrobial class and administration route for farrow-to-finish herds in four EU countries. A cross-sectional study was conducted among 227 farrow-to-finish pig herds with at least 100 sows and 500 finishing pigs in Belgium (n=47), France (n=60), Germany (n=60) and Sweden (n=60). Detailed information about the antimicrobial consumption for breeding and growing pigs was collected. Antimicrobial usage was quantified as active substance expressed as mg and then converted to treatment incidence (TI) based on Defined Daily Doses Animal per 1000 pig-days at risk. TIs varied between and within countries, herds and age groups. The Swedish herds had the lowest and the German herds the highest overall use. Most treatments were applied to weaned piglets except in the Swedish herds where treatments of suckling piglets were most frequent. Antimicrobials were most often applied through feed or water except in the Swedish herds where parenteral treatments were most frequent. Aminopenicillins was the antimicrobial class most commonly used. Use of third and fourth generation cephalosporins constituted 11% of use for the Belgian herds, which was higher compared to the other countries. There was a significant (p<0.01) association between the within-herd antimicrobial use across different age categories. This study has shown that there were large differences in antimicrobial use for pigs between countries, herds and age groups in farrow-to-finish herds of similar size when actual consumption data were compared. Collecting detailed usage data can be used to efficiently target high users in order to reduce antimicrobial consumption.

Biosecurity level and health management practices in 60 Swedish farrow-to-finish herds

BackgroundBiosecurity measures are important tools to maintain animal health in pig herds. Within the MINAPIG project, whose overall aim is to evaluate strategies to raise pigs with less antimicrobial use, biosecurity was evaluated in medium to large farrow-to-finish pig herds in Sweden. In 60 farrow-to-finish herds with more than 100 sows, the biosecurity level was evaluated using a previously developed protocol (BioCheck). In a detailed questionnaire, internal and external biosecurity was scored in six subcategories each. An overall score for biosecurity was also provided. Information regarding production parameters as well as gender and educational level of personnel working with the pigs was also collected. Descriptive statistics were used to examine the recorded data.ResultsThe median scores for external and internal biosecurity were 68 and 59, respectively, where 0 indicates total absence of biosecurity and 100 means maximal possible biosecurity. The subcategories for external and internal biosecurity that had the highest scores were “Purchase of animals” (external) and “Nursery unit”/“Fattening unit” (internal), while “Feed, water and equipment supplies” (external) and “Measures between compartments and equipment”/“Cleaning and disinfection” (internal) received the lowest scores. A female caretaker in the farrowing unit, a farmer with fewer years of experience and more educated personnel were positively associated with higher scores for some of the external and internal subcategories. In herds with <190 sows, fattening pigs were mixed between batches significantly more often than in larger herds.ConclusionsThe herds in this study had a high level of external biosecurity, as well as good internal biosecurity. Strong biosecurity related to the purchase of animals, protocols for visitors, the use of all-in, all-out systems, and sanitary period between batches. Still, there is room for improvement in preventing both the introduction of disease to herds (external) and the spread of infections within herds (internal). Systems for animal transport can be improved and with respect to internal biosecurity, there is especially room for improvement regarding hygiene measures in and between compartments, as well as the staff’s working procedures between different groups of pigs.

Evaluation of the relationship between the biosecurity status, production parameters, herd characteristics and antimicrobial usage in farrow-to-finish pig production in four EU countries

BackgroundHigh antimicrobial usage and the threat of antimicrobial resistance highlighted the need for reduced antimicrobial usage in pig production. Prevention of disease however, is necessary to obtain a reduced need for antimicrobial treatment. This study aimed at assessing possible associations between the biosecurity level, antimicrobial usage and farm and production characteristics in order to advice on best practices for a low antimicrobial usage and maximum animal health and production.A cross-sectional study was conducted in 227 farrow-to-finish pig herds in Belgium, France, Germany and Sweden between December 2012 and December 2013. Associations between biosecurity status, antimicrobial usage, and production parameters were evaluated with multivariable general linear models, according to an assumed causal pathway.ResultsThe results showed that higher antimicrobial usage in sows tended to be associated with higher antimicrobial usage from birth until slaughter (p = 0.06). The antimicrobial usage from birth until slaughter was positively associated with the number of pathogens vaccinated against (p < 0.01). A shorter farrowing rhythm (p < 0.01) and a younger weaning age (p = 0.06) tended to be also associated with a higher antimicrobial usage from birth until slaughter whereas a better external biosecurity (p < 0.01) was related with a lower antimicrobial usage from birth until slaughter.ConclusionManagement practices such as weaning age and biosecurity measures may be important factors indirectly impacting on antimicrobial usage. We therefore promote a holistic approach when assessing the potential to reduce the need for antimicrobial treatments.

Antimicrobial usage in 60 Swedish farrow-to-finish pig herds.

The aim of this study was to quantify antimicrobial consumption in Swedish farrow-to-finish pig herds. Sixty herds with 100 sows or more producing more than 500 fatteners per year participated in a study where data on antimicrobial consumption over a period of one year were collected. Data on antimicrobial use were collected by substance, administration route and per age category. Antimicrobial use was measured as defined daily doses and expressed as treatment incidence (TI) per 1000 pig-days at risk. The TIs for growing pigs varied between herds, from 1.6 to 116.0 with a median of 14.3. The highest TI was recorded for suckling piglets with a median of 54.7 (range; 1.6-367.9), while the median TIs for weaners, fatteners and adults were 6.2, 2.8 and 8.4, respectively (range; 0.0-260.5; 0.0-64.9; 0.0-45.0, respectively). The within herd TIs for the different age categories were not correlated. Individual treatment, mainly consisting of injectables, was the most common form of application except for weaners for which a majority (54.8%) of the treatments were group treatments. Benzylpenicillin was the most commonly applied substance except for weaners for which oral formulations of tylosin were most common. For fatteners, group treatments constituted 8.4% of the total TI. Group treatments with oral colistin were applied to suckling piglets in five herds. Group treatments were not applied to adult pigs. The TI for weaners was significantly lower for specific pathogen-free herds. The results show that the overall antimicrobial use in Swedish farrow-to-finish pig herds varied to a great extent, and the between-herd variation indicates that there is room for improvement of pig health. Targeting suckling piglets may be most beneficial, but further studies are required to identify specific focus areas which may reduce the need for antimicrobials in this particular age group.

Field experience with two different vaccination strategies aiming to control infections with Actinobacillus pleuropneumoniae in a fattening pig herd

BackgroundThe prevalence of pleurisies recorded at slaughter is increasing in Sweden, and acute outbreaks of actinobacillosis that require antimicrobial treatments have become more frequent. As an increased use of antimicrobials may result in the development of antimicrobial resistance it is essential to develop alternative measures to control the disease. Vaccinations present an appealing alternative to antimicrobial treatments. The aim of this work was to evaluate the potential of two different vaccination strategies in a specialized fattening herd affected by actinobacillosis.MethodsThe study was conducted in a specialized fattening herd employing age segregated rearing in eight units. The herd suffered from infections caused by Actinobacillus pleuropneumoniae serotype 2, confirmed by necropsy and serology. The study included 54 batches of pigs grouped into five periods. Batches of pigs of the second period were vaccinated against actinobacillosis twice, and pigs in the fourth period were vaccinated three times. Batches of pigs of the first, third and fifth period were not vaccinated. Concentrations of serum antibodies to A. pleuropneumoniae and serum amyloid A (SAA) were analysed and production data were recorded.ResultsDespite vaccinating, medical treatments were required to reduce the impact of the disease. The mean incidence of individual treatments for respiratory diseases during the rearing period ranged from 0 to 4.7 ± 1.8%, and was greatest during the triple vaccination period (period IV; p < 0.05 when compared to other groups). A large proportion of the vaccinated pigs seroconverted to A. pleuropneumoniae serotype 2 in the absence of a SAA-response. The prevalence of pleuritis decreased from 25.4 ± 6.5% in the first period to 5.0 ± 3.7% in the fifth period (p < 0.001).ConclusionsThe vaccine did not effectively prevent clinical expression of A. pleuropneumoniae infections, but seroconversion to A. pleuropneumoniae in the absence of a SAA-response in a large number pigs indicated that the vaccine had activated the immune system. Further, the prevalence of pleuritis decreased with time. This indicates that vaccinations together with intensified medical treatments of affected pigs could be useful in reducing the impact of A. pleuropneumoniae serotype 2 infections.

Responses of pigs to a re-challenge with Actinobacillus pleuropneumoniae after being treated with different antimicrobials following their initial exposure

Four groups of six specific pathogen-free (SPF) pigs were inoculated intranasally with Actinobacillus pleuropneumoniae serotype 2 and treated with either enrofloxacin, tetracycline or penicillin at the onset of clinical disease, or left untreated. A fifth group was left uninoculated. The inoculated control and the penicillin-treated groups developed severe disease, but the groups treated with enrofloxacin and tetracycline recovered rapidly. All the inoculated pigs, except those treated with enrofloxacin developed serum antibodies to A pleuropneumoniae. On day 28, all five groups were challenged with A pleuropneumoniae without any subsequent treatment. The previously uninoculated control group and the enrofloxacin-treated group developed severe disease, but the three seropositive groups remained unaffected.

Effects of different antimicrobial treatments on serum acute phase responses and leucocyte counts in pigs after a primary and a secondary challenge infection with Actinobacillus pleuropneumoniae

The susceptibility to an initial challenge and a re-challenge inoculation with Actinobacillus pleuropneumoniae was analysed in pigs that were treated with antimicrobials of different efficacies following the first exposure to A pleuropneumoniae. In brief, 30 nine-week-old specific pathogen-free pigs were allocated to five groups of six. After acclimatisation, four groups were inoculated with A pleuropneumoniae serotype 2. At the onset of clinical signs, three of the groups of pigs were treated with enrofloxacin, tetracycline or penicillin. A fourth group served as the inoculated control and the fifth group as a control group that had not been inoculated. On day 28, all five groups were re-challenged with the same strain of A pleuropneumoniae serotype 2 as had been used in the first inoculation. No treatments were carried out at this time. The acute phase responses and differential leucocyte counts were monitored in detail after both inoculations. Leucocytosis and acute phase responses in the forms of serum amyloid A, pig-major acute phase protein and haptoglobin were recorded in all of the inoculated groups after the onset of clinical signs following the first inoculation. A porcine mannan-binding lectin-A response was less evident in the pigs. Acute phase responses resembling those of the first inoculation were observed in the pigs that had not previously been inoculated and in the pigs treated with enrofloxacin. Acute phase responses were not recorded in the other three groups, where the pigs had seroconverted to A pleuropneumoniae serotype 2 following the first inoculation.