Epidemiological features of porcine proliferative enteropathy

A polymerase chain reaction (PCR) assay was adapted and optimised for specific detection of Lawsonia intracellularis genomic DNA segment in swine faeces. Lawsonia intracellularis is the aetiological agent of porcine proliferative enteropathy (PPE) and the PCR represents the first diagnostic test suitable for ante-mortem use in affected swine. Various methods designed to extract bacterial DNA from faeces were evaluated to establish a convenient and optimum protocol. The PCR was utilised in pig challenge studies to investigate the excretion patterns of L. intracellularis in weaner pigs orally inoculated with pure cultures of L. intracellularis. This challenge work demonstrated that the PCR was a suitable tool for detection of infection, and indicated that individual animals could excrete L. intracellularis organisms for periods of up to ten weeks post-challenge. Such an excretion period has major implications for the transmission of organisms in the field. For example, if infected growers are still shedding L. intracellularis organisms upon entry to the breeding population, then this is a possible route for the transmission of disease to younger, susceptible pigs.younger, susceptible pigs. A more extensive, two-part investigation of the epidemiological aspects of PPE in the field followed. The investigation comprised a farm sampling study and a questionnaire postal survey. In the farm sampling study, faeces samples were collected serially over a ten month period from breeding gilts and their litters. Samples were subjected to PCR for the detection of infection, allowing estimation of within-herd prevalence, as well as determination of possible transmission patterns. The assay successfully detected the presence of L. intracellularis in the weaners and/or growers of three of the five farms selected for this study. The within-herd prevalence for these age-groups ranged from 10 to 30%. The PCR also confirmed infection in several of the adult breeding boars and gilts. The relative expense of the PCR assay dictates that its practical application, at least for the purposes of research, must be targeted. Thus, the sampling study was coupled with a postal questionnaire survey. Mailing questionnaires to almost 600 commercial production units achieved a 56% response rate. This provided a sufficiently large number of herds to allow statistical analysis of possible risk factors involved in the epidemiology of PPE. This survey indicated that the 1993 to 1995 period-prevalence of PPE in the UK was 31%. Based on the number of sows, herd size was an important risk factor, even when herds with under 50 sows were excluded (p<0.005). There was an important link between the occurrence of PE and nucleus herds, with five out of six nucleus herds in the study having had PE diagnosed in the previous three years. This link was strengthened in that herds obtaining replacement breeding boars from nucleus stock were at an increased risk of PE (p<0.05). Factors which could affect the exposure of animals to the faecally-contaminated environment were also significant. Surprisingly, slatted or meshed floors were linked to PE, especially in the younger age-groups (p<0.05). Batch movement of pigs on a house basis was significantly protective against PE (p<0.05), but batch movement on a pen basis only was neither a protective nor a risk factor.Epidemiology of PPE is complex, but the PCR has proved to be a valuable tool, capable of screening for the presence of L. intracellulars in field conditions. Additionally, its use has permitted some initial conclusions to be drawn regarding the excretion and transmission patterns of this unique organism

Review of methods for the detection of Lawsonia intracellularis infection in pigs

Lawsonia intracellularis is an obligate intracellular bacterium associated with enteric disease in pigs. Clinical signs include weight loss, diarrhea, and, in some cases, sudden death. The hallmark lesion is the thickening of the intestinal mucosa caused by increased epithelial cell replication, known as proliferative enteropathy. The immune response to L. intracellularis is not well defined, and detection of the infection, especially in the early stages, is still a significant challenge. We review here the main approaches used to identify this important but poorly understood pathogen. Detection of L. intracellularis infection as the cause of clinical disease is confounded by the high prevalence of the pathogen in many countries and that several other pathogens can produce similar clinical signs. A single L. intracellularis–specific ELISA and several amplification assays are available commercially to aid detection and surveillance, although histopathology remains the primary way to reach a conclusive diagnosis. There are major gaps in our understanding of L. intracellularis pathogenesis, especially how the host responds to infection and the factors that drive infection toward different clinical outcomes. Knowledge of pathogenesis will increase the predictive value of antemortem tests to guide appropriate interventions, including identification and treatment of subclinically affected pigs in the early stages of disease, given that this important manifestation reduces pig productivity and contributes to the economic burden of L. intracellularis worldwide

A COMPARISON OF COMPUTED TOMOGRAPHIC, RADIOGRAPHIC, GROSS AND HISTOLOGICAL, DENTAL AND ALVEOLAR FINDINGS IN 30 ABNORMAL CHEEK TEETH FROM EQUINE CADAVERS

BackgroundEquine cheek teeth disorders, especially pulpar/apical infections, can have very serious consequences due to the frequent extension of infection to the supporting bones and/or adjacent paranasal sinuses. Limited studies have assessed the accuracy of computed tomographic (CT) imaging in the diagnosis of these disorders, and no study has directly compared imaging and pathological findings of the alveoli of diseased equine cheek teeth.ObjectiveTo validate the accuracy of CT and radiographic imaging of cheek teeth disorders by comparing CT and radiographic imaging, gross and histological findings in abnormal cheek teeth and their alveoli extracted from equine cadaver heads.Study designEx vivo original study.MethodsFifty-four cadaver heads from horses with unknown histories that had died or been euthanized on humane grounds obtained from a rendering plant had radiography, CT imaging, and gross pathological examinations performed. Based on imaging and gross examination findings, 30 abnormal cheek teeth (26 maxillary and 4 mandibular) identified in 26 heads were extracted along with their dental alveoli where possible, and further CT imaging, gross, and histological examinations were performed. Eight maxillary cheek teeth (including four with attached alveolar bone) from these heads, that were normal on gross and CT examinations, were used as controls.ResultsGross pathological and histological examinations indicated that 28/30 teeth, including two supernumerary teeth, had pulpar/apical infection, including pulpar and apical changes. A further supernumerary and a dysplastic tooth were also identified. Abnormal calcified tissue architecture was present in all three supernumerary and in the dysplastic tooth. CT imaging strongly indicated the presence of pulpar/apical infection in 27 of the 28 (96.4%) pulpar/apically infected teeth, including the presence of intrapulpar gas (N = 19/28), apical clubbing (N = 20), periapical halo (N = 4), root lysis or fragmentation (N = 7), and periapical gas (N = 2). Also present were alveolar bone sclerosis (N = 20), alveolar bone thickening (N = 3), and lytic/erosive changes (N = 8). Radiographic abnormalities strongly indicative of pulpar/apical infection including periapical sclerosis (N = 8/28) and apical clubbing (N = 14/28) were found in 14/28 (50%) of apically infected teeth. Histological changes were present in alveolar bone of all 21 cases of apical infection where alveolus remained attached to the tooth and was marked in 16 cases, all which had CT alveolar changes. Histological changes included disruption of the normal trabecular pattern, increased osteoclastic activity, and the presence of islands of bone with a scalloped profile within the thickened attached periodontal ligament. No gross pathological or histological changes were present in the eight control teeth or their alveoli (N = 4).Main limitationsNo history or breed-related information was available on these cases.ConclusionThere was a 96.4% correlation between a CT diagnosis and confirmative pathological findings in 28 apically infected teeth confirming the accuracy of CT imaging in diagnosing equine pulpar/apical infections. There was also excellent correlation between CT and histological alveolar bone findings

Histological and molecular characterisation of feline humeral condylar osteoarthritis

&lt;p&gt;Background: Osteoarthritis (OA) is a clinically important and common disease of older cats. The pathological changes and molecular mechanisms which underpin the disease have yet to be described. In this study we evaluated selected histological and transcriptomic measures in the articular cartilage and subchondral bone (SCB) of the humeral condyle of cats with or without OA.&lt;/p&gt; &lt;p&gt;Results: The histomorphometric changes in humeral condyle were concentrated in the medial aspect of the condyle. Cats with OA had a reduction in articular chondrocyte density, an increase in the histopathological score of the articular cartilage and a decrease in the SCB porosity of the medial part of the humeral condyle. An increase in LUM gene expression was observed in OA cartilage from the medial part of the humeral condyle.&lt;/p&gt; &lt;p&gt;Conclusions: Histopathological changes identified in OA of the feline humeral condyle appear to primarily affect the medial aspect of the joint. Histological changes suggest that SCB is involved in the OA process in cats. Differentiating which changes represent OA rather than the aging process, or the effects of obesity and or bodyweight requires further investigation.&lt;/p&gt

Lung injury caused by aspiration of organophosphorus insecticide and gastric contents in pigs

INTRODUCTION: Patients who require mechanical ventilation after self-poisoning with ingested organophosphorus (OP) insecticides often die. Aspiration of stomach contents may contribute to lung injury and lethality. This study was designed to assess the severity of direct and indirect pulmonary injury created by pulmonary instillation of mixtures of OP insecticide, solvent (Solv) and porcine gastric juice (GJ) compared to controls. METHODS: Terminally anaesthetised minipigs (groups n = 5) were exposed to sham bronchoscopy or given mixtures (0.5 mL/kg) of: saline, GJ, OP insecticide and GJ (OP + GJ), or Solv and GJ (Solv + GJ), placed into the right lung, and monitored for 48 h. Lung injury was assessed through analysis of bronchoalveolar lavage fluid (BALF), computed tomography and histopathology. RESULTS: OP + GJ created a direct lung injury consisting of neutrophil infiltration, oedema and haemorrhage, as well as indirect injury to the other lung. OP + GJ directly-injured lung parenchyma had increased concentrations of BALF protein, albumin, IL-6, IL-8 and C-reactive protein (CRP) at 24 h (p < 0.05), and BALF protein, albumin and CRP at 48 h (p < 0.05), when compared with controls. Aspiration of GJ produced similar direct effects to OP + GJ but less indirect lung injury. Lung injury was less severe after Solv + GJ, for combined lung histopathology scores (vs. OP + GJ, p < 0.05) and for the proportion of directly-injured lung that was poorly/non-aerated at 48 h. CONCLUSION: Pulmonary instillation of OP + GJ created more lung damage than controls or Solv + GJ. In patients with severe OP insecticide poisoning and reduced consciousness, early airway protection is likely to reduce pulmonary damage