Penetration of amoxycillin into the respiratory tract tissues and secretions in pigs

The pharmacokinetic properties of amoxycillin, and its penetration into respiratory tract tissues (alveolar macrophages, bronchial secretions, bronchial mucosa, lung tissue and lymph nodes), were determined in 20 healthy female pigs weighing 29 to 55 kg, after a single intravenous dose of 8·6 mg kg ⁻¹ bodyweight. Following intravenous administration the plasma concentration-time curves were best described by a three-compartment open model. The elimination half-life and the mean residence time were 2·5 and 1.4 hours, respectively. The volume of distribution at steady state was 0·52 litres kg ⁻¹, and the body clearance was 0·40 litres hour⁻¹ kg⁻¹. In all structures (except alveolar macrophages) amoxycillin concentration peaked at the first sampling point, one hour after drug administration. The tissue to plasma ratio (based on AUC values) were 0·33 for bronchial secretions, 0·37 for bronchial mucosa, 0·39 for lung tissue and 0·68 for lymph nodes. Traces of amoxycillin were found in alveolar macrophages, but the concentrations were below the limit of quantification. The concentration of amoxycillin in secretions and tissue decreased by a slower rate than the concentration in plasma, resulting in increasing secretion- and tissue-to-plasma concentration ratios.     

Spatial and temporal patterns of pig herds diagnosed with Postweaning Multisystemic Wasting Syndrome (PMWS) during the first two years of its occurrence in Denmark

The clinical syndrome Postweaning Multisystemic Wasting Syndrome (PMWS) in pigs has emerged globally during the last decade. In October 2001, the first pig herd diagnosed with PMWS was reported in Denmark, and since then the number of herds diagnosed with PMWS has increased markedly. The etiology of PMWS is not well understood, but increased knowledge of the causal factors is prerequisite for applying preventive interventions. In this study we described the temporal (time of diagnosis), spatial (location of herds) and spatio-temporal pattern of Danish pig herds diagnosed with PMWS during the first two years after the first herd was diagnosed, and we tested for spatial and spatio-temporal clustering using scan statistics. The study population consisted of pig herds that during the study period (October 2001-September 2003) performed diagnostic submissions to the two major veterinary diagnostic laboratories in Denmark (6724 herds). Of these, 277 herds were diagnosed with PMWS. Two statistically significant spatial clusters of herds diagnosed with PMWS were identified. These clusters included 11% and 8% of the study herds, respectively. Within these two clusters the relative risk for a herd to be diagnosed with PMWS was twice as high as expected. One statistically significant spatio-temporal cluster was identified between February and May 2002. We discuss different hypotheses that could explain why pig herds diagnosed with PMWS were clustered both spatially and spatio-temporally, and conclude that the results support the hypothesis that PMWS is caused by introduction of a new, unidentified, pathogen into the Danish pig production.     

Pharmacokinetics and penetration of danofloxacin into the gastrointestinal tract in healthy and in Salmonella typhimurium infected pigs

The pharmacokinetics and penetration of danofloxacin into the gastrointestinal tract in healthy pigs and in pigs experimentally infected with Salmonella typhimurium were studied.In the infected pigs, a decrease in body clearance and an increase in mean elimination half-life was observed (P < 0.01). Moreover a significant reduction in the volume of the peripheral compartment was found. Danofloxacin distributed well to the gastrointestinal tract achieving high AUC / AUC(plasma)ratios in both groups of pigs. However, compared to the healthy pigs AUC / AUC(plasma)ratios decreased in the infected pigs. Salmonella infection led to an increase in mean residence time (MRT) in the small intestines and lymph nodes and a decrease in MRT in caecum and colon.     

Mycoplasma hyosynoviae in joints with arthritis in abattoir baconers.

The occurrence of Mycoplasma hyosynoviae in synovial fluid of baconers with chronic arthritis was studied at an abattoir. Cultural examination of synovial fluid samples from diseased tarsal joints of 50 animals from 42 herds yielded M. hyosynoviae in 10 cases from 8 herds. Streptococci were found in 6 cases from 6 other herds. M. hyosynoviae antigen was found in 1 of 47 of the samples, and antibody to the mycoplasma was found in 14 of 40 of the samples by ELISA test. The presence of M. hyosynoviae in a joint was usually accompanied by the corresponding antibody. In joints with streptococcal infection antibody to M. hyosynoviae could not be found.     

Sensitivity of Certain Porcine and Bovine Mycoplasmas to Antimicrobial Agents in a Liquid Medium Test Compared to a Disc Assay

The sensitivity of some porcine and bovine mycoplasmas to potent antimicrobial agents was examined. Minimal inhibitory concentration (MIC) values were estimated for M. hyosynoviae, M. hyopneumoniae, M. dispar and M. bovis against enrofloxacin, lincomycin, tetracycline, tiamulin and tylosin, in a liquid medium test and in a disc assay. All 6 examined strains of each species and the respective type strains were significantly inhibited. The greatest sensitivity was noted for tiamulin against strains of M. hyosynoviae with a final MIC₅₀ broth value of 0.025 µg ml⁻¹ and disc value of 0.03 µg per disc. Enrofloxacin was found very potent against M. hyopneumoniae with a final MIC₅₀ of 0.025 µg ml⁻¹ and 0.1 µg per disc, and for M. dispar with 0.05 µg ml⁻¹ and 0.03 µg per disc.Most disc assay estimates in ug per disc were similar to or moderately greater than corresponding final broth figures in µg ml⁻¹. It may be possible to convert observed disc assay values into representative final broth MIC values for use in the clinic.     

Airborne spread of foot-and-mouth disease – Model intercomparison

Foot-and-mouth disease virus (FMDV) spreads by direct contact between animals, by animal products (milk, meat and semen), by mechanical transfer on people or fomites and by the airborne route, with the relative importance of each mechanism depending on the particular outbreak characteristics. Atmospheric dispersion models have been developed to assess airborne spread of FMDV in a number of countries, including the UK, Denmark, Australia, New Zealand, USA and Canada. These models were compared at a Workshop hosted by the Institute for Animal Health/Met Office in 2008. Each modeller was provided with data relating to the 1967 outbreak of FMD in Hampshire, UK, and asked to predict the spread of FMDV by the airborne route.A number of key issues emerged from the Workshop and subsequent modelling work: (1) in general all models predicted similar directions for livestock at risk, with much of the remaining differences strongly related to differences in the meteorological data used; (2) determination of an accurate sequence of events on the infected premises is highly important, especially if the meteorological conditions vary substantially during the virus emission period; (3) differences in assumptions made about virus release, environmental fate and susceptibility to airborne infection can substantially modify the size and location of the downwind risk area. All of the atmospheric dispersion models compared at the Workshop can be used to assess windborne spread of FMDV and provide scientific advice to those responsible for making control and eradication decisions in the event of an outbreak of disease.