Inter-laboratory and inter-assay comparison on two real-time PCR techniques for quantification of PCV2 nucleic acid extracted from field samples

Several real-time PCR assays for quantification of PCV2 DNA (qPCR) have been described in the literature, and different in-house assays are being used by laboratories around the world. A general threshold of 10(7) copies of PCV2 per millilitre serum for postweaning multisystemic wasting syndrome (PMWS) diagnosis has been suggested. However, neither inter-laboratory nor inter-assay comparisons have been published so far. In the present study, two different qPCR probe assays used routinely in two laboratories were compared on DNA extracted from serum, nasal and rectal swabs. Results showed a significant linear association between the assays (p<0.0001), and a systematic difference of 1.4 log10 copies of PCV2 per millilitre of sample (p<0.0001). This difference indicated that the assay from laboratory 1 yielded a higher output than the one from laboratory 2. Results also showed that there was no linear association between the amount of PCV2 DNA and the amount of total DNA, neither in nasal (p=0.86) nor in rectal (p=0.78) swabs, suggesting that normalizing of PCV2 DNA load in swab samples to total DNA concentration is not suitable. The present exploratory study highlights the need for the performance of ring trials on qPCV2 protocols between laboratories. Meanwhile, the proposed thresholds for PMWS diagnosis should only be considered reliable for each particular laboratory and each particular assay.     

Phospholipid compositions of sera and synovial fluids from dog, human and horse: a comparison by 31P-NMR and MALDI-TOF MS

Alterations of the phospholipid (PL) compositions of body fluids are assumed to be indicative of inflammatory diseases, e.g. rheumatoid arthritis (RA). Recently, we have shown that particularly the phosphatidylcholine/lysophosphatidylcholine (PC/LPC) ratio determined in human synovial fluids (SF) and sera represents a reliable measure of the inflammatory state in RA patients. However, it is not yet clear to what extent the PC/LPC ratio is also affected by nutrition habits. In the present study, the PL and the corresponding acyl chain compositions of human body fluids (SF and serum of RA patients as well as serum from healthy volunteers) are compared with those of two other mammalian species (horses and dogs suffering from degenerative joint diseases as well as healthy controls) by high-resolution 31P-nuclear magnetic resonance (NMR) spectroscopy and matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS). The most important result of this study is that the PL compositions of SF and serum of horse and dog are comparable with those of human body fluids. Compared with humans, however, the horse body fluid contains less PCs with highly unsaturated arachidonoyl residues, while that of dogs possesses the highest content of arachidonoyl-containing PC. These species-related differences stem primarily from different nutrition habits (meat vs. plants).     

The pharmacokinetics and metabolism of ivermectin in domestic animal species

The pharmacokinetic properties of drugs are closely related to their pharmacological efficacy. The kinetics of ivermectin are characterised, in general terms, by a slow absorption process, a broad distribution in the organism, low metabolism, and slow excretion. The kinetics vary according to the route of administration, formulation, animal species, body condition, age, and physiological status, all of which contribute to differences in drug efficacy. Characterisation of ivermectin kinetics can be used to predict and optimise the value of the parasiticide effects and to design programmes for parasite control. This article reviews the pharmacokinetics of ivermectin in several domestic animal species.     

Drivers and risk factors for circulating African swine fever virus in Uganda, 2012–2013

We explored observed risk factors and drivers of infection possibly associated with African swine fever (ASF) epidemiology in Uganda. Representative sub-populations of pig farms and statistics were used in a case-control model. Indiscriminate disposal of pig viscera and waste materials after slaughter, including on open refuse dumps, farm-gate buyers collecting pigs and pig products from within a farm, and retention of survivor pigs were plausible risk factors. Wire mesh-protected windows in pig houses were found to be protective against ASF infection. Sighting engorged ticks on pigs, the presence of a lock for each pig pen and/or a gate at the farm entrance were significantly associated with infection/non-infection; possible explanations were offered. Strict adherence to planned within-farm and community-based biosecurity, and avoidance of identified risk factors is recommended to reduce infection. Training for small-scale and emerging farmers should involve multidimensional and multidisciplinary approaches to reduce human-related risky behaviours driving infection.     

Factors associated with morbidity,mortality, and growth of dairy heifer calves up to 3 months of age

Calfhood disease is an important problem on many dairy operations that can have substantial effects on heifer survival and productivity, and has economic and welfare impacts. Neonatal calf diarrhea (NCD) and bovine respiratory disease (BRD) are the most common causes of morbidity and mortality in young dairy cattle. The objective of this observational study was to investigate factors associated with the risks of morbidity and mortality, and with growth, in commercial dairy heifers calves. A total of 2874 heifer calves from 19 commercial dairy farms in Minnesota and Ontario were enrolled at 1–7 days of age and followed for approximately 3 months. Using cut-points of serum total protein of 5.2 and 5.7 g/dl, the incidences of failure of transfer of passive immunity (FTPI) were 11 and 32%, respectively. A cut-point of 5.7 g/dl was the most predictive of BRD before 5 weeks of age (sensitivity = 40%, specificity = 69%). The positive predictive value was poor (PPV = 18%), but the negative predictive value was good (NPV = 87%). A cut-point of 5.2 g/dl was most predictive of death before 5 weeks of age (sensitivity = 27%, specificity = 89%, PPV = 5%, NPV = 98%). Serum total protein during the first week of life was a poor predictor of NCD. Over 23% of calves were treated for diarrhea. Risk factors were weight at enrollment, other diseases before 2 weeks of age, and an interaction between season of birth and herd-level incidence of NCD. Almost 22% of calves were treated at least once for BRD. Factors associated with an increased risk of BRD included herd-level incidence of BRD, season of birth, navel dipping, other diseases before 2 weeks of age, failure of transfer of passive immunity, and manual control of temperature in pre-weaning housing. Administration of supplemental antibody products at birth was associated with a reduced incidence of BRD. Overall mortality was 3.5%. Risk of mortality was increased by treatment for BRD and other diseases. The mean average weight gain was 0.95 kg/day (range: 0.11–1.62 kg/day; SD = 0.2). Twinning status, FTP, treatment for NCD or other diseases, and month of birth influenced body weight. This study illustrated relationships among various diseases, mortality, and growth. Furthermore, it demonstrated the importance of colostrum for protection against BRD and improved growth performance, while bringing into question the optimal method of determining failure of transfer of passive immunity.     

A multi-analysis approach for space–time and economic evaluation of risks related with livestock diseases: The example of FMD in Peru

This study presents a multi-disciplinary decision-support tool, which integrates geo-statistics, social network analysis (SNA), spatial-stochastic spread model, economic analysis and mapping/visualization capabilities for the evaluation of the sanitary and socio-economic impact of livestock diseases under diverse epidemiologic scenarios. We illustrate the applicability of this tool using foot-and-mouth disease (FMD) in Peru as an example. The approach consisted on a flexible, multistep process that may be easily adapted based on data availability. The first module (mI) uses a geo-statistical approach for the estimation (if needed) of the distribution and abundance of susceptible population (in the example here, cattle, swine, sheep, goats, and camelids) at farm-level in the region or country of interest (Peru). The second module (mII) applies SNA for evaluating the farm-to-farm contact patterns and for exploring the structure and frequency of between-farm animal movements as a proxy for potential disease introduction or spread. The third module (mIII) integrates mI–II outputs into a spatial-stochastic model that simulates within- and between-farm FMD-transmission. The economic module (mIV) connects outputs from mI–III to provide an estimate of associated direct and indirect costs. A visualization module (mV) is also implemented to graph and map the outputs of module I–IV. After 1000 simulated epidemics, the mean (95% probability interval) number of outbreaks, infected animals, epidemic duration, and direct costs were 37 (1, 1164), 2152 (1, 13, 250), 63 days (0, 442), and US$ 1.2 million (1072, 9.5 million), respectively. Spread of disease was primarily local (<4.5 km), but geolocation and type of index farm strongly influenced the extent and spatial patterns of an epidemic. The approach is intended to support decisions in the last phase of the FMD eradication program in Peru, in particular to inform and support the implementation of risk-based surveillance and livestock insurance systems that may help to prevent and control potential FMD virus incursions into Peru.     

Aldicarb poisoning of dogs and cats in Gauteng during 2003

A survey of aldicarb poisoning in companion animals was conducted by posting questionnaires to all private practitioners in Gauteng Province, South Africa. The survey was designed to determine the percentage of aldicarb cases seen, treatment regimen, clinical signs observed, proposals for preventative actions and more effective treatments. Other questions included duration of treatment, survival rate, cost to clients, post mortem findings and reasons for poisonings.