A scenario tree model for the Canadian Notifiable Avian Influenza Surveillance System and its application to estimation of probability of freedom and sample size determination

In 2008, Canada designed and implemented the Canadian Notifiable Avian Influenza Surveillance System (CanNAISS) with six surveillance activities in a phased-in approach. CanNAISS was a surveillance system because it had more than one surveillance activity or component in 2008: passive surveillance; pre-slaughter surveillance; and voluntary enhanced notifiable avian influenza surveillance. Our objectives were to give a short overview of two active surveillance components in CanNAISS; describe the CanNAISS scenario tree model and its application to estimation of probability of populations being free of NAI virus infection and sample size determination. Our data from the pre-slaughter surveillance component included diagnostic test results from 6296 serum samples representing 601 commercial chicken and turkey farms collected from 25 August 2008 to 29 January 2009. In addition, we included data from a sub-population of farms with high biosecurity standards: 36,164 samples from 55 farms sampled repeatedly over the 24 months study period from January 2007 to December 2008. All submissions were negative for Notifiable Avian Influenza (NAI) virus infection. We developed the CanNAISS scenario tree model, so that it will estimate the surveillance component sensitivity and the probability of a population being free of NAI at the 0.01 farm-level and 0.3 within-farm-level prevalences. We propose that a general model, such as the CanNAISS scenario tree model, may have a broader application than more detailed models that require disease specific input parameters, such as relative risk estimates.     

Neuro-imaging the serotonin 2A receptor as a valid biomarker for canine behavioural disorders

The serotonergic system is disturbed in different mood and affective disorders, with especially the serotonin (5-HT) 2A receptor involved in impulsive aggressiveness and anxiety. The aim of the study was to evaluate the involvement of the brain 5-HT 2A receptor in dogs with different behavioural disorders. Three groups of drug naive dogs were studied: 22 dogs showing impulsive aggressive behaviour, 22 showing normal behaviour, and 22 showing anxious behaviour. The serotonin 2A receptor was evaluated with Single Photon Emission Computed Tomography (SPECT) and the serotonin 2A receptor-selective radiopharmaceutical (123)I-R91150. A serotonin 2A receptor binding index (BI), proportional to the cortical receptor density, was calculated. A receiver operating characteristic (ROC) analysis was performed to determine cut-off values at which optimal sensitivity and specificity are achieved and to evaluate the general performance of the BI in reflecting the state of the dog, i.e., impulsive aggressive, normal or anxious. Significantly (P<0.0056) altered 5-HT 2A receptor binding indices were found in bilateral frontal, temporal and occipital cortical brain areas of the dogs behaving abnormally, with consistently increased BI in impulsive aggressive dogs and decreased BI in anxious dogs. These results provide clear evidence for a disturbed serotonergic balance in canine impulsive aggression and anxiety disorders. A right frontal cut-off value of ≥1.92 with 86.4% sensitivity and 2.3% (1-specificity) was obtained for the impulsive aggressive dogs. Differentiating the anxious dogs from the rest of the population was possible with a cut-off value of ≤1.73 with 86.4% sensitivity and 18.2% (1-specificity). We conclude that SPECT imaging with the radioligand (123)I-R91150 can be a helpful tool in evaluating the involvement of the serotonin 2A receptor in the complex mechanisms of impulsive aggressive and anxious behaviour. The 5HT-2A binding index of the right frontal cortex appears to be a valid biomarker in differentiating the studied canine behavioural disorders.     

In vitro inhibitory effect of trichostatin A on canine grade 3 mast cell tumor

Mast cell tumor (MCT) is one of the most prevalent neoplasms that affect skin and soft tissue in dogs. Because mast cell tumors present a great variety of clinical appearance and behavior, their treatment becomes a challenge. Trichostatin A (TSA), an antifungal antibiotic, has shown inhibitory effects on the proliferation and induction of apoptosis in various types of cancer cells. In order to evaluate the potential of trichostatin A as a therapeutic drug, cells of grade 3 MCT were cultured and treated with concentrations of 1 nM to 400 nM of TSA. MTT assay and trypan blue exclusion assays were performed to estimate cell growth and cell viability, and cell cycle analysis was evaluated. TSA treatment showed a reduction in numbers of viable cells and an increase of cell death by apoptosis. The cell cycle analysis showed an increase of hypodiploid cells and a reduction of G0/G1 and G2/M –phases. According to these results, trichostatin A may be an interesting potential chemotherapeutic agent for the treatment of canine MCT.     

Laparoscopic surgery in adult cattle.

Laparoscopy in cattle is a promising tool for clinical diagnosis and treatment. The lower cost of the materials available in addition to the possibility of an intervention on an animal that is sedated does not entail more costs than an exploratory laparotomy. The application of this tool during abdominal explorations and biopsies allows the avoidance of invasive and often useless surgical interventions and even with the diagnosis and prognosis of certain conditions. Surgical techniques currently are limited to abomasopexies; however, never-ceasing progress and improvements in human surgery are expected to affect the future of bovine surgery.With the advancements in the multimedia technology used by universities, the use of laparoscopy as a pedagogic tool definitely has a promising future. Endoscopic exploration of the thorax is possible using the same material as for laparoscopy. In addition, diagnostic and biopsy applications are useful. The use of the laparoscope in different body cavities and for different applications would make the purchase of the required materials more cost-effective.     

Horizontal Maedi-Visna virus (MVV) infection in adult dairy-sheep raised under varying MVV-infection pressures investigated by ELISA and PCR

A three year long experimental study was carried out to investigate horizontal MVV-infection by PCR and ELISA, in 191 one year-old latxa dairy-sheep raised in two separate groups under low and high MVV-infection pressure, respectively. Sheep originated from a previous MVV-transmission study in lambs and seroprevalence among one year-old sheep in both groups was 15% approximately. The high infection-pressure group (H-group) consisted of 147 replacement ewes that joined a milk-producing, housed dairy-flock with 42-66% MVV-seroprevalence and the low infection-pressure group (L-group) were castrated males raised in a separate shed. In contrast to results obtained when infection was investigated in lambs, the overall degree of agreement between ELISA and PCR results was very good and there was some indication that it increased further as sheep became older. MVV-prevalence did not change in the L-group and increased to 57% in three year-old sheep in the H-group (p<0.001). Random effects logistic regression confirmed seroconversion was significantly higher in the H-group compared to the L-group and was highest during the year after the sheep were introduced in the dairy flock and did not increase with age as in previous studies using less sensitive antibody assays. The evidence that horizontal transmission can be very low in spite of prolonged close contact between infected and non-infected sheep is valuable for MVV-control purposes. Furthermore it highlights the need to investigate virus excretion dynamics in infected animals and animal to animal transmission to improve our overall understanding of horizontal MVV transmission in MVV endemic populations.     

Dietary roughage sources affect lactating Holstein x Zebu cows under experimental conditions in Brazil: a meta-analysis

Tropical Animal Health and Production - To reduce costs, lactating cows are often fed a higher proportion of roughage and alternative feeds; however, such protocols may not lead to optimal milk...