Evaluation of shock waveform configuration on the defibrillation capacity of implantable cardioverter defibrillators in dogs

BackgroundImplantable cardioverter defibrillators (ICD) are programmed to detect ventricular arrhythmias and terminate them by delivering an electrical shock. A defibrillation threshold (DFT) at least 10 J below the maximum device output is recommended for successful therapy. Shock waveform configuration is a programmable parameter used to achieve a low DFT. It is hypothesized that a fixed-pulse configuration results in lower defibrillation energy requirements than a fixed-tilt configuration.Animals10 mongrel dogs.Materials and methodsICD generator and transvenous lead were surgically implanted. Defibrillation threshold was determined using a protocol guided by the upper limit of vulnerability. Fixed-pulse and fixed-tilt (50%/50%) waveform configurations were tested in a random order. Plasma cardiac troponin I (cTnI) was measured for signs of myocardial injury.ResultsThe experiment was completed in 9 dogs. Overall mean DFT value was 424 ± 88 V (9.2 ± 3.9 J). Mean differences among voltage, energy and impedance at the DFT for fixed-pulse (422 ± 97 V, 9.1 ± 4.2 J, 62.6 ± 13.8 Ω) and fixed-tilt (426 ± 83 V, 9.3 ± 3.8 J, 62.8 ± 18.5 Ω) configurations were not statistically significant (All P > 0.21). Cardiac TnI concentration changed from 0.03 ng/mL (95% CI: 0.02–0.04) at baseline to 0.11 ng/mL (95 CI: 0.08–0.16) after DFT was obtained with the first waveform configuration and 0.19 ng/mL (95% CI: 0.13–0.28) at the end of the study period. There were no significant changes in heart rate, end-tidal CO2 and blood pressure over time (all P > 0.09).ConclusionThe tested ICD device and lead placement reliably produced acceptable DFT values, based on a 10-J safety margin below the maximum device output. A benefit of fixed-pulse configuration could not be demonstrated over the standard fixed-tilt waveform. Signs of acute myocardial damage from repeated high-voltage shocks and episodes of ventricular fibrillation seemed of limited clinical significance.     

Characterization of CTLA-4, PD-1 and PDL-1 of swamp and riverine type water buffaloes

Characterization of CTLA-4, PD-1 and PDL-1 genes from swamp and riverine type water buffaloes was done by molecular cloning, sequencing and phylogenetic analysis. The cloned cDNA of CTLA-4, PD-1 and PDL-1 contained an open reading frame of 666, 849 and 870 nucleotides, encoding a polypeptide of 221, 282 and 298 amino acids, respectively. Nucleotide sequence homology of both CTLA-4 and PDL-1 had 99.8% in swamp and riverine type, which gives the identical polypeptide. Meanwhile, PD-1 genes of swamp and riverine type water buffaloes had 99.2% of homology in nucleotide sequence, which has substitution of two amino acid residues. The hexapeptide motif, phosphatidylinositol 3′-kinase and potential glycosylation sites were conserved within the tribe Bovinae. Phylogenetic analysis confirmed the degree of relationship between the bubaline species and justify the distinctness of each breeds by the bootstrap value generated.     

Investigation of the presence of ESBL-producing Escherichia coli in the North Wales and West Midlands areas of the UK in 2007 to 2008 using scanning surveillance

Between November 5, 2007 and November 4, 2008, faecal samples from cattle and sheep submitted for diagnostic purposes to the Aberystwyth and Shrewsbury Veterinary Laboratories Agency (VLA) (now AHVLA) regional laboratories (covering North Wales and the West Midlands) were screened for the presence of Escherichia coli that produces CTX-M extended-spectrum β-lactamase (ESBL) using the selective medium CHROMagar CTX. Samples from 113 farms were tested and eight ESBL-positive farms identified. Of these, six farms were identified via submissions of cattle faeces and two from sheep. Gene sequencing revealed both group 1 and group 9 CTX-M enzymes corresponding to CTX-M-14, CTX-M-14B (group 9) and CTX-M-15/28 (group 1). Analysis of these isolates by nanoarray revealed that some were carrying a range of virulence genes including ireA, iroN and prfB, which have been associated with extraintestinal pathogenic E coli, and were multidrug resistant. Geographical analysis with choropleth maps suggested that these CTX-M genes are relatively widespread in the North Wales and West Midlands study area. This work was carried out concurrently with the running of a VLA ESBL surveillance system, which has subsequently identified many more CTX-M positive farms in the UK.     

Laparoscopic cholecystectomy under field conditions in Asiatic black bears (Ursus thibetanus) rescued from illegal bile farming in Vietnam

Nine adult Asiatic black bears (Ursus thibetanus) previously rescued from illegal bile farming in Vietnam were examined via abdominal ultrasound and exploratory laparoscopy for liver and gall bladder pathology. Three bears demonstrated notable gall bladder pathology, and minimally invasive cholecystectomies were performed using an open laparoscopic access approach, standard 10 to 12 mmHg carbon dioxide pneumoperitoneum and a four-port technique. A single bear required insertion of an additional 5 mm port and use of a flexible liver retractor due to the presence of extensive adhesions between the gall bladder and quadrate and left and right medial liver lobes. The cystic duct was dissected free and this and the cystic artery were ligated by means of extracorporeal tied Meltzer knot sutures. The gall bladder was dissected free of the liver by blunt and sharp dissection, aided by 3.8 MHz monopolar radiosurgery. Bears that have had open abdominal cholecystectomies are reported as taking four to six weeks before a return to normal activity postoperatively. In contrast, these bears demonstrated rapid unremarkable healing, and were allowed unrestricted access to outside enclosures to climb trees, swim and interact normally with other bears within seven days of surgery.     

Ranking freshwater fish farms for the risk of pathogen introduction and spread

A semi-quantitative model is presented to rank freshwater rainbow trout farms within a country or region with regards to the risk of becoming infected and spreading a specified pathogen. The model was developed to support a risk-based surveillance scheme for notifiable salmonid pathogens. Routes of pathogen introduction and spread were identified through a process of expert consultation in a series of workshops. The routes were combined into themes (e.g. exposure via water, mechanical transmission). Themes were weighted based on expert opinion. Risk factors for each route were scored and combined into a theme score which was adjusted by the weight. The number of sources and consignments were used to assess introduction via live fish movements onto the farm. Biosecurity measures were scored to assess introduction on fomites. Upstream farms, wild fish and processing plants were included in assessing the likelihood of introduction by water. The scores for each theme were combined to give separate risk scores for introduction and spread. A matrix was used to combine these to give an overall risk score. A case study for viral haemorrhagic septicaemia is presented. Nine farms that represent a range of farming practices of rainbow trout farms in England and Wales are used as worked examples of the model. The model is suited to risk rank freshwater salmonid farms which are declared free of the pathogen(s) under consideration. The score allocated to a farm does not equate to a quantitative probability estimate of the farm to become infected or spread infection. Nevertheless, the method provides a transparent approach to ranking farms with regards to pathogen transmission risks. The output of the model at a regional or national level allows the allocation of surveillance effort to be risk based. It also provides fish farms with information on how they can reduce their risk score by improving biosecurity. The framework of the model can be applied to different production systems which may have other routes of disease spread. Further work is recommended to validate the allocated scores. Expert opinion was obtained through workshops, where the outputs from groups were single point estimates for relative weights of risks. More formal expert opinion elicitation methods could be used to capture variation in the experts' estimates and uncertainty and would provide data on which to simulate the model stochastically. The model can be downloaded (in Microsoft(?)-Excel format) from the Internet at: http://www.cefas.defra.gov.uk/6701.aspx.     

Patterns of rabies occurrence in Bhutan between 1996 and 2009

This study was conducted to evaluate incidence and seasonal trends of rabies in dogs and other domestic animals in Bhutan from 1996 to 2009. Time series analysis approach was used to determine the seasonal trend and temporal association between species-specific rabies cases in animals. A total of 814 rabies cases were reported during the 14-year period, of which cattle and domestic dogs accounted for 55% (447/814) and 39% (317/814) of the cases, respectively. The remaining 6% of the cases (50/814) were reported in horses (2%), cats (2%), pigs (1%) and goats (1%). Rabies cases were reported throughout the year with more reports during spring and summer months. The annual patterns of cases were stable from 1996 to 2005, but the incidence increased during 2006 and 2008. Fifty-nine of the 205 sub-districts reported rabies in animals from 1996 to 2009 with increased incidences in the four districts in southern Bhutan, an area located close to the border towns of India. A significant (P < 0.05) positive cross-correlation was observed between the number of cases in dogs and other domestic animals at time lags (months) 1-3 with the highest correlation (r = 0.94, P < 0.05) observed at time lag 0 (same month) indicating that the peak in rabies incidences occur in the same month when both dogs and other domestic animal cases are reported. Regression analysis predicted rabies in other domestic animal when there are reports of rabies in dogs during the previous months. This study provides useful information about the epidemiology of rabies that can be used to plan a rabies control programme in Bhutan.     

A prototype national cattle evaluation for sustained reproductive success in Hereford cattle

The objective of this research was to develop a prototype system for national cattle evaluation that would facilitate selection for improved fertility of daughters from Hereford sires. Raw data for this analysis were the birth dates of calves as reported by breeders to the American Hereford Association. Records from females entered this analysis with the reporting of a birth date for their first calf. At that time, females were required to be in contemporary groups of at least 3 animals and to have at least 2 additional paternal half-sibs also represented in the data. To explicitly define "sustained reproductive success," the philosophy taken was that a female that maintained a calving interval of 425 d or less would be considered successful. Females failing to meet this criterion were considered to be at the end of their successful lifetime. Data were analyzed using methodology for survival analysis with grouped data. Fixed contemporary groups were modeled as being time dependent, reflecting the females exposed for breeding in the same herd-year-season. Sire effects were time independent and considered random. Also included in the analysis were time-independent covariates for maternal weaning weight and total maternal calving ease from the national cattle evaluation of the American Hereford Association. Records from females still successfully in production at the time of this analysis, those that were transferred, those with calving intervals less than 280 d, and those that were successful until becoming donor dams for embryo transfer were considered censored. A total of 36,866 females contributed to this analysis, with 14,143 of these having censored records. The median number of females in a contemporary group was 6. A total of 3,323 sires had daughters with records. The median number of daughters per sire was 7. Heritability of sustained reproductive success on the underlying scale estimated from these data was approximately 0.05. Additional data accumulated over time will improve this genetic evaluation. Sustained reproductive success is important to the commercial beef industry, and results from this evaluation are expected to enhance the assessment of economic value of Hereford seedstock.     

Evaluation of miltefosine for the treatment of dogs naturally infected with L. infantum (=L. chagasi) in Brazil

Dogs naturally infected with Leishmania Infantum (=L. chagasi) were treated with miltefosine using different therapeutic regimens. The animals were evaluated for clinical evolution, biochemical parameters, parasite load (by real-time PCR), cytokine levels and humoral response. After treatment and during the following 24 months, there was progressive clinical improvement and complete recovery in 50% (7/14) of the treated animals. There was a decrease in the smear positivity of the bone marrow after treatment, and there was also a gradual and constant decrease in positive cultures at the end of the follow-up period. However, the PCR detection of parasite DNA remained positive. In general, all animals presented a significant increase in parasite load 6 months after treatment. The IFN-γ levels in all the groups tended to increase during follow-up period, regardless of the miltefosine dose administered. The IL-4 and IL-10 levels of the animals tended to decrease during follow-up, except after 300 days when only IL-10 increased. The serum antibodies identified antigens that ranged from 116 kDa to less than 29 kDa in the Western blot assay. Furthermore, 300 days after treatment, qualitative and quantitative differences in the antigen profiles were observed. Antigens of 97 and 46 kDa were the most intensely recognized. Higher levels of antigen-specific Leishmania IgG were detected before and 300 days after treatment in all groups. Taking together, the improvement in the clinical symptoms was not followed by parasitological clearance, suggesting that treatment with miltefosine is not recommended, especially in endemic areas like Brazil, where children are the major victims and dogs are involved in the maintenance of the parasite cycle.     

Equine hospital data as a source for study of prevalence and heritability of osteochondrosis and palmar/plantar osseous fragments of Swedish Warmblood horses

Reasons for performing study: Disturbances in skeletal development, primarily osteochondrosis (OC) and palmar/plantar osseous fragments (POF), have been commonly reported as problems in young horses. However, there are few reports of such findings for epidemiological analyses or breeding purposes. Objectives: To evaluate equine hospital data as a possible source of information for genetic evaluations by estimating prevalence and heritability of OC in the stifle, hock and fetlock joints and of POF in the fetlock. Methods: Data on Swedish Warmblood (SWB) horses were obtained from a large equine hospital in south Sweden. Prevalences were based on radiographic examinations of 879 screened horses, mainly evaluated as part of a prepurchase examination and 3639 horses with a reported history of orthopaedic problems. For the heritability study the 2 data sources were pooled and 3199 examined horses with pedigree information were considered for the linear animal model analyses. Results: The overall prevalence of OC was 13% (stifle 9%, hock 6% and dorsal osseous fragments in fetlock [DOF] 10%) and POF 10%. The overall heritability of OC was 0.05 on the visible binomial scale. The corresponding heritabilities for OC in the stifle were 0.03, hock 0.08, DOF 0.10 and POF 0.13. These values correspond to heritabilities of 0.09–0.38 on the underlying quantitative scale. Conclusions and potential relevance: Obtained prevalences and heritabilities were in accordance with other studies, supporting the hypothesis that data regularly obtained from equine hospitals may be a valuable source in studies of inherited disorders such as OC and POF. There is a need for more standardised documentation of diagnoses and consistent recording of identity of examined horses using passports or breed databases. Compilation of results from major clinics is desired in order to cover most progenies of stallions used in a region or nation.     

Comparative study between atropine and hyoscine-N-butylbromide for reversal of detomidine induced bradycardia in horses

Reasons for performing study: Bradycardia may be implicated as a cause of cardiovascular instability during anaesthesia. Hypothesis: Hyoscine would induce positive chronotropism of shorter duration than atropine, without adversely impairing intestinal motility in detomidine sedated horses. Methods: Ten minutes after detomidine (0.02 mg/kg bwt, i.v.), physiological saline (control), atropine (0.02 mg/kg bwt) or hyoscine (0.2 mg/kg bwt) were randomly administered i.v. to 6 horses, allowing one week intervals between treatments. Investigators blinded to the treatments monitored cardiopulmonary data and intestinal auscultation for 90 min and 24 h after detomidine, respectively. Gastrointestinal transit was assessed for 96 h via chromium detection in dry faeces. Results: Detomidine significantly decreased heart rate (HR) and cardiac index (CI) from baseline for 30 and 60 min, respectively (control). Mean ± s.d. HR increased significantly 5 min after atropine (79 ± 5 beats/min) and hyoscine (75 ± 8 beats/min). After this time, HR was significantly higher after atropine in comparison to other treatments, while hyoscine resulted in intermediate values (lower than atropine but higher than controls). Hyoscine and atropine resulted in significantly higher CI than controls for 5 and 20 min, respectively; but this effect coincided with significant hypertension (mean arterial pressures >180 mmHg). Auscultation scores decreased from baseline in all treatments. Time to return to auscultation scores ≥12 (medians) did not differ between hyoscine (4 h) and controls (4 h) but atropine resulted in significantly longer time (10 h). Atropine induced colic in one horse. Gastrointestinal transit times did not differ between treatments. Conclusion: Hyoscine is a shorter acting positive chronotropic agent than atropine, but does not potentiate the impairment in intestinal motility induced by detomidine. Because of severe hypertension, routine use of anticholinergics combined with detomidine is not recommended. Potencial relevance: Hyoscine may represent an alternative to atropine for treating bradycardia.