A model of the relationship between the epidemiology of Johne's disease and the environment in suckler-beef herds

A non-predictive, dynamic and stochastic herd-level simulation model of an outbreak of Johne's in a suckler-beef herd is reported. Importantly, the model incorporates, with a simple method, the environment as the primary source of infection, reflecting the consensual understanding of the disease. The model also takes into account the density of the infectious agent in the environment. A sensitivity analysis suggests that the model is highly and equally sensitive to certain parameters (probability of infection in the presence of one unit of bacterial density, infectious area and bacterial shedding rate). Mathematical reasons for this similarity in sensitivity are presented. Compared to many other diseases, data for Johne's are scarce. Therefore models of Johne's outbreaks including this one cannot be predictive or easily validated. The qualitative results: (a) demonstrate the modelled effect of inclusion of infection via the environment; (b) suggest management factors that could be tested by experimentation or observation. Estimates for the rate of transmission, arising from the model output, are similar to published empirical estimates. The results of future empirical research should aid scientific understanding of the disease, help validate this model and might bring economic benefits through improved management.     

Investigations of cattle herd breakdowns with bovine tuberculosis in four counties of England and Wales using VETNET data

Cattle herd breakdown (HBR) with bovine tuberculosis (BTB) was investigated for farms in four counties of England and Wales outside southwest England from 1986 to early 2000. Data from the national database of TB testing history (VETNET) were used. Factors that influenced HBR included calendar time, herd size, number of cattle tested, the test type, the inter-test interval and spatial grouping of farms. Herd tests other than routine herd tests had an increased risk of HBR in all four counties. In all counties, the risk of HBR increased with calendar time and in Shropshire a test interval of 3 years was associated with an increased risk of HBR compared with a 1-year test interval. In Staffordshire and Sussex, a 4-year test interval was associated with a lower risk of HBR compared with a 1-year test interval. There was no evidence of spatial clustering of HBR in West Glamorgan (equal spatial risk in a 15–30 km radius) and weak evidence of spatial clustering in Shropshire (7–15 km) and Sussex (5–10 km). In Staffordshire, there was evidence of spatial (2–4 km) and time (3–4 years) clustering of HBR. The locally increased rate of testing following a confirmed HBR increased the detection of infected herds but did not prevent local spread in two of the four counties (Shropshire and Staffordshire) since the rate of HBR increased linearly from 1988 to 2000. The main conclusion is that there were both local and distant components of spread.     

Prevalence of intercurrent disease in dogs and cats presented for vaccination at a veterinary practice

A prospective study was undertaken to determine the prevalence of intercurrent disease in dogs and cats presented for vaccination in general practice. Fifty-two percent of animals were found to suffer from intercurrent disease and 3% had severe debilitating disease. A thorough clinical examination conducted at the time of routine vaccination appears to be an important element in maintaining companion animal health and welfare.     

Considerations for analysis of time-to-event outcomes subject to competing risks in veterinary clinical studies

In veterinary medicine, prospective clinical trials are increasingly utilized to address questions regarding effectiveness of therapies and patient prognosis. A large number of these trials involve time-to-event (TTE) endpoints, which require special methods of analysis to handle data in which not all subjects are observed to have the event of interest. Analyses and interpretation of the results can be further complicated when an endpoint of interest is not observed in some patients because they incur a competing risk, such as death from an unrelated cause. Competing risks have been the source of confusion in many epidemiologic analyses leading to the potential for misinterpretation. In this article, we review key considerations for the TTE analysis in the setting of competing risks. We briefly review standard TTE tools, namely Kaplan–Meier survival curves and Cox regression. In the setting of outcomes with competing risks, we provide guidance on the appropriate analysis techniques, such as cumulative incidence curves, to estimate the risk of an event of interest. We also describe a common pitfall of treating competing risks as censoring in Kaplan–Meier survival curve analysis, which can overestimate the event rate of interest. We describe two common regression methods that examine associated risk factors in the presence of competing risks and highlight the different research questions these methods address. This article provides an introductory overview and illustrates concepts with examples from veterinary trials and with example data sets.     

Evidence-based veterinary dentistry: a systematic review of homecare for prevention of periodontal disease in dogs and cats

Successful treatment and prevention of periodontal disease in pet animals requires a multidimensional approach to identify and eliminate exacerbating factors, provide scheduled professional examinations and care, and plan and implement a dental homecare program. Over the years, many therapeutic and preventive interventions have been developed or advocated for periodontal disease, but evidence of efficacy or effectiveness is highly variable. Accordingly, the main objective of this systematic review is to identify and critically appraise the evidence supporting various aspects of homecare for prevention of canine and feline periodontal disease.     

Expenditures for veterinary services and other costs of disease and disease prevention in 57 California beef herds in the National Animal Health Monitoring System (1988-1989)

Data on costs associated with episodes of disease and disease prevention, including expenditures for veterinary services, were collected from 57 California beef cow-calf herds during 1988-1989 as part of the National Animal Health Monitoring System. Mean cost associated with episodes of disease was $33.90/cow-year, with $0.78 and $1.37/cow-year being spent for veterinary services and drugs, respectively. The highest cost for veterinary services related to episodes of disease were for dystocia, lameness, and ocular carcinoma. For disease prevention, mean expenditures for veterinary services were $1.67/cow-year, nearly all of which was spent on prevention of reproductive tract conditions. Preventive expenditures for veterinary services related to female infertility (pregnancy examination), vaccination against brucellosis and male infertility (breeding soundness examination) were $0.72, $0.39, and $0.22/cow-year, respectively. Many costs associated with episodes of disease and disease prevention were similar to those reported from Colorado National Animal Health Monitoring System beef herds.     

RESEARCH PAPER: Comparison of two different methods for physiologic dead space measurements in ventilated dogs in a clinical setting

ObjectiveTo compare physiologic dead space (V_D) and physiologic dead space to tidal volume (V_T) ratio (V_D/V_T) obtained by an automated single breath test for carbon dioxide (CO₂) (method SBT) and a manual calculation (method MC) in ventilated healthy dogs.Study designProspective clinical study.AnimalsTwenty client‐owned dogs, ASA I and II undergoing anaesthesia for clinical purposes.MethodsFollowing pre‐medication, induction of anaesthesia, and intubation of the trachea, intermittent positive pressure ventilation was commenced. Mixed expired CO₂ partial pressure (PēCO₂) was measured by two methods: method MC by analysis, using an infrared capnograph, of the expired gas collected in a mixing box and method SBT which calculated it automatically by a device consisting of a mainstream capnograph and a pneumotachograph. At four time points arterial partial pressure of CO₂ (PaCO₂) was measured. Physiologic dead space variables (V_D and V_D/V_T) were calculated manually (method MC) or automatically (method SBT) using the Bohr–Enghoff equation.Method MC and SBT were compared using Bland–Altman plots and linear regression. Intra‐class correlation coefficient (ICC) was used to measure consistency of each method.ResultsFour measurement pairs were obtained in all 20 dogs for method SBT and MC. The bias was ?1.15 mmHg, 7.97 mL and 0.02 for PēCO₂, V_D and V_D/V_T, respectively. Linear regression analysis revealed a correlation coefficient (r²) of 0.79, 0.94, and 0.83 for PēCO₂, V_D and V_D/V_T, respectively. The ICC revealed an excellent consistency for both methods.ConclusionsThe single breath test (SBT) can be used for clinical evaluation of V_D and V_D/V_T in anaesthetized ventilated dogs.Clinical relevanceThrough measuring V_D and V_D/V_T important information about lung ventilation can be obtained and the SBT is an easy method to use for this purpose.     

Linking causal concepts, study design, analysis and inference in support of one epidemiology for population health

In this paper, which is dedicated to Dr. Calvin Schwabe, I review the concepts of causation and how they impact on study design, analysis and interpretation of results. Notwithstanding the fact that no observational study can prove causation, there are a number of issues that if addressed sufficiently, can improve the validity and usefulness of our studies. These are elaborated with specific recommendations for the conduct of future observational research. Approaches that have been useful in my teaching and research experience are also described.     

Evaluation of Ziehl–Neelsen stained faecal smear and ELISA as tools for surveillance of clinical paratuberculosis in cattle in the Netherlands

Testing cattle suspected of clinical paratuberculosis is an important element of surveillance of paratuberculosis. The aim of this study was to evaluate the diagnostic-test characteristics of microscopic examination of Ziehl–Neelsen stained faecal smears for acid-fast Mycobacteria (ZN-test) and serum-ELISA in cattle suspected of clinical paratuberculosis in the Netherlands.Results of all samples submitted for ZN-test and serum-ELISA between April 2003 and April 2006 to our laboratory were retrieved. Results from cattle for which both tests were performed were analysed using two Bayesian latent-class models for evaluation of diagnostic tests in two populations without a gold standard, assuming (a) conditional independence of tests, or (b) conditional dependence of tests in both infected and non-infected cattle. Sampled cattle were divided into two populations in different ways using four known risk factors for clinical paratuberculosis: region, soil type, clinical signs, and age.For 892 cattle suspected of clinical paratuberculosis, both ZN-test and serum-ELISA results were retrieved: 250 ZN-positive and ELISA-positive, 12 ZN-positive and ELISA-negative, 260 ZN-negative and ELISA-positive, and 370 ZN-negative and ELISA-negative cattle.With priors based on the available literature, the posterior estimates of sensitivity, specificity, and positive and negative predictive values of the ELISA were always higher than those of the ZN-test. Furthermore, lower limits of the 95% credibility intervals of the posterior positive predictive values of the ELISA were ≥99.7%, and of the negative predictive values of the ELISA ≥56.4%.We conclude that the ELISA is preferred to the ZN-test to confirm the presumptive diagnosis of clinical paratuberculosis in the Netherlands. Little diagnostic information can be gained by performing the ZN-test in addition to the ELISA.     

3种根茎型禾草无性繁殖时空扩展初探

以青海扁茎早熟禾Poa pratensis var. anceps cv.Qinghai、草原看麦娘Alopecurus pratensis、无芒雀麦Bromus inermis 3种根茎型禾草为材料,进行无性繁殖,并从地上和地下部分比较了3种根茎型禾草无性繁殖的时空扩展情况.结果表明:3种根茎型禾草分蘖株数、根茎数、侵占面积随着生长时间的增加存在显著差异(P<0.05),移植当年青海扁茎早熟禾分蘖株数可达68个/株、根茎数可达24个/株、侵占面积可扩展到731.2 cm2;分别较草原看麦娘多12个/株、2个/株、91.1 cm2;分别较无芒雀麦多22个/株、5个/株、321.9 cm2.3种根茎型禾草移植当年均能成熟,其中青海扁茎早熟禾成熟最早,草原看麦娘次之,无芒雀麦最晚,时空扩展速度表现为青海扁茎早熟禾>草原看麦娘>无芒雀麦.3种根茎型禾草分蘖株数与侵占面积之间呈线性关系,根茎平均长度与侵占面积呈指数关系.     

Confidence limits for prevalence of disease adjusted for estimated sensitivity and specificity

Prevalence of a disease is usually assessed by diagnostic tests that may produce false results. Rogan and Gladen (1978) described a method to estimate the true prevalence correcting for sensitivity and specificity of the diagnostic procedure, and Reiczigel et al. (2010) provided exact confidence intervals for the true prevalence assuming sensitivity and specificity were known. In this paper we propose a new method to construct approximate confidence intervals for the true prevalence when sensitivity and specificity are estimated from independent samples. To improve coverage we applied an adjustment similar to that described in Agresti and Coull (1998). According to an extensive simulation study the new confidence intervals maintain the nominal level fairly well even for sample sizes as small as 30; minimum coverage is above 88%, 93%, and 98% at nominal 90%, 95%, and 99%, respectively. We illustrate the advantages of the proposed method with real-life applications.     

On accuracy and precision of flowmeters used for oxygen therapy in a veterinary teaching hospital

Objective

To determine the accuracy and precision of flowmeters used for oxygen therapy in a veterinary teaching hospital.

Measurement of tear production in black‐tufted marmosets (Callithrix penicillata) using three different methods: modified Schirmer’s I,phenol red thread and standardized endodontic absorbent paper points

Objective: To report normal tear production of healthy adult black‐tufted marmosets and propose a novel alternative for the measurement of the aqueous portion of tear production in animals with small eyes. Animal studied: Black‐tufted marmosets (Callithrix penicillata). Procedures: Tear production of 19 animals was evaluated by the following methods: modified Schirmer’s I, phenol red thread and the novel use of standardized endodontic absorbent paper points. These methods and results were compared. Additionally, blink frequency and palpebral fissure length were measured. Results: Modified Schirmer’s test I, mean = ?0.46 ± 3.41 mm/min; Phenol red thread, mean = 13.27 ± 5.41 mm/15 s.; Standardized endodontic paper points, size 30, mean = 9.32 ± 3.09 mm/min; Mean palpebral fissure length = 7.83 ± 0.72 mm. Blink frequency, mean = 20.27 ± 5.92/5 min. Conclusions: Normal parameters for blink frequency, palpebral fissure length and tear production measurement are presented. The palpebral fissure of black‐tufted marmoset is very small and tear production is one of the lowest reported for all animal species. A novel and practical alternative for tear production measurement using standardized endodontic absorbent paper points is presented and is indicated for animals with small eyes.     

近42年榆中县气温突变及周期变化

利用榆中县1971-2012年的日平均气温,采用线性倾向率法、累积距平法、Mann-Kendall法和小波分析等方法,对榆中县42年来的温度变化和突变现象进行了研究。结果表明,近42年来,榆中县年平均气温变化在5.73~8.04℃,年平均气温呈现升高趋势,气候倾向率为0.26℃·10a~(-1),并且榆中县年平均气温突变出现在1995―1996年;榆中县四季平均气温表现为相同趋势,其中冬季的气候倾向率达到0.28℃·10a~(-1),增幅最明显;春季次之,为0.25℃·10a~(-1)。28a时间尺度是榆中年平均气温的第一主周期,同时还有14和6a时间尺度变化周期。榆中县气温呈上升趋势,且呈一定的周期和规律变化。     

The function, composition and analysis of cerebrospinal fluid in companion animals: part I - function and composition

Cerebrospinal fluid (CSF) is a clear, colourless ultrafiltrate of plasma with low protein content and few cells. The CSF is mainly produced by the choroid plexus, but also by the ependymal lining cells of the brain's ventricular system. CSF flows through the ventricular system and then into the subarachnoid space and it is subsequently absorbed through the subarachnoid villi into the venous system. CSF has several functions in the nervous system. It protects the brain during blood pressure fluctuations, regulates the chemical environment of the central nervous system and it is a vehicle for intracerebral transport. This two-part article reviews CSF function, physiology, analytical techniques and interpretations in disease states of companion animals. This first part will address the function and composition of CSF in companion animals.     

东北地区部分细毛羊羊毛品质检测分析

为了深入了解东北地区细毛羊的羊毛品质状况,更好地开展细毛羊品种选育与推广工作,试验进行了东北部分地区细毛羊毛样的长度、长度离散度、细度、细度离散度、净毛率、油脂含量、色度以及部分毛样的毛尖、毛中、毛根细度检测及羊毛品质分级。结果表明:所测毛样组成为细羊毛(71.97%)、半细羊毛(2.28%)、等外级(7.19%)和超细型(18.56%)4类。说明东北地区拥有符合细羊毛纺织标准的当地细毛羊品种和符合高档毛纺原料需求的超细型细毛羊种群,同时广泛分布着以毛肉兼用为主的细毛羊生产群。     

适宜动物饲料化利用的北方桑树品种筛选及收获技术研究

从桑树存活率、单株条数、叶条收获量、叶条品质和叶条比5个方面探讨不同桑树品种用于开发动物饲料的适宜性,为筛选适宜动物饲料化利用的桑树品种提供参考。经连续5年试验,发现所用杂交桑品种比嫁接桑品种存活率高、发条数多、收获量大,更适宜用作动物饲料。合理的桑条收获方式是:根据饲喂动物的营养需求和能量需求,结合桑树的生长状况,确定收获时期;根据桑树品种及栽植地气候环境条件,按照用树与养树相结合的原则,确定每年的收获次数。     

猪场猪瘟、伪狂犬病免疫程序调整的可行性分析

为避免按不合理的免疫程序接种后给母猪的生产和仔猪的生长发育等带来负面影响,如仔猪应激,妊娠母猪流产及胚胎死亡等,金华种猪场以抗体测定为依据对猪瘟、伪狂犬病的免疫接种效果作了相应的试验后得出:后备母猪在配种前３周接种猪瘟疫苗,１５０日龄和２００日龄接种伪狂犬病疫苗;母猪在断奶时接种猪瘟疫苗,产前３周接种伪狂犬病疫苗;仔猪分别在２１日龄和５０~６０日龄接种猪瘟疫苗。