Issues of reporting in observational studies in veterinary medicine

Observational studies are common in veterinary medicine; the results may be used to inform decision-making, future research, or as inputs to systematic reviews or risk assessment. To be of use, the results must be published, all of the outcomes that were assessed must be included in the publication, and the research (methods and results) must be reported in sufficient detail that the reader can evaluate the internal and external validity. In human healthcare, concerns about the completeness of reporting – and evidence that poor reporting is associated with study results – have led to the creation of reporting guidelines; these include the STROBE statement for observational studies.     

Understanding and evaluating veterinary clinical research

Results from investigations conducted in clinical settings contribute greatly to determining how veterinarians practice medicine. It is important for the practitioner to understand how clinical information is collected, analyzed, and communicated in journals and presentations at conferences. Clinical research is either retrospective in observational studies, looking at historical medical records as the source of data, or prospective in both experimental and observational studies, where the study is designed before any patients are included. Prospective, experimental studies provide the more reliable results, although they form a minority of published reports. Randomized, controlled trials are the most reliable format, and attempts should be made to use this design more often in veterinary medicine. Care must be taken in the conduct of clinical research to reduce sources of bias that can yield false findings, particularly in small, retrospective studies. Statistical analysis is the key to data interpretation, but must be applied appropriately to avoid either wrong assumptions or misconception. Regardless of how studies are conducted, it is important for the practitioner to be an astute reader of the clinical literature. An understanding of clinical research methods will result in better medical standard of care recommendations and practice.     

Illness Severity Scores in Veterinary Medicine: What Can We Learn?

Illness severity scores are gaining increasing popularity in veterinary medicine. This article discusses their applications in both clinical medicine and research, reviews the caveats pertaining to their use, and discusses some of the issues that arise in appropriate construction of a score. Illness severity scores can be used to decrease bias and confounding and add important contextual information to research by providing a quantitative and objective measure of patient illness. In addition, illness severity scores can be used to benchmark performance, and establish protocols for triage and therapeutic management. Many diagnosis‐specific and diagnosis‐independent veterinary scores have been developed in recent years. Although score use in veterinary research is increasing, the scores available are currently underutilized, particularly in the context of observational studies. Analysis of treatment effect while controlling for illness severity by an objective measure can improve the validity of the conclusions of observational studies. In randomized trials, illness severity scores can be used to demonstrate effective randomization, which is of particular utility when group sizes are small. The quality of veterinary scoring systems can be improved by prospective multicenter validation. The prevalence of euthanasia in companion animal medicine poses a unique challenge to scores based on a mortality outcome.     

Risk factors associated with behavioural disorders of crib-biting,weaving and box-walking in Swiss horses

REASONS FOR PERFORMING STUDY: Studies on the prevalence of behavioural disorders in horses and on associated risk factors have revealed inconsistent results. There are many studies on the neuropharmacological, surgical or mechanical therapy of stereotypies, but little is known about their causation. OBJECTIVES: To explore risk factors associated with the occurrence of behavioural disorders in horses. METHODS: A sample of horse owners, selected randomly and representative for Switzerland, was contacted in a postal survey. Answers were provided for 622 stables (response rate 35.2%). Individual data of 2,341 horses were examined with path analysis (multivariable linear and logistic regression), and adjustment made for possible confounding effects due to age and breed. RESULTS: Out of 60 possible risk factors, 11 were associated with the outcome at the univariable level (null-hypothesis path model) and 3 factors remained after the backward logistic regression procedure. Mature Warmbloods and Thoroughbreds, assessed by the owners to be reactive, fed 4 times a day and without daily pasture, had increased odds of displaying crib-biting, weaving and box-walking. Furthermore, indirect associations of 5 factors with the outcome were identified. CONCLUSIONS: The final logistic regression model of risk factors leads to the hypotheses that causal prevention of stereotypic behaviours should be based upon housing and management conditions which allow tactile contact with other horses (e.g. mutual grooming), daily free movement (paddock or pasture), as well as the provision of high amounts of roughage but of little or no concentrates. POTENTIAL CLINICAL RELEVANCE: It is one of the aims of population medicine to prevent the development of behavioural disorders. Further research is needed to test the concluding hypotheses in experimental studies or to verify them in the context of similar observational studies.     

Reflections on scrapie and related disorders,with consideration of the possibility of a viral aetiology

The transmissible spongiform encephalopathies of domesticated animals, scrapie in-sheep and bovine spongiform encephalopathy (BSE), and transmissible mink encephalopathy are more than a scientific curiosity; under certain circumstances their impact on commercial activities can be calamitous. Knowledge of their causation and pathogenesis is still rudimentary, but many consider than an unconventional agent, the prion (a brain protein, PrP), that is not associated with nucleic acid is involved in both. Others believe that conventional viruses, which replicate by virtue of their nucleic acid-defined genes, are involved in the causation and progression of the encephalopathies but that technical problems have prevented their identification. Others postulate even more exotic causative agents. While this paper will particularly address the possibility of a viral aetiology for these diseases, it is also emphasized that our knowledge of the state of the immune system in animals with encephalopathy needs broadening. There are remarkable gaps in our knowledge of the histopathology of these diseases, particularly the nature of the characteristic vacuoles. Much further work is needed on the biochemical changes in the brain and the serum, particularly of the latter as it could lead to an additional means of recognizing clinical cases without waiting for the animal to die with subsequent examination of the brain for characteristic lesions and the presence of protease-K-resistant PrP.Abbreviations AI artificial insemination - BSE bovine spongiform encephalopathy - CJD Creutzfeldt-Jakob disease - ET embryo transfer - GSSD Gerstmann-Sträussler-Scheinker disease - HDV hepatitis delta virus - MCF mink cell focus - PK proteinase K - PrP prion protein - PrPSc scrapie prion protein - PrP-C the proteinase-K sensitive homologue in normal brain - SAF scrapie-associated fibrils - TME transmissible mink encephalopathy     

Art, science and mathematics: new approaches to animal health problems in the agricultural industry

This article is about change; particularly the prospect for change in veterinary research during the last decade and a half of the 20th century. The title encapsulates the idea that veterinary medicine, if it is to be effective, periodically has to change its approach to solving animal health problems; that over the last century we have witnessed one major change, that from veterinary medicine as an art to veterinary medicine as a science, and that we are probably on the brink of another change, moving from a scientific or more correctly an experimental approach to a mathematical or observational approach.     

Time‐related changes in post‐operative equine morbidity: A single‐centre study

Our objective was to test the hypothesis that the prevalence and type of post‐operative equine morbidity at a single centre does not change over time with a retrospective and prospective observational study. The post‐operative case records of 92 (of 96) horses undergoing nonabdominal procedures, and surviving to discharge, were compared with previous data from the same centre. Predefined morbidities were recorded from horses undergoing surgery between August 2013 and July 2014. This was compared with data collected from the same institute from April 2004 to June 2005 and published in a previous study. The overall prevalence of morbidities increased from 13.4% to 25%. The prevalence of post‐anaesthetic colic, thrombophlebitis, pyrexia, lameness, neuropathy and myopathy increased while the proportion of incidence of diarrhoea, respiratory distress and wounds sustained in recovery decreased. There was a statistically significant association (P = 0.045) between the duration of surgery and the prevalence of post‐anaesthetic colic. Geldings were less likely (odds ratio 0.12, 95% confidence interval 0.02–0.84) to develop swelling at the catheter site and the likelihood of thrombophlebitis increased by 1.20 (95% confidence interval 1.01–1.41) for every year of life. Tracking morbidities and changes in their prevalence may elucidate their possible causation and allow prophylactic measures to be taken.     

Use of group-randomized trials in pet population research

Communities invest considerable resources to address the animal welfare and public health concerns resulting from unwanted pet animals. Traditionally, research in this area has enumerated the pet-owning population, described pet population dynamics in individual communities, and estimated national euthanasia figures. Recent research has investigated the human–animal bond and explored the community implications of managed feral cat colonies. These reports have utilized traditional epidemiologic study designs to generate observational data to describe populations and measure associations. However, rigorous scientific evaluations of potential interventions at the group level have been lacking. Group-randomized trials have been used extensively in public health research to evaluate interventions that change a population's behavior, not just the behavior of selected individuals. We briefly describe the strengths and limitations of group-randomized trials as they are used to evaluate interventions that promote social and behavioral changes in the human public health field. We extend these examples to suggest the appropriate application of group-randomized trials for pet population dynamics research.     

INVITED REVIEW: STUDY DESIGN CONSIDERATIONS FOR CLINICAL RESEARCH IN VETERINARY RADIOLOGY AND RADIATION ONCOLOGY

High quality clinical research is essential for advancing knowledge in the areas of veterinary radiology and radiation oncology. Types of clinical research studies may include experimental studies, method‐comparison studies, and patient‐based studies. Experimental studies explore issues relative to pathophysiology, patient safety, and treatment efficacy. Method‐comparison studies evaluate agreement between techniques or between observers. Patient‐based studies investigate naturally acquired disease and focus on questions asked in clinical practice that relate to individuals or populations (e.g., risk, accuracy, or prognosis). Careful preplanning and study design are essential in order to achieve valid results. A key point to planning studies is ensuring that the design is tailored to the study objectives. Good design includes a comprehensive literature review, asking suitable questions, selecting the proper sample population, collecting the appropriate data, performing the correct statistical analyses, and drawing conclusions supported by the available evidence. Most study designs are classified by whether they are experimental or observational, longitudinal or cross‐sectional, and prospective or retrospective. Additional features (e.g., controlled, randomized, or blinded) may be described that address bias. Two related challenging aspects of study design are defining an important research question and selecting an appropriate sample population. The sample population should represent the target population as much as possible. Furthermore, when comparing groups, it is important that the groups are as alike to each other as possible except for the variables of interest. Medical images are well suited for clinical research because imaging signs are categorical or numerical variables that might be predictors or outcomes of diseases or treatments.     

马的咽气癖及其防制措施研究进展

在动物的异常行为中以刻板行为最为常见,而咽气癖又是马最常见的口部刻板行为之一。作者就咽气癖在生理方面和心智方面对马体产生的影响、行为基础、诱因的研究进展及常见的防治措施进行综述。     

Mechanisms of Tritrichomonas foetus Pathogenicity in Cats with Insights from Venereal Trichomonosis

Almost 20 years has passed since trichomonosis was first recognized as a potential cause of diarrhea in domestic cats. Despite progress in confirming disease causation, developing means for diagnosis, and identifying approaches to treatment of the infection, we still know very little about how this parasite causes diarrhea. With increasing recognition of resistance of trichomonosis to treatment with 5‐nitroimidazole drugs, new treatment strategies based on an understanding of disease pathogenesis are needed. In this review, lessons learned from the pathogenesis of venereal trichomonosis in people and cattle are applied to clinical observations of trichomonosis in cats in effort to generate insight into areas where further research may be beneficial.     

内蒙古草原不同土壤pH条件下植物生物量和多样性的关系:样带调查和控制实验的比较研究

生物量与多样性的关系一直是生态学研究的热点问题,已有研究显示二者的关系受环境因子的影响,但是关于土壤pH变化对草原植物群落生物量和多样性的影响及其在样带空间调查实验与定点控制实验之间差异的研究还无报道。采用样带调查实验和控制实验相结合的方法,研究了在自然条件下内蒙古草原样带上植物群落生物量和多样性的关系变化及其与土壤pH的关系,同时通过外源添加硫酸或氢氧化钠溶液,研究人为改变土壤pH后草原植物群落生物量和多样性的关系变化,并比较样带调查实验和控制实验两种方法所得结果的差异及机制。研究结果表明:1)在样带空间梯度上,土壤pH变化主要受土壤类型、植被类型及干旱指数的影响。沿天然的pH梯度,地上生物量与土壤pH间呈现为显著的U型曲线关系,物种丰富度与土壤pH也呈显著的U型曲线关系,生物量与多样性二者之间为显著正相关关系;2)在定位的酸碱控制实验中,地上生物量与土壤pH间呈显著的上凸单峰曲线关系,物种丰富度与土壤pH之间也呈显著的单峰曲线关系,生物量与多样性的关系因植被类型而异:在荒漠草原二者为正相关,而在典型草原二者无显著相关性。可以看出,草原生物量和多样性与土壤pH密切相关,并且在样带上和控制实验中呈现出相反的结果,多样性和生物量的关系也不完全相同。两种研究方法出现差异的原因是样带观察反映的是生态系统长期适应的结果,而控制实验结果反映的是生态系统对环境变化的短期响应,这种时空尺度的差异造成了两种研究方法所得结果的不同。     

Equine stereotypic behaviors: Causation,occurrence, and prevention

There are strong suggestions that equine stereotypies are connected to poor welfare and a suboptimal management and/or stabling environment. Different forms of equine stereotypic behaviors have been described. Crib biting, weaving, and box walking are considered the most prevalent. Several studies have been conducted to establish links between the underlying causes and potential function of such behaviors. Both experimental and epidemiological studies have indicated management factors specifically feeding practices, housing conditions, and weaning method as crucial in the development of stereotypies in stabled horses. Some neurological studies on equine stereotypy demonstrated some forms of central nervous system dysfunction as being associated with the performance of stereotypic behaviors. Different researchers hypothesized that the functional significance of stereotypies is that they reduce stress in captive environments and should thus be considered as a coping mechanism. In contrast, the owner's perspective is often that a stereotypic horse has a “stable vice” that needs to be stopped, and different kinds of methods have been developed to control or regulate stereotypic behaviors. However, if the stress-reducing hypothesis is correct, controlling stereotypic behaviors particularly by physical and surgical approaches without addressing the underlying causes is of great concern to the horse's welfare. Although there is ongoing uncertainty about the exact function, the growing knowledge about causation should be applied: under all circumstances prevention is better than cure.     

禽流感群特异性间接原位RT-PCR检测方法

从GenBank下载禽流感病毒(Auian in fluenza virus,AIV)NP基因序列,通过比对选取NP基因中较为保守的片段,设计1对引物,通过RT-PCR方法扩增270 bp的目的片段,经测序确认目的片段序列正确后,用地高辛标记扩增产物制备探针.在BSL-3实验室,用AIV人工感染鸡胚成纤维细胞和SPF鸡后,制作细胞涂片和组织石蜡切片,然后在经前处理后的细胞涂片和石蜡切片上进行原位RT-PCR,再与地高辛标记的探针进行原位杂交,对细胞和组织中的AIV进行检测和定位.研究结果表明,本方法能检测出约1μg/L质粒的DNA,并能特异性地在细胞涂片和石蜡组织切片中检测和定位AIV,且成纤维细胞感染病毒8 h后即可检测到阳性信号,具有良好的特异性和较高的敏感性,为动物组织中AIV的检测定位和致病机理研究提供了敏感、特异和更为直观的方法.     

Metabolic encephalopathies in foals – pay attention to the serum biochemistry panel!

Careful assessment of the biochemistry panel and familiarity with normal biochemistry values for neonatal foals is imperative in the workup of any critically ill neonate, particularly those with neurological signs. The importance of rapidity of change compared to the absolute value of the biochemical abnormality must be emphasised. Serial biochemical panels ideally assist in assessing rapidity of change. Many foals can have severe biochemical derangements in the absence of seizures. Identifying values that are significantly out of range should spur immediate therapy to correct them and potentially additional diagnostic testing to determine the cause of the abnormalities. A temporal relationship between correction of biochemical abnormalities and resolution of seizures and encephalopathic signs supports causation.