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.     

A Farrier Making Every Contact Count: A Microlevel Analysis of Farrier-Client Interaction for Partnership Working in Managing a Horse With Laminitis

There is an evidence base in human and small animal veterinary health care contexts which understands how practitioners engage in partnership working with patients and owners to support adherence to treatment/care plans. However, as yet, it is believed there is no similar evidence base for how practitioners in equine health care contexts work with equine owners. It is argued that this is essential for understanding complex equine practitioner-owner interaction involving the prevention and management of laminitis. The aim of this study was to explore farrier-client interaction where risk management for an equine recovering from laminitis was being undertaken. A case report method involved a microlevel analysis of a farrier-client consultation. The consultation was video-recorded and analyzed using a conversation analysis approach to identify the linguistic and paralinguistic features of the interaction. These were compared with conversation analyses in other health care contexts to identify the actions being accomplished within the consultation. The analysis identified a number of joint actions, including managing epistemic stance (or knowledge rights) and deploying the animal’s presence to navigate problem sequences which supported progression of the consultation through a three-stage model involving “team-”, “option-”, and “decision-” talk, known to be associated with partnership working in human health care contexts. The study highlights the importance of developing an empirical evidence base in equine practice for how practitioners engage with owners based on a microlevel analysis of real-world interactions. It is argued this evidence base is necessary in supporting effective practitioner training in partnership working with clients to promote their adherence to treatment/care plans.     

Stereotypies and behavioural medicine: confusions in current thinking

Stereotypies are defined as being repetitive, unvarying behaviours that appear to have no goal or function. This group of behaviours presents itself commonly in clinical behavioural practice. In recent companion animal behaviour literature the nomenclature has been changed to obsessive-compulsive disorder without considering the confusion this may create. Theories about the role endorphins play as a cause of stereotypies and an assumption about stereotypies playing a 'coping' role have been presented as scientific fact with little evidence supporting them. A failure to consider changes associated with stereotypy maturation and a reliance on anecdotal treatment success has lead to confusion regarding certain aspects of the development, diagnosis and treatment of these conditions. In this paper I present the idea that much of our confusion surrounding stereotypies is created by attempts to oversimplify a complex phenomenon.     

Fancy: An Equine Nutrition and Management Model

Nutrition and management modeling has been expanding rapidly in the last 30 years. Nutrition and physiology models in ruminants have used different modeling techniques ranging from simple empirical-based to mechanistic and dynamic models. The level of complexity is driven by available data and modeler objective. The two primary objectives are to serve as a research tool to help guide future research versus field-applied models. Field-applied models combine empirical and mechanistic techniques, allowing nutritionists and consultants to evaluate and predict animal performance by using inputs that can be collected on-farm and by using standard laboratory methodology. More complex dynamic/mechanistic models have been historically used to guide research. These models have tended to focus on enhancing the biochemical understanding associated with lactating cows. Regardless of methodology, modeling has improved the nutrition and feeding practices of all species in which it has been used. However, limited modeling has occurred regarding the equine. The objectives of this article are to introduce the basis for an equine model (Fancy) and outline how modeling can be used to enhance knowledge by guiding research projects. During the development of Fancy, inconsistencies related to requirement predictions were discovered. Most inconsistencies were related to data limitations; however, this illustrates where modeling can offer significant rewards. The development of a model can assist in defining these inconsistencies and data limitations. Research resources can then be better allocated to address these issues, resulting in expanding the knowledge base of the system being modeled.     

Immunological characterization of the equine airway epithelium and of a primary equine airway epithelial cell culture model

Our understanding of innate immunity within the equine respiratory tract is limited despite growing evidence for its key role in both the immediate defense and the shaping of downstream adaptive immune responses to respiratory disease. As the first interface to undergo pathogen invasion, the respiratory epithelium is a key player in these early events and our goal was to examine the innate immune characteristics of equine respiratory epithelia and compare them to an in vitro equine respiratory epithelial cell model cultured at the air-fluid interface (AFI). Respiratory epithelial tissues, isolated epithelial cells, and four-week old cultured differentiated airway epithelial cells collected from five locations of the equine respiratory tract were examined for the expression of toll-like receptors (TLRs) and host defense peptides (HDPs) using conventional polymerase chain reaction (PCR). Cultured, differentiated, respiratory epithelial cells and freshly isolated respiratory epithelial cells were also examined for the expression of TLR3, TLR9 and major histocompatibility complex (MHC) class I and class II using fluorescence-activated cell sorting (FACS) analysis. In addition, cytokine and chemokine profiles from respiratory epithelial tissues, freshly isolated respiratory epithelial cells, and cultured, differentiated, epithelial cells from the upper respiratory tract were examined using real-time PCR. We found that respiratory epithelial tissues and isolated epithelial cells expressed TLRs 1-4 and 6-10 as well as HDPs, MxA, 2'5' OAS, β-defensin-1, and lactoferrin. In contrast, epithelial cells cultured at the AFI expressed TLRs 1-4 and 6 and 7 as well as MxA, 2'5' OAS, β-defensin-1, but had lost expression of TLRs 8-10 and lactoferrin. In addition, MHC-I and MHC-II surface expression decreased in epithelial cells cultured at the AFI compared to isolated epithelial cells whereas TLR3 and TLR9 were expressed at similar levels. Lastly, we found that equine respiratory epithelial cells express an array of pro-inflammatory, antiviral and regulatory cytokines and that after four weeks of in vitro growth conditions, equine respiratory epithelial cells cultured at the AFI retained expression of GM-CSF, IL-10, IL-8, TGF-β, TNF-α, and IL-6. In summary, we describe the development of an in vitro equine respiratory epithelial cell culture model that is morphologically similar to the equine airway epithelium and retains several key immunological properties. In the future this model will be a used to study equine respiratory viral pathogenesis and cell-to-cell interactions.     

Maintenance of equine anaesthesia over the last 50 years: Controlled inhalation of volatile anaesthetics and pulmonary ventilation

In the first edition of this journal, Barbara Weaver wrote a review titled ‘Equine Anaesthesia’, stating that, at that time, it was quickly becoming accepted practice that many horses were being anaesthetised ‘by essentially similar procedures, i.e. premedication, induction and then maintenance by controlled inhalation’. To celebrate the 50th anniversary of the first edition of this journal, this review covers the development of understanding and practice of inhalational anaesthesia and controlled ventilation in horses over the last 50 years. We review how the perceived benefits of halothane led to its widespread use, but subsequently better understanding of halothane's effects led to changes in equine anaesthetic practice and the utilisation of different inhalation agents (e.g. isoflurane and sevoflurane). We discuss how more recently, better understanding of the effects of the ‘newer’ inhalation agents’ effects has led to yet more changes in equine anaesthetic practice, and while, further new inhalation agents are unlikely to appear in the near future, further enhancements to anaesthetic practice may still lead to improved outcomes. We review advances in our understanding of the anatomy and pathophysiology of the equine lung as well of the effects of anaesthesia on lung function and how these predispose to some of the common problems of gas exchange and ventilation during anaesthesia. We identify the aims of optimal mechanical ventilation for anaesthetic management and whether the various methods of ventilatory support during equine anaesthesia achieve them. We also highlight that further developments in equipment and optimal ventilator modes are likely in the near future.     

The Influence of Stable Management and Feeding Practices on the Abnormal Behaviors Among Stabled Horses in Malaysia

The present study aimed to provide preliminary data on the prevalence of oral stereotypic, locomotory stereotypic, and redirected behaviors as well as their associations with stable management and feeding practices. In this cross-sectional study, a total of 207 working horses used for leisure riding, equestrian sport, polo, endurance, and patrolling were selected from seven equine facilities. Data on the stable management and feeding practices were obtained through the stable records, interviews, and on-site monitoring visits, whereas the prevalence of abnormal behaviors in the studied population was determined using the instantaneous scan sampling method. Most horses in the present study worked for more than 8 hours per week (n = 93). In addition, more horses were fed three times per day (n = 65) with different amounts of hay, concentrate, and chaff. Among the study population, oral stereotypic behaviors had the highest prevalence (n = 281; 54%), followed by redirected behavior (n = 181; 34%), and locomotory stereotypic behaviors had the lowest prevalence (n = 63; 12%). The oral stereotypic behavior was found to be significantly influenced (P < .05) by the working hours, amount of hay, and amount of concentrate. Both locomotory stereotypic and redirected behaviors were found to be influenced (P < .05) by the number of feedings per day and the amount of hay. In summary, the present study has proven that the stable management and feeding practices could influence the prevalence of different abnormal behaviors in the majority of working horses, with oral stereotypy being the most common abnormal behavior in this country.     

Stereolithographic biomodeling of equine ovary based on 3D serial digitizing device

The 3D internal structure microscopy (3D-ISM) was applied to the equine ovary, which possesses peculiar structural characteristics. Stereolithography was applied to make a life-sized model by means of data obtained from 3D-ISM. Images from serially sliced surfaces contributed to a successful 3D reconstruction of the equine ovary. Photopolymerized resin models of equine ovaries produced by stereolithography can clearly show the internal structure and spatial localizations in the ovary. The understanding of the spatial relationship between the ovulation fossa and follicles and/or corpora lutea in the equine ovary was a great benefit. The peculiar structure of the equine ovary could be thoroughly observed and understood through this model.     

Deciphering the Role of Bronchial Hyper-Responsiveness in Equine Pasture Asthma

Bronchial hyper-responsiveness (BHR) describes a lung abnormality in which airways are easily triggered to constrict in response to normally harmless inhaled stimuli, and is a key element of human asthma pathophysiology. BHR contributes to equine respiratory diseases including inflammatory airway disease and recurrent airway obstruction. Collectively these diseases account for over 80% of poor performance in equine athletes, and at least 10% of veterinary admissions. BHR is also a contributing factor in ‘exercise induced pulmonary hemorrhage’. Increased sensitivity to airway constriction that characterizes BHR is a documented sequel to viral respiratory infections in several species, including horses and humans. Five respiratory viruses known to circulate extensively in equine populations place the horse at risk for BHR. Despite adverse effects of BHR on equine health, there remains a gap in our fundamental understanding of how gene products coordinate in the lung to cause BHR. Leveraging the equine genome sequence, we employ systems biology including proteomics and RNA sequencing to model the complex biology of BHR in the lungs of horses with pasture asthma. Using a self controlled experimental design, gene products that segregate with seasonal asthma exacerbation in diseased horses are being identified and their relevant physiology identified to address the need for better recognition and management of BHR in equine disease.     

Eosinophils of the horse: Part I: Development,distribution, structure and biochemical mediators

Eosinophils are becoming the target of increasing research interest as recent studies suggest that their role in immune homoeostasis and the immune response to disease is far more complex than previously understood. Historically, the horse eosinophil has been used to study basic eosinophil biology because of the considerable volume of blood required to obtain enough viable cells for reliable, repeatable experiments. This resulted in a large but disseminated body of literature pertaining to the structure and function of the horse eosinophil. More recently, equine clinicians have produced case reports and clinical studies in an effort to define the role of the eosinophil in diseases of the horse. A thorough review of the equine eosinophil incorporating both bench research and clinical reports does not exist. The objective of this two-part review is to fill this need by integrating the basic science and clinical research into a comprehensive body of work on what is known specifically about the horse eosinophil, and its role in equine health and disease. Part I summarises the development and tissue distribution of eosinophils in the normal horse, and presents what is known about the cell structure, migration and biochemical mediators of the horse eosinophil. Part II reviews the role of the eosinophil in diseases of the horse, and concludes with a summary of knowledge gaps and open research questions to benefit both those who wish to use the equine eosinophil as a model for basic science research, and those whose primary interest lies with diseases of horse.     

Multivariable prediction model for the need for surgery in horses with colic.

A survey of 1,965 equine colic cases was conducted from August 1985 to July 1986 at 10 equine referral centers located throughout the United States. The purpose of this study was to develop and validate a multivariable model for the need for surgery. Two-thirds of the cases were randomly selected for model development (1,336), whereas the remaining cases (629) were used only for subsequent validation of the model. If a lesion requiring surgical correction was found at either surgery or necropsy, the case for the horse was classified as surgical, otherwise the case was classified as medical. Only variables that were significant (P less than 0.05) in an initial bivariable screening procedure were considered in the model development. Because of the large number of missing values in the data set, only variables for which there were less than 400 missing values were considered in the multivariable analysis. A multivariable logistic regression model was constructed by use of a stepwise algorithm. The model used 640 cases and included variables: rectal findings, signs of abdominal pain, peripheral pulse strength, and abdominal sounds. The likelihood ratio for surgery was calculated for each horse in the validation data set, using the logistic regression equation. Using Bayes theorem, the posttest probability was calculated, using the likelihood ratio as the test odds and the prevalence of surgery cases (at each institution) as an estimate of the pretest odds. A Hosmer-Lemeshow goodness-of-fit chi 2 statistic indicated that the model fit the validation data set poorly, as demonstrated by the large chi 2 value of 26.7 (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Molecular detection of Coxiella burnetii and Neospora caninum in equine aborted foetuses and neonates

Abortion, stillbirth and neonatal death are major causes of equine mortality and cause severe economic loss to the equine industry. The present study was based on a complete necropsy protocol associated with classical microbiological examinations and molecular biology on 407 cases of abortion, stillbirths and neonate death. Based on this retrospective survey, "less common" abortive infectious agents were characterised by molecular tools in nine independent cases of abortion or neonate mortality. Among others, Chlamydophila abortus (1 case), Coxiella burnetii (6 cases) and Neospora caninum (3 cases) were detected by real-time PCR; one of these samples being co-infected by N. caninum and C. burnetii. DNA detection of this latter bacterium is reported here for the first time in equine abortion samples. C. burnetii should, along with other common pathogens, probably be taken into account in equine abortion.     

Equine Farm Operators: An Underserved Target Audience for Conservation Practice Outreach?

Equine farms account for an increasing proportion of land use in many areas of the United States. Despite this, equine farm operators have often been neglected by researchers and resource professionals when land management decisions are concerned and little is understood of this community's awareness and use of conservation practices. This study assessed the prevalence of conservation messages in equine-related trade magazines using content analysis. In-depth interviews were also conducted with equine farm operators to assess their understanding and use of conservation practices. Conservation-related material in equine media is relatively rare when compared with traditional livestock magazines. Equine and stable owners are generally motivated to protect on-farm resources but are not very aware of the off-farm effects of their operations. Several common livestock conservation practices are being used by many facilities, but the motivation for their use is not based on environmental concern, and operators are generally unaware of the environmental benefits of these practices. More outreach and education directed at equine farm operators is needed.     

Equus caballus papillomavirus‐2 (EcPV‐2): An infectious cause for equine genital cancer?

Reasons for performing study: The aetiology of genital squamous cell carcinoma (SCC) in horses remains unknown, but the similarity to the disease in man, for which papillomavirus infection has been shown to be a causal factor, requires to be investigated in horses. Hypothesis: One or more novel papillomaviruses cause equine genital SCC and its associated premalignant lesions. Methods: DNA was extracted from samples of equine genital SCC and performed rolling circle amplification, in order to identify closed circular DNA viral genomes within the samples. The amplified DNA was subcloned and sequenced and the DNA sequence compared to that of other papillomavirus genomes. Using PCR primers developed from these genomic DNA sequences, studies were then carried out in order to identify the frequency at which the viral DNA could be identified in equine genital cancer samples from horses in both the UK, Australia and Austria. Finally, in situ hybridisation using specific probes developed from this DNA sequence were used to confirm the presence of the viral RNA sequences in the neoplastic cells in these lesions. Results: The full length genome of a novel papillomavirus species was characterised from the equine genital SCC tissue and termed Equus caballus papillomavirus‐2 (EcPV‐2). Viral DNA and RNA was identified in the genital tumour samples, but not in the adjacent histologically normal tissue. EcPV‐2 DNA could not be identified in equine ocular or nasal carcinomas or within the scrotal skin or in most smegma samples obtained from tumour‐free horses. Sequencing of amplicons, generated from the archived equine genital tumours, identified variations within E1 and E6 on DNA and predicted protein level. Conclusions: A novel papillomavirus, EcPV‐2, is likely to play a causal role in the pathogenesis of equine genital epithelial tumours. Potential relevance: Identification of a papillomavirus causal for genital carcinomas in horses may lead to development of a vaccine that could be used to prevent this serious disease in horses. This would be analogous to man, where vaccination against oncogenic papillomavirus species is currently being used to help prevent cervical cancer.     

Equine Nutrition in the United States: A Review of Perceptions and Practices of Horse Owners and Veterinarians

Nutrition plays a critical role in equine health. The horse owner and/or manager has a multitude of equine nutrition sources available to them, with preferences for how, and from whom, this information is delivered. Despite this, poor feeding practices continue to negatively affect the health, wellness, and welfare of equids and have a detrimental impact on the environment. The veterinarian is the primary expected source of equine nutrition information; yet, little is known about their recognition and acceptance of such a role. Doubt has arisen concerning the quality and provision of nutrition education within the veterinary curriculum and subsequent continuing education. Moreover, the value equine nutrition education plays in the veterinarian's practice philosophy, and the resulting provision of such in clinical practice, remains under evaluated. This review examines the present state of equine nutrition and how horses are being fed in practice, in the United States. It considers feeding horses from the horse owner's perspective and the expected role the veterinarian plays in such. Last, it goes on to evaluate this expected role from the veterinarian's perspective, examining how current nutrition education and practices may be falling short and offering recommendations for future research.