A scoping review of the current literature exploring the nature of the horse-human relationship

¹School of Veterinary Medicine and Science, University of Nottingham, College Road, Sutton Bonington, Leicestershire, LE125RD
^*Corresponding Author (Sarah.Freeman@nottingham.ac.uk)

Objective: To perform a scoping review of the current evidence on the horse-human relationship.

Background: The horse-human relationship has a significant impact on how horse owners care for and make decisions for their horse.

Evidentiary value: Identification of consensus and gaps in current evidence.

Methods: A literature search was performed in CAB Abstracts and Medline using search terms relating to the nature of the horse-human relationship in horses used for pleasure riding. Publications were reviewed against inclusion and exclusion criteria. Original qualitative or observational research studies relating to the relationship between a horse and owner were analysed. Data were extracted on study method and population characteristics.

Results: There were 4,481 studies identified; 27 studies were included in the final data extraction. The studies covered 11 different areas, the most frequent were effect of humans on equine behaviour (5/27), equine training methods and behaviour (4/27) and horses within sport and leisure (4/27). A range of methodologies were used, with the most frequent being thematic analysis (6/27 studies), use of an instrument, tool or scale (3/27) and behavioural scoring (4/27). The majority of studies considered the human’s perspective (20/27), six considered the horse perspective and one considered both the horse and human perspective. No studies investigated the same or similar aims or objectives.

Conclusion: The current evidence on the horse-human relationship is diverse and heterogenous, which limits the strength of evidence for any particular area.

Application: Future research should focus on developing reliable and repeatable tools to assess owner motivations and horse-human relationship, to develop a body of evidence.

From its first domestication over 6,000 years ago, the horse – Equus ferus caballus – has evolved from its primary role as working animal into additional roles as much-loved and reliable companions (Endenburg et al., 1999). The evolution of their use has in turn influenced not only the way we interact with horses today, but also the relationships that are formed between horses and humans (Hausberger et al., 2008). Consequently, it is important to gain an understanding of horse-human relationships in today’s environment, and how these relationships influence decisions made at key stages within a horse’s life.

There are currently around 100 million working equids (horses, donkeys and mules) across the world, predominantly located in poorer or developing countries, where they have a major role in rural economies and the lives of the families and communities that depend on them (World Horse Welfare, 2019). In the UK, the role of the horse is, however, very different. A recent survey carried out by The British Equestrian Trade Association (2019) found that there are around 847,000 horses, and 374,000 horse-owning households in Britain. It has also been reported that 96% of UK horse owners ride for pleasure and 53% of these have horses whose main role is for leisure riding and hacking, which represents a major change from a utility-based role, to a companion-based role important in sport and leisure (Dashper, 2014).

A review carried out by Hausberger et al. (2008) explored the various areas of the horse-human relationship which included tools to assess horses’ relation to humans, exploration of the bond between a foal and a human, and matching of the horse and rider. This is only a single review and there are no comprehensive peer-reviewed studies of the topic. Performing a scoping review to describe the current research available on the horse-human relationship may be beneficial prior to performing systematic reviews. It would enable us to identify and categorise which aspects of the horse-human relationship have previously been explored, and identify where there are existing bodies of evidence or current gaps in knowledge and research. For this study, the definition of ‘relationship’ described by Hinde (1979) was used: ‘the emerging bond from a series of interactions: partners have, on the basis of the past experiences, and expectations on the other individual's responses’.

A scoping review is similar to a systematic review and follows many of the methodological steps. The review type provides a preliminary evaluation of the size and scope of available literature in order to gauge the nature and extent of research evidence (Grant and Booth, 2009). Arksey and O'Malley (2005) described the motivations as to why a scoping review may be performed which included: to investigate the range, extent and type of research activity; to determine the value of performing a full systematic review; to summarise and distribute findings or to identify gaps in the existing literature.

The aim of this scoping review is to investigate and categorise the current published literature regarding the nature of the horse-human relationship in horses used for pleasure riding.

Protocol and registration

This review has not been registered to an existing protocol. This scoping review was conducted using the methodological framework presented by Arksey and O'Malley (2005) and the results are presented using the PRISMA extension for scoping reviews (Tricco et al., 2018).

This project was reviewed and approved by the Ethics Committee, School of Veterinary Medicine and Science, University of Nottingham.

Eligibility criteria

To be eligible for the review, papers needed to investigate the relationship, bond or interactions between horse and human for horses used for pleasure. Papers were included if they reported on original research studies, and the full text of the paper was available and published in English. The study focused on the literature around pleasure horses, and therefore studies on animal-assisted therapy, working equids, and horses used for agricultural purposes were excluded (Table 1).

Table 1: Inclusion and exclusion criteria used to perform a scoping review of current publications exploring the horse-human relationship.

For the purposes of this study, the following definitions were used for the exclusion criteria:

¹Studies of use of equids for animal-assisted therapy: defined as a study, or person or people having intermittent access to an animal with the aim of improving specific physical, mental or social functioning.

²Studies of working equids in developing countries: defined as studies of working equids in any countries listed by the Development Assistance Committee (DAC) of the Organisation for Economic Co-operation and Development (OECD) eligible for Official Development Assistance, 2017 data (ODA list).

³Studies of equids for agricultural use: defined as equids that provide support to farmers in developing countries for example carrying feed and water for livestock and connecting farmers to cooperatives and markets (Brooke, 2015).

⁴Experimental/quasi-experimental studies: experimental studies defined as studies which compare different treatments, where the researcher controls treatments using a randomised controlled study or control groups. Quasi-experimental studies defined as those that compare different treatments where the treatments are not randomised or are not controlled by the researcher (e.g. comparing responses pre and post-treatment in same patient).

Information sources and search strategy

A literature search was performed on 13.11.17 and updated on 11.04.19 using CAB Abstracts (1910–present) and Medline (1946–present), which have been reported as the two key databases for veterinary literature (Grindlay et al., 2012). The following search terms were used: human, person, people, individual, horse, equine, equid, equus, equi, relationship, bond, interaction. All references were downloaded and managed in Endnote reference manager (Endnote X8.0.1).

Selection of sources of evidence

Any duplicate papers were removed and the titles were reviewed by the primary researcher (H. Clough). Publications were retained if the titles contained terms relating to the horse-human relationship. Any titles that were ambiguous were retained for abstract review. Abstracts were reviewed and retained if they related to studies of factors associated with the horse-human relationship and the search terms described above. Any studies identified during the abstract review that did not have the full text available were excluded. Any abstracts that were ambiguous were retained for full text review. The full text of included publications were then reviewed against inclusion and exclusion criteria (Table 1) by two researchers (H. Clough and S. Freeman) to agree the final included studies (Figure 1).

Data charting process and data items

The included publications were analysed to generate data extraction tables for the methods and population characteristics of each of the publications. Data extracted for study methods were: title; author; study methodology; aims; measures; and key outcomes as self-reported by the authors. Data extracted on study populations were: author and date; location; study participants; population size; and study perspective. The study perspective was established by identifying the study population and objectives.

No additional analysis was conducted. Methodological quality or risk of bias of included studies was not appraised, consistent with guidance on scoping review conduct (Arksey and O’Malley, 2005; Tricco et al., 2018).

Selection of sources of evidence

A total number of 5018 studies were found on the initial database searches. There were 132 papers included after the abstract check, however only 112 of these had the full text available (Figure 1). From these 112 full text publications, 85 studies were excluded from final analysis as they did not meet the final inclusion criteria (Table 1); the excluded studies were 33 reviews (two of which were systematic reviews), 14 studies of animal-assisted therapies, six studies of working equids, 28 experimental or quasi-experimental studies and four studies which did not investigate the horse-human relationship (Figure 1). There were 27 papers which met the final inclusion criteria and were therefore analysed and data presented in extraction tables comparing study, method and population characteristics.

Figure 1: PRISMA flow diagram demonstrating the process used for a scoping review on the current literature exploring the horse-human relationship and how the final 27 included studies were identified.

From: Moher et al., The PRISMA Group (2009).

Characteristics of source of evidence

The data regarding the study methodology for each of the 27 included studies are presented in Table 2. A range of different study methods were used, including questionnaires (n=11), behavioural observational studies (n=7), focus groups (n=1), ethnographic studies (n=5), interviews (n=2) and mixed methods (n=1).

The measures used in the studies included: thematic analysis (n=7); instrument, tool or scale (n=4); behavioural scoring (n=4); mixed measures (n=3); open and closed questions (n=4); interview scoring guide (n=1); Likert/VAS scale (n=1); component analysis of data (n=1); physiological parameters (n=1); and behavioural scoring and physiological parameters (n=1) (Table 2).

The aims of each of the studies were all individual. There were no studies investigating the same or similar aims and objectives, but there were some similarities between studies and the areas in which they explored. These areas included: the effect of humans on equine behaviour and reactions (n=5); equine training methodologies and behaviour (n=4); horses within sport and leisure (n=4); equine welfare (n=3); human attachments and bonds to horses (n=3); horse-human ecologies (n=2); the influence of human-animal relationship on psychological wellbeing (n=2); equine euthanasia (n=2); the importance of personality traits to breeders (n=1); and colic decisions (n=1) (Table 2).

Table 2: Data extraction table for method characteristics of 27 publications that met the final inclusion criteria for a scoping review of literature exploring the horse-human relationship.

Population characteristics

Table 3 presents the population characteristics of these studies. All 27 studies were published within the last 17 years. Fifteen studies were published within the last 5 years (2014–2019), eight studies were published between 2009 and 2013 and four studies were published before 2009. The majority of these studies were carried out in Europe (n=15), with eight of these conducted in the UK. Most studies focused on one perspective rather than the two-way interaction involved in the horse-human relationship; perspective of the human (n=20), perspective of horses (n=6), perspective of both (n=1) (Table 3).

Table 3: Data extraction table of population characteristics from 27 publications that met the final inclusion criteria of a scoping review of literature exploring the horse-human relationship.

The human animal relationship has become an increasingly popular area for scientific research (Hosey and Melfi, 2014; Dashper, 2017). Research in this area has predominantly explored the relationships that humans have with companion animals, and only more recently the relationship that humans have with horses. The exploration of the horse-human relationship through a scoping review identified a diverse and heterogeneous body of published literature. Scoping reviews, unlike systematic reviews, do not strive for evidence synthesis or appraisal of research quality of the studies, but instead pose a transparent and thorough map of research areas identified (Arksey and O'Malley, 2005). Heterogeneity across the 27 publications identified in this scoping review highlights the benefits of performing a scoping review prior to an extensive literature review. Very limited comparisons of aims, objectives and methodologies could be drawn across the publications, but this study provides the framework to define more specific research questions and systematic reviews for future research, by extracting key information and grouping and categorising data. The research areas identified by this review as having the most studies were: equine behaviour and reactions towards humans (5/27); equine training methodologies and behaviour (4/27) and horses within sport and leisure (4/27).

Broad search terms and inclusion criteria were used for this scoping review to gain an understanding of the current scientific research involving the horse-human relationship and what, if any, specific research areas could be identified. This also raised challenges: it led to a large variability in the studies that were identified using the search terms, including literature on working equids and animal-assisted therapies. It was decided after the initial database search and categorisation of research areas that these research areas would be excluded from the final scoping review, allowing the focus to remain on the relationship between humans and horses applicable to the main horse owning population within the UK. It is important however, to appreciate that the relationship humans have with working equids and the use of equids in animal-assisted therapies, are important areas of research within the horse-human relationship. These require further investigation to gain a better understanding of the available research within the areas themselves, independent of this study. The results of the initial searches from the scoping review highlighted the numbers of publications in each area, which will be helpful to inform future systematic reviews.

For this review, 27 studies met the inclusion criteria. Only two databases were used for the literature search; these databases were deemed the most appropriate for veterinary literature (Grindlay et al., 2012) and therefore most suitable for a scoping review. The searches used in this study did not identify some studies which would have met inclusions criteria for example; Chamove et al. (2002) and Maurstad et al. (2013), as the journals were not within the Medline or CAB Abstracts databases. A more detailed systematic review would require inclusion of other databases that may be more inclusive of other social science journals and studies, such as the International Bibliography of the Social Sciences. This scoping review has demonstrated the diversity of the publications in this area and therefore the challenges in defining databases and search strategies for an area that is currently ill defined and multi-disciplinary in nature. A systematic review investigating human-animal relationships, bonds and interactions performed by Hosey and Melfi (2014) identified 116 publications involving companion animals (dogs, cats and equids), of which 22 involved the human-animal relationship. This review did not state how many of these publications involved equids exclusively, however it suggests that 27 publications identified by this current review represents a reasonable body of the current evidence. There were however methodological differences, including the databases searched (Proquest and Google Scholar) and the lack of defined inclusion and exclusion criteria in the study by Hosey and Melfi (2014).

Of the publications reviewed in the current study, only one involved the dyadic relationship of human and horse, with the majority focusing only on one perspective (horse or human). The lack of exploration of the two-way interaction between humans and animals was also identified by Dwyer et al. (2006), subsequently leading to the development of the Monash Dog Owner Relationship Scale (Dwyer et al. 2006). Further research into the two-way relationship between horses and humans may be beneficial to understand how best to match horses with owners or riders, and to prevent incompatibilities that may become detrimental to the horse or human.

A diverse range of publication aims, objectives and methodologies were identified in this review, and there was significant diversity in the research areas and topics. Some major gaps in the research and lack of evidence for a number of areas were identified, and these were used to identify areas which should be considered for future research:

1. Development of a reliable and repeatable tool for categorising horse owners’ motivations and reasons for being involved with horses.
2. Development of a reliable and repeatable system for categorising the different roles and activities that horses are used for.
3. Development of a tool for defining the different types of relationships people form with horses and other equids.
4. Identification of the horse factors and the owner factors that influence the horse-human relationship, and how these interact and affect owner decision making.

It can be concluded that the research surrounding the relationships between horse and human is extremely diverse and heterogeneous, with a paucity of evidence in most areas. From this scoping review of the literature, key areas of current research evidence were identified and defined, but gaps within the research body exploring the nature and factors influencing the horse-human relationship were also documented. The main limitations were around the challenges in identifying suitable publications, and social science databases should be included in future reviews. This review highlights the need for further investigation (systematic reviews) into the main research areas defined by the review, but also the need for new studies to fill significant gaps within the research. Gaining an understanding of the relationships we have with animals is important to help us understand how and why health and welfare may be compromised by inadequate or inappropriate decision making. The horse-human relationship is clearly a key component of this but is lacking a significant evidence-base. Exploration into the relationships that horse owners have with their horses, and the influence this may have on their decisions was identified as an area with little published literature.

The authors declare no conflicts of interest.

Funding: This work was funded by The Horse Trust as part of a MRes studentship for Harriet Clough.

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