Obesity: An Equine Welfare Issue
Obesity in animals is becoming more of a widespread issue, especially in well developed, western countries (Dugdale et al., 2012; Catalano et al., 2016; Morrison et al., 2017). It is well known that it can be a contributing factor in a range of health issues, suggesting that obesity is an indicator of poor welfare in horses. Owers and Chubbock (2013) suggest that it is the most important welfare issue affecting equines in the present day, as they propose that it is becoming standard practice for horses to be overweight. Equine obesity is a widely discussed topic, especially regarding disciplines such as showing, with the “Fit Not Fat” debate (Stanley, 2018) continuing with each new competition season. Whilst most research on obesity appears to reach similar conclusions, there are some questions raised regarding the validity of ideas drawn.
The main conclusion drawn from the majority of the evidence looked at is that obesity causes major issues for horses of all ages, breeds and types, although some are predisposed to suffering from obesity more than others, such as native breeds (Giles et al., 2014). It was widely concluded that obesity/diet is a major cause of laminitis in horses, which if not managed correctly, can prove fatal (Geor, 2008; Geor, 2010; Murray et al., 2015). This could be due to the changes in management of the domesticated horse, compared to those in their natural habitat. In the wild, a horse’s weight will fluctuate with the seasons due to the amount of food available, meaning they tend to be lighter coming out of winter, allowing for the rise in sugar in spring grass, therefore being less likely to trigger laminitis. However, some domestic horses may be kept in the same condition all year round, which could mean that they are at higher risk of developing laminitis, if their weight is more than recommended. Giles et al. (2014) acknowledged the need to consider seasonal weight loss/gain when assessing condition, particularly in relation to management.
Many other health issues have been linked to obesity, such as respiratory problems (Owers and Chubbock, 2013), Equine Metabolic Syndrome (Murray et al., 2015) and osteoarthritis (Schlueter and Orth, 2004) who suggested that when linked with poor conformation, obesity could have a negative impact on weight bearing joints.
Hoffman, et al. (2003) propose that insulin resistance could be linked to obesity, which could lead to several secondary issues such as exertional rhabdomyolysis (Valentine et al., 2001) and colic (Hudson et al., 2001). Hoffman et al. (2003), found that insulin sensitivity was 80% lower in obese horses.
Obesity has also been linked to behavioural issues, as well as physiological. Buckley et al. (2013) found that obesity had a negative effect on behaviour. They concluded that being overweight had an impact on the behaviour/performance of Pony Club ponies. However, there could also have been other contributing factors, which may not have been directly linked with weight.
A key issue discovered by Owers and Chubbock (2013) is that people are more likely to be able to see and be concerned by a horse that is underweight than overweight. A common way to estimate a horse’s weight is to use a Body Condition Score (BCS) system (Dugdale et al., 2012) in which the horse’s condition is assessed on a scale of one to nine, one being poor and nine being extremely fat (Baileys Horse Feeds, 2018). BCS is a widely used method, not only in everyday practice, but also in studies providing evidence. However, the main issue with using BCS is that it is subjective (Morrison et al., 2017). Mottet et al. (2009) suggest that non-professionals subjectivity could cause issues, as people may not recognise when their horse is overweight. As Horseman et al. (2016) propose, feeding practices can be a cause of poor welfare. As well as causing obesity, colic could also become an issue. This is supported by Murray et al. (2015), who carried out a survey on horse owners, and found a slight lack of knowledge regarding feeding, especially with people relying on tradition. They concluded that further education is needed, although they did have responses which showed good knowledge, as well as a willingness to be educated. Although their sample was large, it consisted of mainly females, and although this may be due to more female caregivers involved with horses, it may not be representative of the population due to a lack of male response. They concluded that good knowledge of nutrition is imperative for good welfare.
Despite a large amount of research on obesity as an indicator of poor welfare in horses, some is becoming out of date so more current research may be needed, although there is some up to date research available.
The general understanding among those in the equine industry, from veterinary professionals to everyday caregivers, is that obesity is a good indicator of poor welfare, due to the issues it can cause, although some research suggests that further education may be needed to help tackle the problem.
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