As spring arrives and fresh grass starts to grow, many horse owners begin to worry about weight gain, especially in horses and ponies that tend to put on weight easily. Extra weight can quickly lead to obesity, which is an increasing problem in the UK horse population. Often described as a “silent torturer,” obesity is usually the result of overfeeding and lack of exercise. It’s more than just a weight issue, obesity poses serious health risks. It can cause organ damage, contribute to osteoarthritis, and is strongly linked to conditions like Equine Metabolic Syndrome (EMS), insulin dysregulation, and hyperinsulinaemia – all of which significantly increase the risk of laminitis.

Interestingly though, current research is beginning to show strong links between obesity and the hindgut microbiome. Lisa Elliott, MSc of Equine Nutrition Solutions explores these connections and shares her expert advice to help combat equine obesity through the right dietary management and nutrition.

Equine Obesity and EMS

Equine Metabolic Syndrome (EMS) affects how a horse’s body regulates hormones and metabolism, and it’s especially common in ponies. It shares some similarities with type 2 diabetes in humans. While not every overweight or obese horse or pony will develop EMS, there’s a strong link between the condition and excess weight – obesity is often a major factor in those diagnosed with EMS. Common signs of EMS include the development of fat pads in specific areas of the body (known as regional adiposity), difficulty regulating insulin levels (called insulin dysregulation), and a higher risk of developing laminitis, which is a serious health concern.

The impact of the Hindgut Microbiome

The hindgut microbiome—made up of the bacteria in your horse’s digestive system—is essential for breaking down fibre and plays a big role in your horse’s overall health and well-being. While how you manage your horse can certainly affect their weight, the microbiome also influences how effectively they break down food and use energy, which can impact their body condition.

In humans, low levels of gut microbes have been linked to higher insulin resistance and more fat in the bloodstream. Similarly, research in horses (Elzinga et al. 2016; Biddle et al. 2018; Morrison et al. 2018; Morrison et al. 2020) has shown that obese horses have different types and levels of bacteria in their hindgut compared to leaner ones.

One study (Morrison et al. 2020) found that obese horses and ponies had more of a certain type of bacteria that’s especially good at breaking down plant material and releasing energy. This means they might be getting more energy from their food than leaner horses, which could make it harder for them to lose weight. These bacteria have been linked to obesity, although it’s still not clear whether they thrive because of diet, genetics, or both.

Interestingly, research has also found that obese horses and those that lost weight more slowly had a greater variety of bacteria in their hindgut. This higher diversity might be connected to the presence of more bacteria types that are associated with weight gain.

Managing obesity through focused nutrition

Understanding the links between obesity and the hindgut microbiome provide the foundations for preventing and combatting it through focused nutrition, alongside general weight loss management tips and advice.

• Manage Pasture

If you have your own land, a useful way to potentially prevent and combat obesity is to consider the grass types and growth stage of your grazing.  Providing a range of mixed species grasses, can be beneficial as many species can be much lower in sugar, higher in fibre and lower in overall calories than the traditional ryegrass-based pastures in the UK.  Grazing, which is lower in sugar, higher in fibre and lower in overall calories may not only help prevent the development of obesity but may also help reduce the abundance of hindgut microbes linked to obesity, whilst encouraging the growth of microbes less likely to promote it. 

Similarly, letting your horse graze consistently on longer grasses that have gone to seed and are therefore, much higher in fibre and lower in sugar and calories can have the same effects.  However, the amount your horse consumes is key when managing weight loss. A paddock filled with tall, mixed grasses and wildflowers can be ideal but there will ultimately be more grass on offer. Whilst longer grass is lower in calories per average kilo compared to shorter grass if your horse is eating more of it, they won’t lose weight. The ideal solution is to strip graze a taller, mixed grass paddock for really good doers or those who are significantly overweight.

• Improving Microbial Diversity

Encouraging a wide variety of grasses and wildflowers in your grazing areas can help build biodiversity, which in turn supports a healthier and more balanced hindgut microbiome. A diverse diet helps promote a wide range of beneficial microbes, which may reduce the dominance of certain bacteria linked to obesity.

If you don’t have access to mixed-species grazing or your own land, you can still boost biodiversity in simple ways. Taking your horse for a short walk, just 10 minutes a day, along quiet verges and hedgerows allows them to browse naturally. This not only adds variety to their fibre intake, improving digestive health, but also encourages a richer microbial mix in the hindgut. Plus, the walk itself offers valuable exercise.

Another easy option is to make a “hedgerow hay net” by mixing small handfuls of different safe plants with your horse’s regular hay. This is a great way to mimic natural browsing and support a healthy, diverse microbiome.

• Support Good Microbes

Just as certain hindgut microbes are positively correlated with obesity, certain hindgut microbes are positively correlated with a healthy hindgut and leaner horses (Elzinger et al. 2016; Biddle et al. 2018). The entire Coligone range, including balancers, powder and Liquid provide key pro and prebiotics – scFOS, MOS and Yeasacc, which work together to feed, stimulate and promote a healthy population of these beneficial hindgut microbes.  Additionally, a healthy, balanced hindgut microbial population will help reduce the chance of digestive disturbances, whilst potentially helping your horse to maintain a healthy weight.

• Implement a Suitable Diet and Exercise Regime

Creating a ‘calorie deficit’ or in other words more calories going out than in, is key for effective weight loss and can be achieved through a combination of diet and exercise. If your horse is overweight, a suitable calorie reduction diet that doesn’t compromise on fibre intake or essential vitamins and minerals is ideal. Coligone Balancer and Coligone Treats can be fed in smaller amounts, providing essential vitamins, minerals, and protein to support a low calorie, forage-based diet for essential weight loss.

It goes without saying that ensuring your horse has plenty of exercise is one of the most important things you can do to maintain them at a healthy weight.  For an obese horse, however, exercise should be started very gradually and built up to the chosen level once the horse drops weight and becomes fitter.

• Feed for Work Done not What is Anticipated

Feeding unnecessary energy will result in weight gain, so always ensure you feed for the type of work the horse is doing now and not for what may or may not be done in the future. Assessing the level of work your horse is doing correctly and feeding appropriately, is also important, as work levels are commonly overestimated which leads to overfeeding and excess weight.  

Research (Richardson and Murray, 2016) has shown that high fibre diets can easily support the demands of working horses, including those in harder work. If your horse is in regular work, supporting this with a high fibre, easily digestible feed like Coligone Fibre Cubes or Coligone Fibre Bio, will help provide fibre to support work but supply less calories than cereal based feeds.  Coligone LamiGONE cubes are an essential part of a restricted, monitored diet.

• Avoid Over-Rugging

Rugging an already overweight horse will encourage them to hold on to fat reserves rather than burning them to keep warm.  Horses are supposed to use their fat reserves to keep warm in winter, minimising rugs, or turning the horse out without one during the colder months helps them to go towards spring in a much leaner, healthier body condition, reducing the chance of excessive weight gain and obesity. Clipping a woollier coated horse will also assist their weight loss.

• Monitor Weight and Condition Regularly

Using a weight tape and body condition scoring regularly – at least once a month, can help pick up subtle changes in condition and weight loss or gains. In this way, the diet can then be adjusted accordingly to ensure the right amount of condition for optimum health.

If you have any questions about creating the best diet for your horse and keeping your horse healthy through the right nutrition, please get in touch – sales@hbradshaws.co.uk