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Equine Metabolic Syndrome (EMS) in horses

If a horse has too much body fat, this can increase the risk of developing so-called diseases of affluence. These types of diseases are also known as diseases of civilisation because they only occur in horses in human care. Being excessively overweight puts a strain on the horse’s entire organism. Equine metabolic syndrome, or EMS for short, is being diagnosed more and more frequently in horses as a result of severe obesity. EMS is a clinical syndrome that significantly disrupts the horse’s metabolism and is one of today’s diseases of affluence.

Why do horses today suffer more frequently from welfare diseases?

Originally, horses were steppe animals that lived in herds and spent their daily lives searching for food. The environment often offered only meagre, fibre-rich fodder. Horses rarely found high-energy foods such as fresh fruit or grains in the wild. They therefore had to travel long distances every day to find enough food.

Domestication changed their lifestyle; initially used for work, horses required more energy, which was met with energy-rich grains. Nowadays, most horses serve as leisure companions and no longer perform heavy labor, leading to less exercise and more weight gain due to rich pastures and concentrated feed. This quickly throws the horses’ energy balance out of kilter – they put on weight and often suffer from obesity. Obesity is already one of the diseases of affluence and can trigger the development of other diseases of affluence, such as EMS.

EMS in horses – definition and causes

EMS or Equine Metabolic Syndrome is a frequently diagnosed disease of affluence in horses. EMS is a metabolic disease and is defined as a symptom complex. One trigger for this symptom complex can be severe obesity in horses, which is caused by an imbalance in feeding and husbandry: too much energy from the horse’s feed and too little exercise.

This particularly affects robust horse and pony breeds such as Icelandic horses or Shetland ponies. The light-footed horse breeds are used to meagre feed in their countries of origin and require much less energy in their daily diet than other horse breeds.

In healthy horses with a needs-based diet and sufficient exercise, the glucose level or blood sugar rises during feed intake and is quickly lowered again by the hormone insulin. The sugar molecules (glucose) are transported from the blood into the cells and processed as energy during physical exertion.

However, severe obesity and a lack of exercise have a negative impact on this glucose metabolism. The excess food causes the glucose level in the blood to rise significantly, which leads to an increased release of insulin. If this high insulin secretion continues over a longer period of time, this leads to increasing insulin resistance in the cells. As a result, insulin can no longer (sufficiently) fulfil its actual function of transporting glucose from the blood into the body’s cells.

The restricted insulin action on the cells causes an increased glucose level, so that a high proportion of glucose remains in the blood vessels. This has the following consequences:

  1.  A high concentration of glucose in the blood damages the tissue in the long term. In EMS, this damage is primarily reflected in the hooves – laminitis develops.
  2. Insulin resistance leads to increased insulin secretion and large amounts of insulin in the blood (diabetes), which can also contribute to the development of laminitis.
  3. The excess energy (glucose) is absorbed by the fat cells. These work independently of insulin, so that the fat cells become significantly larger than normal. This results in the fat deposits typical of EMS on the mane ridge, above the eyes, on the chest and on the neck.
  4. Obesity leads to increased production of messenger substances in the fat cells, which can lead to inflammation throughout the horse’s body. A common form of inflammation is laminitis.
  5. The pain caused by laminitis or other inflammation triggers an increased release of the stress hormone cortisol as a reaction. This is known to increase insulin resistance. This creates a seemingly unstoppable vicious circle.

Therefore, we should try to make sure that your horse does not become overweight and does not enter this vicious circle in the first place. It is important that your horse has an ideal energy balance, i.e. an optimum balance between energy intake and energy consumption.

If your horse is already showing the first signs of EMS, an accurate diagnosis by your vet with rapid and optimal treatment are crucial.

Caution! In the case of EMS, drug treatment with cortisone is not only counterproductive, but also harmful for your horse, as the horse’s body already produces more cortisol due to the pain. Cortisol promotes insulin resistance. Therefore, if your overweight horse has concomitant symptoms such as laminitis and diabetes, you should work with your vet to investigate the causes before starting medication.

Typical symptoms and diagnosis of EMS in horses

EMS develops gradually, with symptoms that can be easily overlooked. Furthermore, EMS is a symptom complex and therefore shows many varying clinical pictures. This increases the risk of an incorrect or incomplete diagnosis.

Characteristic fat deposits appear on the mane ridge, above the eyes, on the chest, and on the neck. Other symptoms include:

  • Loss of performance, lethargy, and reduced stamina.
  • Muscle loss despite appearing “well nourished.”
  • Stiff movements.
  • Dull coat and hair.
  • Rapid and profuse sweating during light work.
  • Increased thirst and frequent urination.
  • Increased risk of infection.
  • Symptoms of laminitis.
  • Watery feces.
  • Symptoms of type 2 diabetes.
  • Fertility disorders in mares.

If your horse is overweight and also shows at least one of the symptoms listed above, you should definitely consult your vet.

Diagnosis of EMS in horses

The symptoms can indicate a variety of metabolic diseases, infections or viruses and do not always have to be the result of EMS. Equine Cushing’s disease (PPID) in particular is often confused with EMS in the early stages. Nevertheless, it is always important to consider EMS disease if your horse is overweight and also shows at least one other symptom typical of EMS.

Diagnosis is based on an assessment of the symptoms shown along with certain blood counts. In particular, the horse’s blood values are analysed for an elevated insulin level and an elevated blood lipid level. Blood tests to diagnose EMS are carried out on an empty stomach, as this is when the insulin and glucose levels are most meaningful and are not distorted by the nutritional content of the feed. It is recommended to repeat a blood test at least once every 3 weeks in case of suspicion. Some blood count values are influenced by various factors such as general physical condition, stress, the time of year or other illnesses and can be misinterpreted if performed once. Trust your vet and take your time with the diagnosis.

Treatment of EMS in horses

EMS in horses is treatable if the first signs of the symptom complex are recognised early and you optimise your horse’s situation with patience and discipline. The top priority in treatment is to optimise feeding and husbandry conditions.

The first priority is to lose the extra pounds. However, don’t put your horse on a radical diet, but let the kilos tumble in a balanced way.

  • Supplementing roughage with a balancer low in sugar and starch.  Provide your horse with sufficient low-energy roughage to promote healthy digestion. Supplement the roughage with a balancer with a very low sugar and starch content, like Thunderbrook Synergy or Daily Essentials. Are you unsure about the energy content of your roughage? Then it is best to carry out a roughage analysis.
  • Avoiding high-energy concentrates unless necessary.  Only feed a concentrate in addition to roughage if your horse really needs this energy. Then choose a low-energy and low-sugar concentrate such as Thunderbrook Healthy Herbal Muesli. However, leisure horses usually cover their energy requirements with a sufficient ration of roughage.
  • Carefully monitoring grazing to prevent high energy intake from fresh grass.  Keep a particularly close eye on grazing for EMS horses. Fresh grass in particular is very rich in energy, sugar and starch, which is not only counterproductive for your horse’s weight loss programme, but also puts a strain on its metabolism.
  • Ensuring enough exercise with a varied training plan.  Just as with us humans, a healthy diet and sufficient exercise are an ideal combination for horses to lose weight in the long term. Therefore, offer your horse enough exercise and put together a varied training plan. As with the change in feed, the same applies here: Acclimatise your horse to exercise with care. Patience is particularly important for horses that have hardly exercised before and are very overweight. Being overweight already puts a strain on the cardiovascular system and the musculoskeletal system. New movement sequences can quickly overtax your horse. In the beginning, for example, short walks are a good idea, which are then extended by approx. 10 minutes per week. As soon as your horse has lost a few kilos and is getting fitter again, you can plan a nice ride with him, integrate lunging sessions or do a few more groundwork exercises.

5 tips for preventing EMS in horses

To prevent EMS from occurring in the first place, optimal prevention is the be-all and end-all. Here are 5 tips on how to reduce the risk of EMS in your horse:

  1. Roughage as a basis

Your horse’s daily feed should consist of 70 to 100 % roughage. The raw fibres keep your horse busy, stimulate saliva production and are good for the entire digestive system. As horses spend the whole day chewing and eating, roughage containing crude fibre is the ideal feed.

  1. Consider your horse’s actual energy requirements

Only give your horse additional concentrated feed if it actually has an increased requirement. Sport horses generally have a higher energy requirement than leisure horses. However, this requirement can also change depending on the training phase. Always keep a close eye on your horse’s weight: if it is losing weight or not gaining enough muscle mass, it will need more or a different concentrated feed. If it gains weight, the amount of concentrated feed must be reduced or the type changed. Too much energy from concentrates puts a strain on your horse’s metabolism.

  1. Balancers for a balanced supply

If your horse is only fed roughage or a small amount of concentrated feed, the addition of a balancer like Thunderbrook Synergy or Daily Essentials is recommended to ensure an optimum supply of important vitamins, minerals and trace elements. With feeding a balancer your horse takes in enough essential nutrients – without any additional energy. Thunderbrook Healthy Herbal Chaff is ideal for mixing with your balancer to encourage your horse to chew and eat his feed more slowly.

  1. Consider open stable housing

Keeping your horse in an open stable with a herd offers it significantly promotes more natural movement, helping to prevent obesity. The distances to the feed and water points as well as the shelter are longer, so your horse will have to cover longer distances every day than if it were kept in a stall only.

  1. exercise, exercise, exercise!

Regular exercise keeps your horse agile and prevents it from putting on extra pounds so quickly. Just a few short daily training sessions, such as a walk, a ride or lessons in the riding arena, will get your horse moving and boost its metabolism. And at the same time, you and your horse will have a great time together!

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