Helping Your Fat Horse: A Guide to Weight Management and Better Health

Understanding Overweight Horses

Managing your horse’s weight is crucial for its overall health and well-being. This guide provides essential tips for identifying obesity in horses, understanding the associated health risks, and implementing effective weight management strategies.

By focusing on proper diet, regular exercise, and monitoring techniques, you can help your horse achieve and maintain a healthy weight, ensuring a happier and more active life.

Identifying Physical Signs of an Overweight Horse

Obesity in horses can be identified through several signs. These include:

1. The appearance of fat collections in abnormal locations such as the hollows above the eyes, along the crest (but not the rest of the neck) or in patches scattered over the body and at the tail base, often without being obese in general.
2. A horse that is extremely fat may have an obvious crease down the back, patchy fat appearing over ribs, and bulging fat around the tailhead, along withers, behind shoulders and along the neck. Fat along the inner buttocks may rub together.
3. Overweight horses may also exhibit signs of fatigue such as stumbling or tripping, elevated respiratory rate, heavier sweating, less responsiveness to cues, slowing down, and getting heavy on the forehand.
4. In some cases, overweight horses may have elevated blood insulin levels, which can be indicative of insulin resistance.
5. The development of regional fat accumulation in the hollows above the eyes, along the crest, withers, rump, tail base or chest wall is a marker of insulin resistance.

It’s important to note that not all overweight horses will exhibit all these signs, and some may not show any at all. Therefore, regular check-ups and monitoring of your horse’s weight and body condition are crucial. If you suspect your horse is overweight, it’s advisable to consult with a veterinarian for an accurate diagnosis and appropriate management plan.

A horse with a wide neck is not necessarily fat, as very heavily muscled breeds may have a crease down their back at normal body condition scores. The body bulk should be proportional to the size of the muscle mass at the upper leg/forearm/gaskin.

It also helps to look at the bone size. Lightly boned horses tend to not only carry less fat but also have the long and lean type of muscling.

A horse that is extremely fat may have an obvious crease down the back, patchy fat appearing over ribs, and bulging fat around the tailhead, along withers, behind shoulders and along the neck. Fat along the inner buttocks may rub together.

Remember, many horses that are not in high-performance activity are overweight. The horse doesn’t have to be a dead-fit athlete to have an ideal body weight. It’s simply a matter of less active horses needing fewer calories.

The Risks of Obesity

There are several risks associated with a horse being overweight or obese. Being overweight can make the heart work harder and breathing more difficult. It can also interfere with temperature regulation and put unnecessary strain on the joints, tendons, ligaments, and feet.

Every extra 100 pounds a horse carries is like carrying a full-term foal around, which can significantly affect the horse’s energy levels and overall well-being. More insidious and even more dangerous is the metabolic effect all that fat has. Obesity is associated with insulin resistance, which can lead to further health complications.[3]

In addition, overweight horses may have elevated blood insulin levels, which can lead to further health issues. If your horse is overweight or obese, it is advisable to slowly have them lose weight to mitigate these risks.

The Impact of Equine Metabolic Syndrome (EMS)

What is EMS in horses?

Equine Metabolic Syndrome (EMS) is a condition often associated with obesity in horses, but it’s not as simple as just being overweight.

EMS is characterised by three main features:

• Obesity or abnormal fat distribution,
• Insulin resistance
• Laminitis, a painful condition affecting the horse’s feet.

While obesity is a common sign, not all overweight horses have EMS. Some horses with EMS may have abnormal fat deposits, especially along the crest of the neck. However, the only way to confirm EMS is through laboratory testing, as physical characteristics alone are not definitive.

A central component of EMS is elevated insulin levels, often as a result of insulin resistance. This is caused by the failure of insulin-sensitive cells to respond to “normal” levels of insulin.

It’s important to note that EMS is not a disease, but rather a “metabolic type”. Management changes, including diet and exercise, are often necessary to control the condition and prevent further health complications.

Achieving a Healthy Weight

Where Do the Calories in Horse Diets Come From?

A common misunderstanding is that the calories in forage come only from sugars and starch. In reality, horses obtain energy from both the carbohydrate fraction and the fibre fraction of hay and grass.

Simple sugars and starch are digested in the small intestine and absorbed as glucose, producing a relatively rapid source of energy. The structural fibre components of the plant, primarily cellulose and hemicellulose, cannot be digested by the horse’s own enzymes.

Instead, they are fermented by billions of microbes in the caecum and large colon. This fermentation produces volatile fatty acids (VFAs), which are absorbed through the gut wall and provide a substantial proportion of the horse’s daily energy requirements.

The digestible energy (calories) shown on a forage analysis therefore reflects the combined contribution of both digestible carbohydrates and fermentable fibre. Different hays may contain similar calorie levels for very different reasons.

A young, leafy hay may contain more digestible sugars and highly digestible fibre, while a mature hay generally contains less sugar but also more lignin, making much of its fibre less digestible and therefore lower in energy. Short grass will be high in digestible sugar and low in fibre.

This is why simply describing a forage as “high fibre” tells us very little about its calorie content. Fibre varies enormously in digestibility depending on the maturity of the plant and its lignin content. Two hays with similar fibre percentages can provide very different amounts of usable energy.

At Forageplus, we consider the entire nutritional profile of the forage, including digestible energy, fibre digestibility, sugars, protein, vitamins and minerals, rather than focusing on a single nutrient.

Weight management is about balancing total calorie intake while ensuring the horse continues to receive adequate fibre for gut health, alongside sufficient protein, vitamins and minerals for long-term health and tissue repair.

To be obsessed with only one element of the diet at the expense of the others is not the best nutritional strategy.

The Role of Diet in Horse Weight Management

Diet plays a crucial role in horse weight management. Horses are designed to function on a high-fibre, predominantly forage-based diet. These are some of the crucial areas you need to think about:

Low Carbohydrate: Horses that are overweight generally benefit from forage with a low sugar and starch content. During spring and summer, this can be difficult to achieve because fresh grass often contains high levels of readily digestible carbohydrates and provides a significant amount of digestible energy with every mouthful.

Short, closely grazed pasture can be particularly challenging because horses consume very little structural fibre while still ingesting concentrated amounts of sugars and other non-structural carbohydrates from the young leaf tissue.

Horses obtain calories from both the carbohydrate fraction and the fibre fraction of forage. Sugars and starch are digested in the small intestine, while the fibre fraction is fermented by microbes in the hindgut to produce volatile fatty acids, which provide a major source of energy.

Fibre therefore contributes significantly to the horse’s calorie intake, but because it is fermented slowly, it produces a much steadier metabolic response than sugars and starch.

Successful weight management depends on controlling total calorie intake, regardless of whether those calories come from fibre or carbohydrates. This is achieved by feeding a measured amount of hay with a known digestible energy value while maintaining adequate fibre intake to support normal gut function.

If a hay analysis shows an ESC plus starch value below 10 percent on a dry matter basis, there is generally no nutritional reason to soak it further to reduce sugars.[4]

Soaking hay does not remove the structural fibre, but it can reduce valuable nutrients and, particularly in warm weather, increase microbial growth if it is not managed correctly.

For horses with insulin dysregulation or insulin resistance, the amount of sugar and starch consumed in each mouthful is equally important. Reducing the non-structural carbohydrate content helps minimise excessive insulin responses, while controlling the total amount of forage fed manages calorie intake.

Together, these approaches support gradual weight loss while reducing the risk of endocrinopathic laminitis.

Excessive Calories: Horses carrying excess body fat are consuming more digestible energy (calories) than they are using. Those calories come from both the carbohydrate fraction and the fibre fraction of hay and grass.

Sugars and starch provide readily available energy through digestion in the small intestine, while the fibre fraction is fermented in the hindgut to produce volatile fatty acids, which are also an important source of calories. Successful weight management therefore requires controlling the horse’s total calorie intake by feeding a measured amount of forage with a known digestible energy value.

At the same time, the sugar and starch content of each mouthful should be kept low in horses with insulin dysregulation or those at risk of laminitis, as excessive insulin responses can occur even before significant weight gain develops.

Weight Loss: Weight loss is achieved by feeding slightly fewer digestible energy (calories) than the horse uses each day, while still providing adequate protein, fibre, vitamins and minerals. The horse’s calorie requirement should be calculated according to body weight, age and workload using NRC guidelines.[2]

Because forage provides calories from both the fibre fraction and the carbohydrate fraction, the total amount of forage fed should be measured and matched to the horse’s energy requirement.

During spring and summer, grazing is usually the largest source of calories and readily digestible carbohydrates. For horses with insulin dysregulation or insulin resistance, it is particularly important to keep simple sugars (ESC on a hay analysis) and starch low to minimise excessive insulin responses and reduce the risk of laminitis.

For all overweight horses, successful weight loss depends primarily on creating a modest calorie deficit, while choosing lower sugar and starch forage can improve metabolic health and make weight management easier.

Reduce Grass Consumption: Grass is the food where horses get the most calories and carbohydrates in spring and summer. Many horses must have reduced grazing or no grazing to control fat levels.

Even horses on track systems can get too much grass. A track which has a lot of short-cropped grass, growing on compacted soil, will produce grass which is very high in sugar, especially if there is a lot of track! Short-cropped grass on tracks is also dirty.

Provide Clean Forage: Dirty grazing, where horses are nibbling short-cropped grass close to compacted soil, will affect metabolism due to mineral imbalance and exposure to microorganisms on the soil surface.

This type of grazing is unhealthy due to the soil being squashed and not supplying the plants with the right growing environment. It is better to limit access to this grazing and provide clean forage in the form of low-sugar hay.

Limit Soaking of Hay: Rinsing hay should be done for no more than one to two hours and preferably not at all. Carry out hay analysis to know if soaking is needed.

Soaking washes out minerals and vitamins, which are hard to replace, even with a balancer, especially when it is over 1 hour. The loss of these nutrients predisposes your horse to be more susceptible to metabolic dysfunction due to nutrient deficiencies.

Test Hay: Hay analysis will tell exactly how much hay to feed for weight maintenance and digestive health. Nutritional analysis will also tell you if you need to soak hay at all.

Testing will supply you with information on crucial protein levels, which impact both health and the horse feeling hungry and overeating. No more guessing and hoping what you are feeding will work!

Balance Minerals and Vitamins: The ONLY way to monitor nutritional intake is to look at what is in the grass and hay and match to that. Most horse feed balancers scattergun a bit of everything but do not look at what is needed to balance grass and hay.

This is a situation where less is more and a forage-focused approach is far superior. Don’t scattergun; target nutrition to sensitise metabolism and provide the chemistry the body needs to be lean. If you can test hay and grass for mineral levels so you can balance accurately, if not, use a truly forage-focused balancer based on data from many samples of forage.

Feed Enough Protein: Around 85% of all hay and haylage have under half the protein a horse, even in light work, needs to be healthy. [1] This means the body cannot access the protein it needs to be healthy, fat gain becomes more likely, and horses will overeat to try to get the protein they need to live.

Protein will stop your horse feeling hungry and searching to find more food so that they have enough protein. Protein levels drive appetite, so if you can feed more protein to fill the gap, then the horse will have less reason to guzzle more grass or hay.

Other supplements to help: In cases where horses are slow to respond to diet changes, certain supplements like trimethylglycine, aka betaine, can be added to the diet. This helps the cells and the kidney retain water, helping the horse to flesh out very quickly.

The Benefits of Exercise in Horse Weight Management

Exercise plays a crucial role in managing a horse’s weight. Research on exercising obese horses has shown improvements in insulin concentrations as well as reduced leptin concentrations.[5]

Below are some strategies that may be helpful to facilitate weight loss and promote healthier glucose metabolism. The strategies can be done ridden or in hand and, in some situations, as free work using positive reinforcement techniques. Veterinary supervision may be required in some cases.

Assessing and Monitoring Weight

Utilising Body Condition Scoring for Weight Assessment

Familiarise yourself with using a Body Condition Score system. The system grades the horse based on evaluation of areas where fat typically accumulates. It’s designed to specifically evaluate the amount of body fat the horse is carrying. You can also use a score to assess crest fat.

Observe your horse and palpate its body using condition scoring to assess the horse’s weight regularly. Check over the ribs, along the spine/topline, and at the hips. The coat can make it difficult to accurately see body condition, so palpation is important.

Research has shown that many owners have a distorted idea of what a healthy bodyweight actually is.[6] Therefore, it’s important to educate yourself and be very vigilant in using body condition scoring to assess if you have a fat horse.

Tools for Assessing Horse Body Condition

Use a weight tape to estimate your horse’s weight on a weekly basis and record these numbers. Weight changes can be difficult to see over time. Seeing the numbers will help you see increases and make diet changes before weight gain becomes large.

Make sure you use the weigh tape at the same time of day, and in the same way each time you use it so that there is consistency in the results. This PDF will help you do this.

Determining a Horse’s Ideal Weight

Determining the correct weight for your horse depends on several factors, including the breed, age, and individual metabolic rate.

Different breeds have different average weights. For example, a Thoroughbred may weigh between 450 to 550 kilograms, while a Shetland pony might weigh around 200 kilograms. Research the average weight range for your horse’s breed as a starting point.

Managing Weight Loss

Management Tips to Keep Your Horse at a Healthy Weight

The management of an overweight horse should focus not just on diet and supplements but also on the environment and ways to reduce calorie consumption. You must use a multifaceted plan of attack to get your fat horse to lose weight slowly. Use the diet and exercise tips above but combine them with management practises which promote the horse’s ideal body weight.

To get an obese horse to lose weight, weigh the hay that is fed to your horse using a fish or travel scale. How much hay to feed each day is dependent upon body weight and whether you know the calorie content of the hay fed. 

A rough guide if you don’t know the calorie content is to feed 2% of body weight to maintain weight, or 1.5% of body weight to lose weight.  Another approach for very obese horses is to pick a weight you want the horse to get to and feed 2% of this weight. 

You should always be aiming to feed as much forage as possible, so choose the method which supplies the greatest volume.

Use a robust slow feeder, and small-holed nets to reduce the amount of hay that the horse can get in each mouthful. This means you can put more hay into these nets knowing that it will be trickled through the digestive system, keeping it healthy.

This can help with your time management when you cannot visit your horse every four hours to replenish hay. Four hours is the longest time your horse should go with no forage to eat.

Keep track of the horse’s calorie intake to stop weight gain and compare it with the average requirements. If the horse is gaining too much weight, it might be consuming too many calories.

The easiest way to do this is to accept that your horse might have to be off grass completely so that you can calculate the hay needed to create a healthy weight. Remember that testing hay will help you KNOW how much to feed, as nutritional testing measures the calories in the hay.

If you must turn out on pasture, muzzling can be a short-term solution. There are many muzzles on the market, and they will restrict how much grass can be bitten and eaten at once, so muzzling can help control their intake. However, observe the length of the pasture carefully; if it is very short, then the muzzle should be on for no more than 4 hours.

Consider not rugging your horse in winter or rugging very minimally. When horses are not rugged, they have to use more energy to keep warm. Some horses even benefit from a minimal underneck and belly clip and no rug so they really have to use their fat reserves to keep warm.