Skinny or underweight horses are not uncommon. Especially during the autumn coat change and when cold temperatures put strain on the horse’s body, horses may fall below their ideal weight. Older horses also tend to lose weight more easily and do not gain it back as quickly.
A skinny horse or underweight horse is often recognizable at a glance: the ribs become visible, the flanks sink in, and the spine becomes pronounced. You can determine your horse’s weight using a livestock scale, for example. It’s also important to assess your horse’s body condition in advance, such as with the Fat Scoring or Body Condition Score system.
Why your horse may be losing weight
There are many possible reasons why a skinny horse or underweight horse may struggle to maintain a healthy weight. Inadequate feeding, excessive workload, or stress may lead to weight loss. Medical conditions such as diarrhoea, digestive disorders, and gastric ulcers are also common culprits.
A poor-quality diet that lacks protein and energy can prevent your horse from gaining weight or even cause further weight loss. This is especially true during the coat change when your horse needs extra nutrients and calories. Older horses or those with dental problems may not be able to chew or absorb food properly, which leads to nutritional deficiencies.
Understanding these causes is essential if you want to put weight on a horse effectively and safely. Feeding adjustments and proper veterinary care can make all the difference in helping a horse gain weight and thrive.
10 Expert tips to help your skinny horse gain weight
1. Provide enough high-quality forage
If you want your horse to gain weight, it must receive enough good-quality forage (grass, hay, haylage) — the rule of thumb is at least 1.5% of body weight in dry matter per day. The quality and nutritional value of forage can vary between harvests.
Always offer plenty of forage to keep your horse occupied, meet feeding needs, and support natural behaviour. Roughage should make up 70–100% of the total daily ration.
2. Supplement with forage-based products
In addition to grass, hay, and haylage, you can feed special forage substitutes — especially helpful when forage quality is poor, when there’s not enough available, or when your horse has trouble chewing (e.g. older horses with dental issues).
3. Add easily digestible feed
Supplement your forage with digestive feed products. These are easier for the horse to digest than standard grain mixes. One good option is Mash – a complete feed that’s prepared with warm water.
If you’re feeding a senior horse, add a special muesli to the forage. This palatable muesli includes digestible fibres that support a sensitive digestive system.
However, be careful not to offer your horse too much concentrate feed, as the sensitive equine stomach can become “overloaded”. Excessive amounts of concentrates can be harmful and may lead to gastric overfilling. If your senior horse has reduced dental function, it may struggle to chew coarse hay properly, which means it could be lacking in essential dietary fibre. In this case, it’s best to offer an easily chewable forage mix containing soft, short fibres. This not only promotes sufficient forage intake, but the gentle fibres also help to support your horse’s sensitive digestive system.
4. Add vegetable oil or high-fat feed
Oil provides a long-lasting source of energy for your horse. You can mix a small amount of vegetable oil into the concentrate feed or choose a horse feed with a higher fat content.
These feeds provide healthy fat to promote weight gain for horses, especially for performance horses. They are often considered the best feed to put weight on a horse.
5. Increase protein intake
A skinny horse has a higher protein requirement. If your horse needs more protein, you can supplement its diet with high-protein feeds such as Thunderbrook Gentle Gain. This product offers a natural, grain-free solution to support healthy weight gain without compromising metabolic health. This formula features the high-quality protein of ricebran and sainfoin.
Also good to know: Gentle Gain is versatile and can be fed dry or soaked, making it a convenient and palatable choice for all horses..
6. Extend turnout time
Horses often gain the most weight through grazing. Fresh grass contains more energy and protein than hay or silage. Therefore, make sure your horse can eat as much grass as possible. Many horses spend less time on pasture in winter than in summer. During the winter months, grass doesn’t grow and nutrient levels are lower. That’s why horses often lose a bit of weight in autumn and winter. Futhrermore, be mindful of the fructan content in grass during the grazing season, especially if your horse is sensitive to sugar.
7. Allow for rest and recovery
Especially with sport horses, a point is eventually reached where performance capacity hits its maximum. The same applies to feeding. There comes a time when the horse’s body can no longer absorb more nutrients, even if more is provided. For the sake of your horse’s wellbeing, it’s important to recognise this point and take a step back in your performance expectations.
8. Adapt feed to your horse’s energy needs
Horses that are expected to deliver peak performance – such as sport horses, pregnant mares or breeding stallions – have significantly higher energy and nutrient requirements. This means you’ll need to feed a more energy-dense diet.
For example: if your horse is currently being fed low-energy feed but is now entering a phase of more intense work and begins to lose condition, it’s advisable to switch to a more energy-rich feed. If your horse continues to lose weight or muscle, an even more energy-dense feed may be needed.
You can also supplement the concentrate ration with energy- and protein-rich toppers. These can be great options to support your horse’s vitality and athletic performance, and are ideal for an underweight horse that struggles to maintain weight.
9. Keep your horse warm
Make sure that underweight horses don’t have to use up valuable energy just to maintain their body temperature. They should always have access to shelter during poor weather conditions. In periods of prolonged cold and wet weather, it may be advisable to lightly rug your horse to help conserve energy.
10. Contact your vet if weight loss continues
If you’ve ruled out feeding issues and your horse is still not gaining weight, contact your vet. There may be an underlying health condition such as digestive disease or parasites.
Final Advice
If you have additional questions about feeding or caring for a skinny horse or need personalised advice on how to put weight on a horse, feel free to reach out to our Thunderbrook feeding consultants. Our experts are happy to help.