Helping your pony lose weight

The science and practice of equine weight management

My pony Turbo has been overweight for most of the time I’ve had him. It’s a constant struggle to manage his weight and, as a consequence, I’ve spent a considerable time researching equine obesity and weight loss strategies in the past few years.

(You’ll find an update on Turbo’s weight loss journey at the bottom of this post!)

I know many owners struggle with this issue, so I decided to compile some of the available science and practical resources in a post. Hopefully this will be a useful guide for anyone trying to figure out a reliable, evidence-based approach.

Obesity is a growing problem

At least one third of the UK horse population is obese¹. It’s very much an equine disease of affluence, caused by the fact that our horses consume more calories than they need to in relation to the work we ask them to do.

In a natural state, horses vary their body mass with the seasons, losing weight during the winter and regaining it during the summer. This cyclical pattern is disrupted in modern management systems, with year-round access to high-nutrient forage and little need for thermoregulation because of shelter, stables, rugs etc.

In addition, horses and ponies don’t work as much today as they have in the past. Many are kept simply as pets or leisure horses, and are no longer made to march with the cavalry, plough the fields, or pull coal out of the mines.

Simply put, modern horses and ponies consume more calories than they need, and the result is an increase in weight through excess fat tissue. Obesity is generally defined as having over 20% body fat, and is more prevalent in native breeds (which have adapted to survive in harsh conditions), and in horses and ponies that do light work².

Obesity is a serious health concern

The risks associated with obesity should be of serious concern to horse owners. Being overweight adds extra stress on the horse’s hooves and joints. In addition, there is an association between obesity, insulin dysregulation, and endocrinopathic laminitis³, although the relationship between obesity and disease is complex: not all obese horses get sick, and not all sick horses are obese.

The science of weight loss

The weight loss equation is, on the surface, deceptively simple: eat less and exercise more. A negative energy balance, where horses and ponies burn more calories than they consume, will lead to progressive weight loss. Overweight ponies can lose about 1% of their body mass per week on restricted feed⁴ even with no exercise provided.

So why do I say it’s deceptive?

Because that rate of weight loss requires limiting feed intake to around 50-70% of maintenance requirements. In the study referenced above, for example, the ponies were fed only 1% of their body mass in dry matter per day. To put that in perspective, a horse or pony can consume between 2-2.5% when provided with ad lib forage⁵, and sometimes more⁶.

Restricting forage intake puts horses and ponies at risk of other problems like ulceration of the stomach, colic, and behavioural issues associated with both hunger and lack of foraging opportunitites, such as aggression and stereotypical behaviours.

Dieting your horse or pony by suddenly and severely restricting their forage intake is therefore not something I recommend. When implementing weight loss programs for equines we need to consider their physiology and their behavioural needs. Weight loss should be slow and consistent.

Involve your team

Feeding is about so many things: nutrition, health, behaviour… Getting the advice of professionals is always a good idea.

• A qualified equine nutritionist can help you develop a bespoke feeding plan for your horse or pony.

• A vet can advise you about any health risks associated with obesity and/or dieting, such as EMS, laminitis, and colic.

• An ethologist or qualified behaviourist can help you make sure you provide for your horse’s basic behavioural needs.

Now on to the practical part!

Weight loss in practice

Here are some science-backed measures you can take to help your horse or pony lose weight, while making sure other aspects of their welfare aren’t compromised in the process.

1. Find out how much your horse or pony actually eats. Analyse your hay so you know the dry matter and energy content, weigh the daily rations, and calculate the total amount of dry matter and energy your horse or pony consumes in a day. This will give you a baseline when deciding on suitable changes to the diet. A frequent recommendation for weight loss is to feed 1.5% of body weight in hay⁷, but I would recommend cutting down on forage intake gradually and consulting with a qualified nutritionist and/or your veterinarian.

2. Reduce or eliminate concentrated feed. The first thing you should remove from your horse’s or pony’s diet is concentrated feed. Do not limit their forage intake before you eliminate concentrates!

3. Replace some of the hay with straw. Straw has a lower energy content than hay; about 6 MJ metabolizable energy per kg dry matter, compared with hay which generally has about 10 MJ or higher. It also takes longer to chew, which means you can decrease your horse's energy consumtion while maintaining forage intake and eating time, which helps mitigate some of the risks with dieting (see above). Several studies have found that replacing up to half of the hay ration with straw is a safe and effective way to help horses lose weight⁸. Make sure the straw is fresh and of good quality, with no signs of dust or mold.

4. Soak the hay. Soaking hay for 12-16 hours significantly reduces the amount of nonstructural carbohydrates in it⁹.

5. Feed hay and straw in small-mesh nets. This will increase eating time, further mitigating potential adverse effects of limiting the amount of forage.

6. Give a protein supplement. Reducing the amount of forage your horse or pony eats will inevitably reduce the amount of nutrients they consume. Make sure you provide an adequate amount of supplementary protein to avoid muscle loss instead of fat loss, as dieting can cause muscle catabolism¹⁰.

7. Give a vitamin and mineral supplement. As above, reducing the amount of forage will also reduce the amount of important micronutrients your horse gets. If you soak the hay, there is likely additional loss of water-soluble vitamins and minerals¹¹. Feed an appropriate balancer to make sure your horse still has all his basic nutritional needs met.

8. Use a grazing muzzle. If you keep your horse or pony on grass, a grazing muzzle can reduce the amount of grass they eat in a given amount of time with up to 80%¹². There are, however, some important caveats: first, make sure the muzzle fits comfortably without chafing, and that your horse or pony can drink while wearing it. Second, they must have it on all the time they’re on grass, because once the muzzle is taken off, they can quickly compensate by eating A LOT in a very short amount of time - as much as 1% of their body weight in as little as three hours, according to one study¹³ (to put that in perspective, 1% of body weight in dry matter was the total amount ponies in a weight loss study were allowed to eat per day¹⁴). Third, the muzzle limits their ability to engage in mutual play and grooming sessions with friends - an important behavioural need - and this should be taken into account when planning grazing times. I do not recommend having a muzzle on 24/7. You should instead try to bring the herd in from the grass field into a grass-free area for part of the day to allow them to socialize properly.

9. Utilize thermoregulation to help burn calories. A horse coat is awesome insulation. Therefore, clipping the neck, chest, and belly (strip, trace or Irish clips, for example) of an overweight horse or pony can force them to use energy to keep warm during the winter months, aiding in their weight loss¹⁵. If you do clip, leave a protective layer on the back and hindquarters and resist rugging, as that will negate the effect of the clipping. As always, common sense should prevail: make sure your horse has adequate shelter on rainy and windy days, and take steps to make them comfortable if they are visibly cold.

10. Exercise your horse. If your horse or pony is able to exercise, then working them will be the last piece of the weight loss puzzle. Exercise can both help reduce weight and improve insulin sensitivity¹⁶. However, it can be tricky to achieve the level of energy expenditure necessary to see any positive effect, especially in horses and ponies that are neither ridden nor driven. In studies that have demonstrated improvements in insulin regulation, the horses' heart rates were increased to 140 bpm. But ANY exercise is better than none, so here are some ideas how you can increase your horse's or pony's energy expenditure:

    • Walk/ride uphill (if you only have a tiny hill, do it several times in a session)

    • Walk/ride in uneven terrain (and I mean properly uneven, shrubs, rocks, branches - really make them use their body)

    • Go for a jog with your horse or pony to help them work up a sweat

    • Walk/ride through knee-high water (sea or lake or river)

    • Turn your horse out 24/7 (this will both increase their daily movement and make them use more energy to thermoregulate)

    • Does your horse or pony know how to drive? Pulling a cart (or a log, or a tire, or anything that adds some resistance) can help increase the effort of a walk

So there you have it - a summary of the available evidence and some practical tips. Unfortunately, as you can see, there doesn’t seem to be any magic solution other than hard work.

I have not come across any evidence that supplements or alternative therapies have any measurable effect on weight loss. If you have, or if there’s anything else I’ve missed, please drop a comment below or send me an e-mail and I’ll update the post!

One final note: if your horse or pony is struggling to lose weight despite consistent efforts, speak to your vet who may advise you to test for Equine Metabolic Syndrome.

Turbo’s journey

Turbo has been overweight for most of his life (he was born in 2014). In February 2023 he was diagnosed with Equine Metabolic Syndrome (EMS) after a - thankfully very mild - laminitis scare, probably brought on by a combination of events.

EMS is associated with insulin dysregulation - you can simplistically think of it as an equine version of diabetes. One of the symptoms of EMS is weight loss resistance, which explains why it’s been such a struggle to keep him at a healthy weight.

Still, this is his progress from February 2023 to April 2023:

Turbo in February 2023

Turbo in April 20203

If you examine the before and after photo above, you can clearly see that he’s slimmed down overall. The weight tape has gone down from 350kg to 298 kg (weight tapes are not accurate for weight assessment, but I find they can give an indication of weight loss progress when used regularly), and I can feel his ribs and hip bones now.

Most importantly, there’s a visible reduction in the fat deposits on his rump and back, as well as a reduction in the size of his neck crest. Targeting the fat deposits is essential when managing an EMS horse or pony.

In addition, he’s overall healthier: more energy, less grumpy, better hoof health.

This was achieved by - you guessed it - restricting his calorie intake.

In February, we moved from a track system with free access to hay to our own yard. Here, we have grass fields and the option of stabling them at night. From a weight loss perspective, this is much better.

Essentially, what I’ve been doing is letting Turbo out to graze with a grazing muzzle during the day, and stabling him with wheat straw at night. In addition, he’s on a balanced diet making sure he gets all neccessary macro- and micronutrients.

Some days they have been out 24/7, and he’s coped fine with that, which is hopeful for summer. My priority for spring is to get him to lose weight ahead of summer and keep his sugar intake limited to minimize the risk of laminitis.

He still has a way to go in terms of weight loss, but I am now trying to increase his exercise levels rather than further restrict his feed intake, so that he can hopefully stablise at a healthy weight. It will be an ongoing management issue, but for now, we have a system that seems to be working really well.

Two more progress photos for inspiration:

February 2023

April 2023

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Here are some further resources that you may find useful:

BEVA Equine Weight Management Guide

Boehringer Ingelheim Laminitis Assessment Checklist

Boehringer Ingelheim Equine Cushing’s Disease Assessment Checklist

Redwings Horse Body Condition Score Chart

Equine Endocrionology Group recommendations for EMS horses and ponies

1. Robin CA, Ireland JL, Wylie CE, Collins SN, Verheyen KLP, Newton JR. 2015. Prevalence of and risk factors for equine obesity in Great Britain based on owner-reported body condition scores: Prevalence of and risk factors for equine obesity in Great Britain. Equine veterinary journal, 47 (2), 196-201

Dosi MCM, Kirton R, Hallsworth S, Keen JA, Morgan, RA. 2020. Inducing weight loss in native ponies: is straw a viable alternative to hay? Veterinary Record, 187 (8), 60-60

2. Knowles EJ, Grieve L. 2020. Clinical insights: Equine obesity. Equine Veterinary Journal, 52, 635–638

3. Knowles and Grieve, 2020 (see full reference above)

4. Dugdale AHA, Curtis GC, Cripps P, Harris PA, Argo CMcG. 2010. Effect of dietary restriction on body condition, composition and welfare of overweight and obese pony mares. Equine Veterinary Journal, 42 (7), 600-610

5. Morgan RA, Keen JA, McGowans CM. 2016. Treatment of equine metabolic syndrome: A clinical case series. Equine Veterinary Journal 48, 422–426

6. Longland AC, Barfoot C, Harris PA. 2016. Effects of Grazing Muzzles on Intakes of Dry Matter and Water-Soluble Carbohydrates by Ponies Grazing Spring, Summer, and Autumn Swards, as well as Autumn Swards of Different Heights. Journal of Equine Veterinary Science, 40, 26–33

Giles et al., 2014 (see full reference above)

7. Morgan et al., 2016 (see full reference above); American Association of Equine Practitioners; British Equine Veterinary Association

8. Jansson A, Harris P, Davey SL, Luthersson N, Ragnarsson S, Ringmark S. 2021. Straw as an Alternative to Grass Forage in Horses—Effects on Post-Prandial Metabolic Profile, Energy Intake, Behaviour and Gastric Ulceration. Animals, 11, 2197

Dosi et al., 2020 (see full reference above)

9. Morgan et al., 2016 (see full reference above)

10. Dugdale et al., 2010 (see full reference above)

11. Morgan et al., 2016 (see full reference above)

12. Longland et al., 2016 (see full reference above)

13. Longland et al., 2016 (see full reference above)

14. Dugdale et al., 2010 (see full reference above)

15. World Horse Welfare; British Equine Veterinary Association

16. Morgan et al., 2016 (see full reference above)