Obesity in horses is a serious welfare concern affecting 30–50% of UK equine populations, with native breeds at particularly high risk. Effective obesity in horses treatment requires a comprehensive approach combining dietary restriction, structured exercise, and environmental management modifications. Excess body fat increases the risk of equine metabolic syndrome, laminitis, and insulin dysregulation—conditions that can significantly compromise your horse's health and quality of life. This article provides evidence-based guidance on recognising, treating, and managing equine obesity in line with UK veterinary standards, helping owners implement safe and effective weight loss programmes under veterinary supervision.

Understanding Obesity in Horses

Obesity in horses represents a significant welfare concern and is increasingly recognised as a major health issue within equine populations across the UK. The condition occurs when energy intake consistently exceeds energy expenditure, leading to excessive accumulation of adipose tissue. Current estimates suggest that between 30% and 50% of horses and ponies in the UK are overweight or obese, with native pony breeds being particularly susceptible.

The pathophysiology of equine obesity extends beyond simple cosmetic concerns. Excess body fat, particularly visceral adipose tissue, functions as an active endocrine organ, secreting inflammatory cytokines and hormones that can disrupt normal metabolic processes. This metabolic dysfunction increases the risk of several serious conditions, including equine metabolic syndrome (EMS), laminitis, and insulin dysregulation. EMS is characterised by obesity (particularly regional adiposity such as a cresty neck), insulin dysregulation, and a predisposition to laminitis. Research has demonstrated that obese horses show altered insulin sensitivity, with peripheral tissues becoming less responsive to insulin's glucose-regulating effects.

Several factors contribute to the development of obesity in horses. Modern management practices often involve reduced exercise, increased access to high-energy feeds, and prolonged periods of box rest or restricted turnout. Native breeds evolved to thrive on sparse vegetation and may be particularly efficient at extracting nutrients from forage, making them prone to weight gain when provided with improved pasture or supplementary feeding. Additionally, owner perception plays a crucial role, as many horse owners fail to recognise when their animals are overweight, normalising what is actually an unhealthy body condition.

It is important to note that ponies, donkeys, and postpartum mares are at higher risk of hyperlipaemia (excessive fat mobilisation overwhelming the liver) if energy restriction is too abrupt or severe. Understanding these underlying mechanisms is essential for developing effective treatment strategies and preventing the serious health complications associated with equine obesity. If your horse shows signs of laminitis (heat in the feet, bounding digital pulses, reluctance to move or turn, shifting weight between feet, or lying down more than usual), contact your veterinary surgeon immediately and provide deep bedding and strict rest whilst awaiting veterinary assessment.

Recognising the Signs of an Overweight Horse

Accurate assessment of body condition is fundamental to identifying and managing obesity in horses. The Body Condition Score (BCS) system provides a standardised method for evaluating fat coverage across specific anatomical sites. In the UK, two scales are commonly used: the 0–5 scale (Carroll and Huntington) and the 1–9 scale (Henneke). On the 0–5 scale, a score of 3 represents ideal condition, whilst scores of 4 or above indicate overweight or obese status. Key assessment areas include the neck, shoulders, ribs, back, and hindquarters.

Visual and palpable indicators of excess weight include a cresty neck (fat deposits along the crest), difficulty palpating individual ribs, fat deposits behind the shoulders, a filled-in gutter along the back, and a rounded or bulging appearance to the hindquarters. The tailhead may appear elevated due to fat accumulation, and some horses develop distinct fat pads around the mammary glands or sheath. Particularly concerning is regional adiposity, where fat accumulates in specific areas such as the nuchal ligament region (cresty neck), which is associated with increased metabolic risk. The Cresty Neck Score (CNS), a 0–5 scale specifically assessing neck fat deposition, provides a complementary tool for evaluating metabolic risk, with higher scores correlating with insulin dysregulation.

Beyond visual assessment, owners should monitor for functional signs that may indicate excess weight. These include reduced exercise tolerance, reluctance to move freely, increased respiratory effort during work, and difficulty with previously manageable activities. Some horses may show signs of joint stress or lameness due to the additional load on their musculoskeletal system.

Regular body condition scoring, ideally performed monthly by the same assessor to ensure consistency, allows for early detection of weight gain trends. Photographic records taken from standardised positions (front, side, and rear) can provide valuable documentation of body condition changes over time and help overcome the gradual nature of weight gain that may go unnoticed with daily observation.

Laminitis red flags requiring urgent veterinary attention include:

• Heat in one or more feet

• Bounding digital pulses

• Reluctance to move, turn, or pick up feet

• Shifting weight between feet or 'pottery' gait

• Lying down more than usual

• Leaning back onto heels when standing

If you observe any of these signs, contact your veterinary surgeon immediately, provide deep bedding, and enforce strict box rest until your vet has assessed your horse.

Treatment Options for Obesity in Horses

The cornerstone of obesity treatment in horses involves a multifaceted approach combining dietary restriction, increased physical activity, and environmental management modifications. Unlike pharmacological interventions commonly used in human or small animal medicine, equine obesity management relies primarily on lifestyle modifications. There are currently no veterinary medicines licensed in the UK specifically for weight loss in horses. Under the Veterinary Medicines Directorate (VMD) Prescribing Cascade, veterinary surgeons may prescribe certain medicines off-label (such as levothyroxine or metformin) for managing insulin dysregulation in horses with EMS, but these are not weight-loss drugs and must only be used under veterinary direction.

The fundamental principle underlying successful weight loss is creating a sustained negative energy balance, where energy expenditure exceeds intake. This requires careful calculation of the horse's current energy requirements based on bodyweight, activity level, and target weight loss rate. A safe rate of weight loss is generally considered to be 0.5% to 1% of body weight per week, which translates to approximately 2.5–5 kg weekly for a 500 kg horse. More rapid weight loss should be avoided due to the risk of hyperlipaemia, a potentially fatal condition where excessive fat mobilisation overwhelms the liver's processing capacity. Ponies, donkeys, and postpartum mares are at particularly high risk of hyperlipaemia and require careful veterinary monitoring during weight loss programmes.

Veterinary involvement is crucial in developing an appropriate weight loss programme, particularly for horses with concurrent health conditions or those at high risk of metabolic complications. A thorough clinical examination should precede any weight reduction plan to identify underlying conditions such as equine metabolic syndrome, pituitary pars intermedia dysfunction (PPID), or orthopaedic issues that may influence exercise capacity. Baseline assessment may include blood tests to evaluate metabolic status. For horses with suspected insulin dysregulation, dynamic testing (such as an oral sugar test) may be recommended; prolonged fasting should generally be avoided in at-risk ponies and donkeys due to hyperlipaemia risk.

Environmental management forms an integral component of treatment. This includes restricting grazing access through the use of bare paddocks, track systems, or grazing muzzles, and ensuring appropriate social interaction to maintain psychological wellbeing. Owners should be educated about realistic timescales for weight loss, as achieving a healthy body condition typically requires several months of consistent management, with some horses requiring six months or longer to reach their target weight.

Important: Do not initiate or increase exercise in horses with suspected or active laminitis without veterinary direction. Laminitis requires strict rest and veterinary management before any exercise programme can be safely introduced.

Dietary Management and Feeding Strategies

Effective dietary management represents the most critical element in treating equine obesity. The primary objective is to reduce energy intake whilst maintaining adequate provision of essential nutrients, including protein, vitamins, and minerals. Forage should form the foundation of any weight loss diet, as horses are hindgut fermenters requiring a constant supply of fibre to maintain gastrointestinal health and prevent conditions such as gastric ulceration and stereotypic behaviours.

The recommended approach involves feeding forage at a rate of approximately 1.5% of body weight on a dry matter basis as a starting point for weight loss, which typically translates to approximately 7.5 kg of dry hay daily for a 500 kg horse. Your veterinary surgeon or equine nutritionist will advise whether to base this calculation on current body weight or ideal body weight depending on individual circumstances. Forage intake should not fall below 1.5% of body weight (dry matter) without veterinary supervision, as this increases the risk of gastrointestinal complications and hyperlipaemia in susceptible individuals. Late-cut, mature hay generally contains lower levels of water-soluble carbohydrates (WSC) and energy compared to early-cut, leafy hay, making it more suitable for weight reduction programmes.

Soaking hay in cold water can reduce WSC content, which is particularly beneficial for horses with insulin dysregulation. However, the degree of sugar reduction is highly variable depending on hay type, water temperature, and soaking duration, and may range from minimal to approximately 30% reduction with longer soaks. Soaking also leaches water-soluble vitamins and minerals and requires careful hygiene to prevent microbial contamination. If soaking hay, weigh it before soaking to calculate the dry matter accurately, as soaked hay will be heavier due to water absorption. Haylage should be used with caution in obese or insulin-dysregulated horses, as WSC and energy content can be variable and difficult to assess without laboratory analysis.

Concentrate feeds should be eliminated or drastically reduced for most overweight horses, as these provide concentrated energy that is counterproductive to weight loss. Many obese horses can maintain condition and lose weight successfully on a forage-only diet. However, when forage quality is poor or intake is restricted, a low-calorie balancer or vitamin and mineral supplement should be provided to prevent nutritional deficiencies, particularly of protein, lysine, copper, zinc, and selenium.

In some cases, veterinary surgeons or nutritionists may recommend partial substitution of hay with good-quality straw (typically up to approximately 30% of forage dry matter) to reduce dietary energy density, though this must be introduced gradually and monitored carefully due to the risk of impaction colic.

Feeding management strategies can enhance the effectiveness of dietary restriction. These include:

• Using small-holed haynets (3–4 cm mesh) or slow-feeder systems to extend eating time and reduce consumption rate

• Dividing daily forage allocation into multiple smaller portions to maintain more consistent gut fill

• Weighing all feed (dry, before soaking) to ensure accurate ration provision, as visual estimation is notoriously inaccurate

• Removing or severely restricting access to grazing, particularly during spring and autumn when grass WSC content is highest

• Using grazing muzzles correctly: ensure proper fit to prevent rubbing, limit use to a maximum of 10–12 hours daily, check regularly for sores, and ensure the horse can drink water whilst wearing the muzzle

• Avoiding all treats, including carrots, apples, and commercial treats, which provide unnecessary calories

The British Horse Society's 'Right Weight' programme provides practical UK-specific guidance and monitoring tools for owners implementing weight loss programmes.

Exercise Programmes for Weight Loss in Horses

Structured exercise programmes complement dietary restriction by increasing energy expenditure and improving metabolic health, cardiovascular fitness, and musculoskeletal function. However, exercise alone is insufficient for significant weight loss without concurrent dietary management, as horses can easily consume more energy than they expend through activity. The exercise programme must be tailored to the individual horse's current fitness level, any existing health conditions, and the severity of obesity.

Important: Do not exercise horses with suspected or confirmed laminitis until cleared by your veterinary surgeon. Active laminitis requires strict rest, and exercise can worsen the condition and cause permanent damage.

For severely obese or previously sedentary horses without laminitis, exercise should be introduced gradually to avoid injury and excessive strain on joints, tendons, and the cardiovascular system. An initial programme might begin with 10–15 minutes of walking in-hand or under saddle, performed 4–5 times weekly. This duration can be progressively increased by 5-minute increments every 1–2 weeks as fitness improves, with the ultimate goal of achieving 30–45 minutes of continuous exercise daily. Walking on varied terrain, including inclines where available, increases energy expenditure compared to flat work. Choose appropriate footing (avoid deep or hard surfaces) to reduce injury risk.

As fitness develops and weight decreases, the intensity and variety of exercise can be increased. Introducing periods of trot work, pole exercises, and hill work further enhances calorie burning and muscle development. For horses unable to be ridden due to excessive weight or orthopaedic concerns, alternatives include in-hand walking, long-reining, or the use of horse walkers. Lungeing should be used with caution and only for very short periods initially, as it increases loading on the inside limbs and can be particularly stressful for obese or unfit horses; in-hand walking is generally safer.

Turnout, whilst not constituting formal exercise, contributes to overall activity levels and energy expenditure. Horses maintained on restricted grazing areas or track systems naturally increase their movement as they travel between resources such as water, shelter, and feeding stations. Group turnout can encourage activity through social interaction and play behaviour, provided that bullying or feed competition does not occur.

Owners should monitor their horse's response to exercise carefully. Simple monitoring includes checking for:

• Normal recovery of heart rate and respiratory rate within 10–15 minutes of finishing exercise

• Absence of heat in the feet or increased strength of digital pulses after exercise

• No signs of excessive fatigue, increased respiratory effort, or lameness

Any concerns should prompt veterinary consultation, and exercise intensity should be reduced if adverse signs develop.

Monitoring Progress and Long-Term Weight Management

Systematic monitoring is essential for evaluating the effectiveness of weight loss interventions and making necessary adjustments to the management plan. Regular body condition scoring, performed at consistent intervals (typically every 2–4 weeks), provides a practical method for tracking progress. Using the same assessor and maintaining photographic records enhances objectivity and helps identify subtle changes that may not be apparent through daily observation. The British Horse Society's 'Right Weight' programme provides monitoring charts and guidance for UK owners.

Weighing provides the most accurate assessment of weight change, though access to suitable weighbridges or livestock scales may be limited. Where available, monthly weighing is recommended. Weight tapes offer a more accessible alternative, though they are less accurate and can underestimate weight in obese horses. To improve consistency, use the same tape, at the same time of day, with the same handler, and ensure the horse is standing square on level ground. Girth and height measurements, recorded at standardised anatomical landmarks, can supplement body condition scoring and provide additional objective data.

If adequate progress is not achieved after 4–6 weeks of consistent management (indicated by no change in body condition score or weight), the programme requires modification. This may involve further reducing forage intake (whilst maintaining a minimum of 1.5% body weight dry matter and only under veterinary supervision), reassessing forage quality and energy content, increasing exercise duration or intensity, or investigating potential underlying metabolic or endocrine disorders. Conversely, if weight loss exceeds 1% of body weight weekly, energy intake should be slightly increased to prevent hyperlipaemia risk. In high-risk individuals (ponies, donkeys, postpartum mares), consider veterinary assessment including serum triglyceride measurement if rapid weight loss occurs.

Long-term weight maintenance following successful weight loss requires ongoing vigilance and commitment. Many horses will require permanent modifications to their management, including continued grazing restriction (particularly during high-risk periods in spring and autumn), and maintenance of regular exercise routines. The target body condition score of 2.5–3 (on a 0–5 scale) or 5–6 (on a 1–9 scale) should be maintained through regular monitoring and prompt intervention if weight gain is detected.

Owner education plays a vital role in long-term success. Understanding that obesity is a chronic condition requiring lifelong management, rather than a temporary problem with a finite solution, helps maintain compliance with management recommendations. Regular veterinary reviews, ideally annually or when management changes are contemplated, support sustained weight control and allow early identification of metabolic complications.

When to seek specialist referral:

• Failure to lose weight despite consistent management over 3–6 months

• Recurrent laminitis episodes

• Suspected or confirmed equine metabolic syndrome or pituitary pars intermedia dysfunction (PPID) requiring advanced diagnostic testing or complex management

• Severe insulin dysregulation

Your veterinary surgeon can refer your horse to an RCVS Advanced Practitioner in Equine Internal Medicine or a European College of Equine Internal Medicine (ECEIM) Diplomate for specialist assessment and management. Establishing realistic expectations and celebrating incremental progress helps maintain motivation throughout what can be a lengthy process, ultimately improving the horse's welfare, longevity, and quality of life.

Frequently Asked Questions