The dangers of an overweight horse and a slimming plan to get equines into shape *H&H Plus*

  • An overweight horse is a ticking time bomb for serious health issues. Kieran O’Brien MRCVS outlines a nine-point slimming plan

    The UK equine population is in the grip of an obesity epidemic. Close to half of adult horses and ponies are overweight, studies have found, rising to nearly 70% of leisure animals.

    Obesity, a preventable condition, is a key predisposing factor in most cases of laminitis – a disease that accounts for 25% of animals euthanased for health reasons every year. It contributes to other diseases, including soft tissue injuries, osteoarthritis, and colic, and has been associated with equine asthma.

    Since obese horses (largely in the showing world) are the role models, it is not surprising that 50% of owners in a recent survey did not consider their obese horses to be overweight.

    Many obese horses, although apparently healthy, are suffering from undiagnosed equine metabolic syndrome (EMS) and live on a laminitis cliff-edge.

    Factors known to contribute to the current epidemic include a mismatch between calorie intake and workload, a tendency for owners to view overfeeding as “caring” (and, conversely, to view making necessary dietary restrictions as “uncaring”), and a failure to recognise that if a horse’s ribs are not visible or palpable, they are actually covered in fat.

    In addition, some livery yard owners will not allow the grazing and management changes required to reduce food intake.

    Size matters

    Since the cause of obesity is multifactorial, treating and preventing it must be tailored to each horse’s situation.

    Various scoring systems are available to assess fat cover objectively. On a simple five-point system, a horse scoring four (deemed fat) has well-covered ribs and hips, a firm, wide crest and an obvious gutter on his rump (an “apple bottom”). A score of five, deemed obese, indicates a firmer, wider crest, a flat back and a more pronounced apple bottom. The ideal score for a leisure horse is three; for a competition horse, two.

    To bring about a healthy, long-term change in body shape, the aim is to balance steady weight loss with welfare. Sensible steps might run as follows:

    • Make a plan: essentially, the only way to mobilise a horse’s fat is to decrease input (while maintaining adequate dietary bulk, and a balanced protein, vitamin and mineral intake) and increase output. This is achieved by restricting the amount of calories that grass or hay provide, eliminating calorie-rich feeds and increasing his workload. Start by determining his bodyweight (with a weigh tape or weighbridge), then aim to reduce this by 1% per week to the target weight.
    • Set up strip grazing: use an electric fence and move it forward a small amount every day, with a “back fence” to prevent the horse from eating the regrowth behind him. The number of piles of droppings passed when grazing is unrestricted should reduce by between a half and two-thirds when strip grazing starts. If the number doesn’t drop to these levels, the strip is too wide.
    • Select the right hay: choose the coarsest, stemmiest hay you can find. Old hay can still be high in calories; it is the age of the grass when cut and the grass species that determine calorie content. Assuming he has no access to grass, each day weigh out 2.5% (1.5% in EMS cases) of the horse’s bodyweight in hay and immerse it totally it in water, periodically agitating the net. The longer the soak, the more sugar leaves the hay – aim for at least 12 hours. Ideally, have a hay sample analysed after soaking to ensure the sugar level is not above 10%. Prolong feeding time by using a small-holed haynet, a double net or a slow feeder. Although “spoilage bacteria” may multiply in the soaking water, there is currently no evidence that these are harmful to horses. Steaming has little or no effect on calorie content.
    • Avoid haylage: although in principle the haylage fermentation process does reduce sugar content, studies have shown a surge in blood insulin after feeding haylage – for reasons as yet unknown. In addition, some “high-fibre” haylages, surprisingly, if fed at a rate to provide the recommended amount of fibre, provide sufficient calories for light work and are therefore not suitable for weight control.
    • Feed straw: if gradually introduced and if the horse has healthy teeth, replacement of a proportion of the hay ration with low-calorie, unchopped oat or barley straw can aid calorie dilution. Straw is eaten more slowly and so prolongs eating time when forage is restricted. A replacement rate of 30% by weight is acceptable.
    • Balance the diet: because the soaking process leaches out some nutrients, a low-calorie balancer ensures an adequate intake of protein, vitamins and minerals during the dieting regime. Balancers do not provide salt; if the horse is in work, add a tablespoon daily to the feed.
    • Provide exercise: light hacking is insufficient to promote weight loss; a minimum of 15 to 20 minutes of trotting per day, for five days a week, is required. Regular fast canter work should also be included. Small ponies can be exercised by being led from another horse.
    • Avoid rugging: winter rugging stops the horse from increasing his metabolic rate – and burning fat – to keep himself warm. Unless fully clipped, an obese horse needs no rug indoors, and only an unlined rug if necessary to stay mud-free during turnout.
    • Monitor progress: internal abdominal fat is consumed first. At a 12-week assessment, the body fat score and weigh tape measurement may appear virtually unchanged – even though the horse has genuinely lost weight. A better gauge is belly girth: a measurement taken around the widest part of the belly at the end of week one should have reduced significantly after 12 weeks. If it hasn’t, ask your vet to re-assess the feeding regime.

    Muzzle know-how

    Grazing muzzles have been shown to reduce grass intake by 50 to 80%, depending on the individual and the length of the grass. They enable bonded ponies to live together and interact socially, and allow more exercise than that afforded by a restricted grazing area. Not every pony will accept a muzzle, however, or learn how to use it.

    Correct fitting and training are important. Use a muzzle with protective padding, ideally, showing the pony he can still eat and drink by pushing grass through the muzzle openings. Ensure there is a gap of 2.5cm between the end of the muzzle and the pony’s teeth, and at least 2-3 fingers’ space around the sides to allow chewing. Do not leave the muzzle on for more than 10 to 12 hours at a time and check the pony regularly for rubbed areas or tooth wear.

    A muzzle cannot be combined with free grazing. Once it is removed, it is critically important the pony is not returned to the paddock – a hungry pony will then binge eat and may eat half his daily grass intake in as little as three hours. The time without the muzzle should instead be spent in a yard or bare paddock, where some hay or straw can be fed.

    If keeping the muzzle in place proves difficult, you can try:

    • Plaiting the forelock with the top of the mane, before feeding the muzzle strap through it.
    • Fitting a fly mask or safety headcollar over the muzzle.
    • Securing the Velcro attachments with rubber bands.
    • Using electric fencing to keep the pony away from fixed obstacles that he might use to help pull the muzzle off.

    Ref Horse & Hound; 6 August 2020