Feeding Horses and Ponies prone to Laminitis
Anyone that has owned or cared for a horse or pony with laminitis will know what a painful and debilitating condition it can be. Laminitis can simply be described as inflammation of the laminae – the soft tissue that attaches the pedal bone to the hoof wall. In severe cases, failure of this bond may cause rotation and sinking of the pedal bone, potentially penetrating the sole of the foot.
Laminitis should be regarded as a syndrome rather than a disease in its own right and although commonly considered as a condition ‘of the feet’, it is merely expressed in the feet and is likely to be the result of a complex cascade of events which may involve multiple systems within the body. Factors that may increase the risk of nutritionally related laminitis include:
- Genetics i.e. pony or native breeding (Luthersson et al 2016)
- Recent weight gain or obesity (BCS >7) (Wylie et al, 2013)
- Regional fat depots including a cresty neck
- Previous laminitis
- Overload of non-structural carbohydrate (NSC) which includes starch, sugar and grass fructans, particularly seen after a change in grazing
- Pituitary Pars Intermedia Dysfunction (PPID), also known as ‘Cushing’s syndrome’
- Insulin dysregulation - a collective term used to describe high circulating blood insulin levels and/or an increased insulin response to a starch/sugar load and/ or insulin resistance.
- How diet may increase the risk of laminitis
Laminitis continues to be the subject of much research and whilst several theories for potential causes have been identified, the exact mechanism and how they may relate to each other is still not fully understood; including the reason why some horses develop laminitis and others do not.
- Starch overload:
Horses evolved to consume and therefore digest limited amounts of starch. Undigested starch entering the hindgut as a result of feeding large cereal based meals is rapidly fermented, resulting in increased acidity and a drop in pH. The subsequent upset to the microbial population, together with lining of the digestive tract being compromised, may allow for the absorption of potential trigger factors through the gut wall.
overload Unlike starch and sugar, grass fructan is predominately digested by microbial fermentation in the large intestine and whilst this not unnatural to the horse, it is thought that domesticated horses may consume larger quantities of fructan than their wild counterparts which can lead to similar problems as starch overload.
- Obesity & regional adiposity :
Obesity & regional adiposity can be associated with a pro-inflammatory state, insulin dysregulation and an increased risk of laminitis although the exact links remain unclear.
- Insulin dysregulation
Insulin dysregulation has been associated with an increased risk of laminitis although the mechanism for this is still not clear. Our research has shown that weight gain as a result of increasing energy (calorie) intake from cereals results in decreased tissue insulin sensitivity in adult horses whilst increasing energy intake from oil does not.
- Starch overload:
- How you can help
Whilst science continues to both further our knowledge and raise more questions, nutritional management of horses and ponies should focus on managing as many of the risk factors as possible.
- Managing forage intake:
Restricting or removing access to pasture helps to reduce water soluble carbohydrate (sugar + fructan) intake. Whilst spring and autumn are considered ‘high risk’ periods, a recent study found that an increase in grass quantity or quality significantly increases the risk of laminitis, regardless of the season (Luthersson et al 2016). Forage for laminitics should contain less than 10% WSC although levels in hay and haylage can easily exceed this. Whilst soaking hay may reduce WSC, results are variable and cannot guarantee suitability for laminitics. Ideally consider having your forage analysed and where possible, choose a low WSC hay rather than a low WSC haylage. Alternatively speak to a nutritionist on feeding a hay/ forage replacer known to contain low levels of starch, sugar and fructan.
- Monitor body condition score (BCS):
Aim to maintain a BCS 4.5-5 on a 1-9 scale. Forage alone can easily meet or exceed the energy (calorie) requirements for many horses, but is unlikely to provide a balanced supply of vitamins, minerals and amino acids – the building blocks of protein. In these situations contact a nutritionist for advice on feeding a balancer.
- Reduce starch intake:
If forage alone does not provide the energy required to maintain condition, avoid cereal grains and choose fibre based feeds which ideally have a combined starch and sugar content of less than 10%. Gram for gram, oil is approximately 2.5 times higher in energy compared to cereals and starch free, making feeds high in fibre and oil a sympathetic alternative to traditional, cereal based options.
- Managing forage intake:
- Luthersson N, Mannfalk M, Parkin TDH, Harris P, Laminitis: Risk factors and outcome in a group of Danish horses, Journal of Equine Veterinary Science (2016), doi: 10.1016/ j.jevs.2016.03.006
- Wylie, C. E., Collins, S. N., Verheyen, K. L., Newton, J. R., 2013. Risk factors for equine laminitis: a case-control study conducted in veterinary-registered horses and ponies in Great Britain between 2009 and 2011. Veterinary Journal 198 (1), 57-69.