[Nutritional laminitis--preventive measures for the obese horse].

Nutrition-induced laminitis is often caused by i) fermentation of large amounts of carbohydrates in the hindgut (usually fructans from grass or starch from cereals), which cause the release and absorption of microbial toxins and ii) insulin resistance induced by being overweight (equine metabolic syndrome). Both causes can act together. Overweight horses with a history of laminitis need to reduce body weight to prevent further incidences of laminitis. Weight reduction occurs normally on a diet of late-cut hay, a hay-straw mixture (maximally one third straw to prevent constipation) or grass seed straw all at 1-1.2% of ideal body weight. However, this roughage allowance does not satisfy the need of horses to chew, for which it requires at least 1.5% of ideal body weight. This may lead to behavioural issues, such as allophagia and aggression, and in extreme cases, stereotypic behaviour. Starch concentrates should not be replaced with high fat concentrates. Used saw dust is recommended for bedding. The intake of grass from a pasture has to be considerably and efficiently reduced. If the horse is extremely prone to laminitis or if stable management is unreliable, abstention from grazing is recommended. Any supplements need to be low in energy, and should supply minerals and vitamins which are deficient in the diet. Some additional protein or amino acids may be beneficial. Regular exercise, such as a daily 30-minute speedy trot, improves insulin sensitivity. Exercise increases energy expenditure to a certain extent, allowing a slight increase in the roughage supply, thus alleviating the conflict between energy reduction and fulfilling the need to chew. Weight loss should be 0.5-1% of body weight per week, while at a higher rate there is a potential risk of hyperlipemia. The effectiveness of the reducing diet should be monitored regularly, either by weighing or measuring body, neck or girth circumference (aiming for a reduction of 1-2 cm per week).