Discussion

Take home message:
Pasture turnout can be a trigger factor for laminitis even in the lean, nonobese animal, which does not have raised basal plasma insulin concentrations. Obesity may increase the risk, as does turning out on a pasture with high nonstructural carbohydrate content (NSC: simple sugars, fructans, and starch).

Take home advice:
Based on existing knowledge and scientific reports the following is recommended. The actual programme will need to be tailored for the individual horse/pony. Consultation with a suitably qualified nutritionist may be helpful, especially in problem or recurrent cases.
- Base the diet on forage/fibre.
- Especially for recurrent sufferers, analyse the forage and feed a <10% NSC forage. Many hays will be higher than this. Soaking hay in clean water (ideally around 16degreesC: summer tapwater) for ~3 h may help to reduce the water-soluble carbohydrate (WSC: sugar and fructan) content. However, results from soaking are variable, therefore, if concerned, ensure the original forage has a low NSC content or feed an appropriate forage replacer.
- Feed a broad-spectrum vitamin and mineral supplement if no or low levels of complementary feed are given (i.e. forage is the main component of the diet). Ensure an adequate and balanced intake of magnesium (recommend between 0.02 - 0.03 g/kg bwt). There is no current evidence, however, to suggest that high levels of magnesium will be protective and reduce the risk of laminitis.
- It may be helpful to provide additional biotin, on top of a ration providing sufficient amino acids, zinc and calcium etc., in order to help support optimal hoof growth and quality.
- Feeding bran mashes (especially when fed solus with forage) is likely to be contraindicated particularly for animals unaccustomed to bran. Bran can be an irritant to the GIT, has an imbalanced Ca:P ratio and nutritionally is deficient in many key nutrients such as lysine.
- Ensure that laminitis prone animals are provided with intakes of Vitamin E, for example, that would be more appropriate for the athletic animal (3 - 4 iu/kg bwt).
- For many animals additional energy sources will not be required.
However, for those requiring additional energy, consider:
- The use of more digestible forage (i.e. less mature grass hay) - although recommend avoiding feeding alfalfa or haylage to animals that are prone to laminitis. High NSC hays should still be avoided (see above).
- Highly digestible fibre sources such as unmollassed sugar beet pulp or soya hulls. Recommend soaking and throwing away the water even from unmolassed sugar beet pulp to reduce as far as possible the WSC (and fructose) content.
- If there are no contraindications, using vegetable oil as an additional energy source rather than cereal starch - especially for those animals not being exercised (remember to add gradually, balance the overall diet and add additional Vitamin E at 1 - 1.5 iu/ml of oil). As a guide limit to <1ml oil/ kg bwt unless undertaking more in- depth nutritional evaluations.

- If any cereals, other than oats, are fed make sure they are processed by cooking (e.g. steam flaked, micronised) to make the starch more easily digested, reducing the risk of starch overload. Avoid feeding large grain based meals: restrict meal sizes to <0.3 kg/100 kg bwt of a cereal- based feed. For all horses ensure overall starch/sugar intake is <1 g/kg bwt per meal. NB: cereal based rations are very unlikely to be a recommended feeding programme for animals prone to laminitis.
- Ideally ensure any meal/forage fed is sufficiently small in size and low in starch/sugar content so that it only produces a low to low-moderate insulin response.
- Make all dietary changes slowly and avoid abruptly starving animals, especially when pregnant or sick, or preventing them from eating for prolonged periods (potential increased risk of hyperlipaemia).
- Ensure high levels of general care especially hoof maintenance and anthelmintic use.
- Maintain and increase regular exercise wherever possible
(especially if overweight).
- Avoid development of obesity: aim to maintain a moderate body condition score around 5 (/9). For overweight animals, plan an active weight management programme, linked with increasing exercise whenever possible. Set realistic targets and monitor the animal's weight and condition on a regular basis.

Turn-out:
- Consider zero grazing (whilst providing suitable forage alternatives) if it is essential that the horse ingests minimal levels of NSC or a strict weight management programme is needed.
- Turn out to pasture when fructan/WSC levels are likely to be at their lowest, such as late at night to early morning, removing from the pasture by mid-morning.
- Do not graze on pastures which have not been properly managed by regular grazing or cutting. Try to maintain a young leafy sward as mature stemmy grasses contain higher levels of stored fructans. NB caution re herbage yield i.e. large intakes of a low/moderate NSC pasture may be as problematical as small amounts of a high NSC pasture.
- Avoid/restrict turning out in spring (before flower development) and autumn. At any time, consider restricted turnout to pastures during flowering and early seeding.
- Do not graze on pastures that have been exposed to low temperatures (e.g. frosts) followed by warm, bright sunny days or those that have been 'stressed' through drought.
- Consider maintaining turnout by use of grazing muzzles (ensure that horses can obtain sufficient water intake and be aware of possible behavioural issues); strip grazing behind other horses; mowing and removing clippings; putting a deep layer of wood chips over a small paddock or using dry lots (weed control essential)/indoor schools etc. Caution when feeding restricted forage intakes on sandy pastures etc. re potential increased risk of sand colics/shavings ingestion.
- Rotate use of paddocks regularly, preferably with other species such as sheep or cattle, to keep the grass levels at an appropriate height to avoid the paddocks becoming 'stressed' through either under or over-grazing.