The aim of clinical nutritional management in horses, is to achieve a healthy balance between energy/nutrition, and the body of the horse. Situations that obviously lend themselves to the application of nutritional management are horses/ponies who have weight issues (i.e. over or underweight), those susceptible to laminitis, or older animals.
Laminitis, or inflammation of the laminae of the hoof, is a debilitating disease that in extreme cases can result in founder. Although laminitis occurs in the foot of the horse, there is a widely accepted linkage between instances of laminitis and the over-ingestion of water soluble carbohydrates; specifically where the diet contains enough water soluble carbohydrates(i.e. fructan) that then overloads the tolerance of the large intestine.
In looking at what dietary conditions are associated with laminitis, a UK survey of laminitic cases in the 1990's, found that 9% of the horses afflicted were stabled, 30% of the horses were on a regime of part-time stabled and part-time on pasture, and 60% of the horses were out at pasture all of the time. A similar study in the USA found that 46% of laminitic cases were linked with continuous pasture turnout. Further information tells us that the highest incidences of laminitis occurs in the spring when the pasture grass is under rapid growth and actively photosynthetic, and eager horses are ingesting more of it. This rapid growth often repeats in the fall when temperatures cool and there is more rainfall. During times when pastures are stressed, as in periods of drought, the grass plants are storing non-structural water soluble carbohydrates. Further, the amount of fructan in plants is variable both among species of plants, and different plant parts, for example ryegrass contains more water soluble carbohydrates than timothy; and plant stems contain more than the plant leaves.
While certain individual horses or ponies may be more prone to laminitis (genetic predisposition or insulin resistance), there are some basic conditions of equine feeding and management that should be considered in the avoidance of laminitis.
- Consider alternate forage arrangements other than grazing (e.g. soaked hay).
- Choose grazing times for when fructan is lowest, i.e. overnight turnout, restrict spring/autumn, or drought time grazing.
- Maintain/mow pastures to reduce mature grasses that are predominantly stems, and remove cuttings.
- Consider use of a grazing muzzle
- Reduce the size of pastures with electric cross fencing (strip grazing).
- Introduce other species to graze in rotation e.g. sheep or cattle.