The threat of laminitis

The recent death of the high-profile Thoroughbred stallion Machiavellian from laminitis brings this debilitating condition to the fore once again, and clearly demonstrates that its victims extend beyond native ponies and show animals.

Racehorses and competition animals can be susceptible to the condition due to the concussive effects of their high-impact workload and because their typical diet can bring on laminitis at the time and, if fed long term, may precondition them to the disease in later life.

The dietary launchpad for laminitis is the overflow of starch or sugar in to the large intestine, resulting in an unhealthy disruption to the ongoing fermentation of fibre there. Research opinion is still divided as to how this causes inflammation in the feet, but there is no doubt that it does.

Low-forage, high-starch diets can create these dangerous conditions, as can a huge sugar (including fructan) overload from sudden access to rich new grazing.

Starch in the hindgut is abnormal and disrupts the function of this part of the digestive system. When starch reaches the hind gut it is converted in to lactic acid, rather than the normal volatile fatty acids which are generated by fibre. The rise in acid levels kills the microbes in the gut and the metabolic aftershock of this can cause laminitis.

Preventative measures

• Make changes gradually: horses can cope with starch and sugar in the diet as long as it is moderate amounts and not introduced quickly
• A change in forage to one that is less palatable or even to a new batch that is much wetter can lead to an unseen drop in fibre intake, bringing a horse closer to the danger zone
• High-oat diets are high-risk diets: 5kg oats will supply a massive 2kg of starch per day
• A step up in hard feed as work increases usually means that forage intakes drop — particularly dangerous if the feed is high in starch (more than 30%)
• Overfeeding: offering that extra pound of a high-starch conditioning or breeding feed or oats can tip horses over the edge
• The first telltale signs that there might be a problem are loose droppings, loss of action and irritability (resulting from a sore gut)
• This feature was first published in Horse & Hound (29 July, 2004)