Causes of laminitis can often be due to incorrect diet, usually from excessive consumption of sugars and starch in either hard feed. But most commonly from grass feeding, particularly during spring and autumn when there are flushes in grass growth. Described as a multifactorial disease, laminitis has no single trigger entirely responsible for causing the condition. There is no simple solution as a combination of factors needs to be considered.
On-going studies into laminitis look at the anatomy, diet, grazing and metabolism of glucose and insulin. Laminitis is triggered by a chain of events starting in the gut, leading to a metabolic dysfunction, which reveals itself in the feet. The cause of laminitis is frequently dietary, and the horse’s digestive system is his first line of defence.
In this article we will look at some of the feed ingredients which are currently being studied. It must be appreciated that no herb or supplement is going to be a ‘magic bullet’. But it is hoped that correct nutrition along with veterinary care, exercise and good management will help our horses.
Antioxidants are molecules capable of slowing or preventing the oxidation of other molecules. Oxidation reactions produce free radicals which start chain reactions that damage cells. Free radicals are produced naturally in the system as a result of everyday life, such as exercise or aging. But when there is excessive production the likelihood and severity of illness increases.When blood circulation is restricted, such as in the hooves during laminitis, the production of free radicals is thought to increase. This can cause significant damage both locally within the laminae and systemically. The body protects itself from free-radical damage with anti-oxidants that stabilise the free radicals so that they can no longer cause damage. Antioxidants are produced naturally by the body but during times of stress it may be necessary to supply an additional source in the diet.
Horses and ponies suffering from chronic laminitis are often maintained on restricted grazing and a limited diet. However, as fresh grass is the major source of antioxidants for horses this can have a counterproductive effect. It is therefore advisable to include a supplementary source of antioxidants in the diet of horses on restricted grazing. Antioxidants for horses are often provided in the diet in the form of trace elements such as selenium, zinc & manganese, vitamin C, vitamin E and plants with high levels of antioxidants. Anti-oxidants are not a cure for laminitis but research recommends their inclusion in the diet.
Recent research has shown a link between insulin resistance and laminitis (equine metabolic syndrome). This appears to be most likely in certain breeds of horse, such as the native breeds which are genetically adapted to live off sparse vegetation. Domesticated natives are likely to be kept on pastures much richer than they were designed to eat. This makes them more sensitive to the sugar content than other breeds. A combination of too little exercise and a diet high in grass sugars can predispose a horse to insulin resistance. This may result in a cresty neck with fat deposits over the rump and above the eyes. If the body loses its sensitivity to insulin, it will not be able to produce enough to trigger the transfer of glucose from the blood into the cells, resulting cell damage. It has been suggested that the provision of additional magnesium in the diet may help manage an insulin resistant horse. Magnesium affects both insulin secretion and action and therefore plays an essential role in glucose balance. UK forage generally provides adequate magnesium levels, but grass analysis has shown a huge amount of variation between crops. It is also well known that spring grass is often deficient. As magnesium competes with calcium for absorption sites in the gut, a high calcium diet will also reduce the amount of magnesium that can be absorbed. It is therefore good advice to ensure that a laminitic pony receives adequate levels of all vitamins and minerals, and importantly magnesium.
Like magnesium, cinnamon is also believed to help the cells to respond to insulin. So far the only studies have been carried out on humans but research has shown that cinnamon can significantly reduce blood sugar levels in people with type-2 diabetes. This is a condition linked to equine metabolic syndrome of horses, caused by insulin resistance. In the trial, 60 people with type-2 diabetes were given either cinnamon or a placebo. After 40 days those eating cinnamon showed reduced fasting levels of serum glucose by as much as 29% (Khan et al 2003). Extracts of cinnamon have also been shown to act as powerful antioxidants, which could lead to additional health benefits for the laminitic horse.
The trigger factors linking the gastro-intestinal tract with the onset of laminitis are complicated. One theory links the increase in lactic acid with the death of the healthy bacteria, resulting in the release of endotoxins into the blood stream. It is believed that these endotoxins may be responsible for the vasoconstriction of blood to the hooves. The effects of live yeast on the equine digestive system have been thoroughly researched. With our understanding of lactic acid production and laminitis, live yeast should be recommended for its positive effects on digestive balance. When live yeast is fed, the effect of excess starch consumption and acidosis on the microflora of the gut will be reduced – therefore helping to keep the gut stable. Without yeast, a high starch diet could lead to four times more lactic acid in the caecum than a high fibre diet. With this understanding of the link between digestive stability and laminitis, live yeast could be recommended for its positive effects on digestive balance. Live yeast reduces the build up of lactic acid by helping to consume the excess glucose in the gut. This will also help to mop up oxygen which is toxic to the beneficial microflora.
Our understanding of laminitis and how to manage it is improving all the time as a result of the extensive research being carried out with the collaboration of veterinarians and nutritionists across the globe. As many laminitics have to be humanely destroyed as a result of the pain rather than the condition itself, the discovery of an effective pain reliever would be a fantastic result. As the pain is neuropathic the usual anti-inflammatory drugs are ineffective. In years to come, the combination of weight control, pasture management, regular exercise and targeted nutrition should see laminitis as an easily preventable condition for most horses. For further information click on Think Laminitix Granules.
If you have any questions relating to laminitis, please call the Equi-Clinic on 01363 775 115.