It is worth recognising that while there is much we still don't understand about the mechanisms whereby an upset in the horse's hindgut can lead to the devastating changes in its feet caused by laminitis, if everyone applied the knowledge we do have, then the incidence of laminitis would be reduced by about 80%. Put simply, allowing horses and ponies unrestricted access to improved pastures is putting them at high risk of developing laminitis. Intentionally fattening them up for showing is just asking for trouble.

 

A significant development this year is the Laminitis Trust Horse Feed Approval Mark scheme (UK). This mark is granted by the Scientific Committee of the Laminitis Trust to identify feeds which are considered suitable to help prevent laminitis or to feed to animals which are suffering from laminitis. Feed manufacturers have to present information on submitted products in considerable detail, including feed ingredients, analysis, production details and quality control procedures. It is hoped that worried owners will use feeds carrying the mark to gain some peace of mind when wondering what to feed in the face of the huge variety available.

 

I personally regard all over-the-counter laminitis preventers, easers or so-called 'cures' with suspicion. This is not because of what they contain but because none of them have any scientific evidence to demonstrate their efficacy. Therefore owners, in buying these products, will be lulled into a false sense of security.

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However, work in Australia has led to a product, the only product, which has been proven to prevent dietary laminitis.***

The product is called Founderguard and it contains a tiny dose of an antibiotic, virginiamycin, in a special formulation which allows its release in the hindgut of the horse. Virginiamycin, providing it is present in the hindgut when an excess of soluble carbohydrate enters, prevents laminitis either following grain overload or in Australian grazing conditions. Its efficacy in British grazing conditions is currently under study in the UK, with over 150 veterinary practices using the product. It is recommended that Founderguard be introduced gradually, and it is not suitable for use in breeding animals. It must be remembered that Founderguard is only effective at preventing laminitis; it is no use as a treatment. In addition owners must realise that it is only effective if the laminitis is due to carbohydrate overload, i.e. it will not work if laminitis is due to one of the other causes (see later).

Founderguard, is only available through veterinary surgeons and requires a Special Treatment Authority (STA) from the Ministry of Agriculture. This is because it does not have a product licence due to EU veterinary medicines rules. However, we are fortunate that our Ministry has let Founderguard be available through the STA route; some countries are not so lucky. Veterinary surgeons should contact the Laminitis Clinic (0870-444-0676) and we can facilitate the granting of an STA for them.

 

***Update 2003 The Laminitis Foundation no longer endorses Founderguard

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It must be remembered that excess carbohydrate is not the only cause of laminitis. One of the increasingly common causes is that of Cushing's Disease secondary to a tumour of the pituitary gland. These cases are becoming more generally recognised these days and there are effective "treatments" which can give the horse or pony many good years of life. However, we are starting to recognise cases which have the same clinical appearance as the pituitary tumour cases, i.e. failure to shed their coat, increased thirst and appetite yet loss of bodyweight, swellings above the eyes, and laminitis; yet these cases do not have pituitary tumours. They are due to an abnormal activation of a cortisol enzyme system. Unfortunately these cases are not simple to diagnose and as yet we have no effective treatment for them. They are referred to as Peripheral Cushing's Disease and I suspect that many of these were previously diagnosed as pituitary tumour cases.

On the positive side, there have been some interesting developments in laminitis research lately. Firstly research has shown that there are two types of bacteria which are released in the horse's hindgut following over-consumption of food rich in soluble carbohydrate e.g. grass or cereals. We know that there is a massive switch in the bacterial population of the hindgut in these circumstances. As carbohydrate is not normally present in the hindgut in large quantity, bacteria which can live on it multiply rapidly following its entry. Their population numbers double every 12 minutes! These bacteria are gram positive cocci and they all produce lactic acid as a by-product of their growth. This lactic acid not only makes the gut contents acid, the acid damages the gut lining which enables toxins to be absorbed into the blood stream. In addition these bacteria release an exotoxin from the outer lining of their cell bodies which has an extraordinary effect on the laminae in the horse's foot.

There are a group of enzymes in the laminae called MMP's. Their normal function is to allow growth of the hoof down the foot by attaching and detaching the hoof capsule from the underlying laminae. The exotoxins from the bacteria in the gut cause a mass activation of these enzymes which appears to cause the hoof to detach from the horse.

 

In addition to producing lactic acid and exotoxins the rapid growth of the gram positive bacteria causes the mass death of the normal bacterial inhabitants of the hindgut which cannot live in the new conditions of acidity. When these die they release another sort of toxin, an endotoxin, from the inner lining of their cell bodies. We have known about the endotoxins for a long time and early researchers thought that these were the mechanism of dietary laminitis. Current knowledge denies this. Endotoxins have a variety of very unpleasant and often lethal effects on a horse but they don't cause laminitis.

 

copyright © Robert A Eustace

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To keep up to date with the latest Laminitis research please view the
Laminitis Trust's website

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My book "Explaining Laminitis and its Prevention" provides much more information than I can give here. It is available from good equestrian suppliers, by Mail Order from the Laminitis Clinic on 0870-444-0676, via the Laminitis Trust website or from the links provided below.

 

Explaining Laminitis and Its Prevention by Robert A Eustace, UK Laminitis Trust

This book is currently out of print.  Dr Eustace will be writing an updated book.

 

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Finally, the Laminitis Trust has two research projects in the planning stages but both require substantial funding. If any of you would like to help us by displaying a Laminitis Trust collecting box or organising fund raising activities we would be very grateful.

 

 

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