What is laminitis?
Laminitis is a disorder that is associated with overfeeding sugar or water-soluble carbohydrates. It is not a disease, rather the result of several conditions. It is very specific; an inflammation and, ultimately, breakdown of the lamellar which is connective tissue that holds the hoof to the bone of the toe. There are three phases of laminitis; developmental, acute and then long term, chronic phase. Within these are levels of intensity.
What causes laminitis?
The cause, or causes of laminitis are both complex and inter-related. The actual physiology of laminitis at hoof level involves poor circulation, vasoconstriction (narrowing of blood vessels) and pooling of toxins (from disrupted hindgut fermentation), pro-inflammatory factors, oxygen starvation and the inability of glucose to energise normal hoof metabolism.
Simply, where blood pressure is at its weakest (the hooves are the furthest point from the heart) there is limited ability to flush away negative factors, to replace vital oxygen and supply the area with its energy needs. Couple this with inflammatory factors that further restrict circulation, inflammatory factors that are released due to oxidative damage, and the release of MMP (metalloproteinase) due to poor circulation, the end result tends to be laminitis. It is one of the reasons that gentle walking for the horse can help – merely by improving blood circulation.
What does this look like visually?
The following diagram illustrates various interactions between potential causes, routes of action, and effect. The major instigators of these factors are endocrinological. This includes obesity, insulin resistance PPID, dietary (e.g. too many fructans, sugars, overeating) or mechanical (bruising, wounds). Finally, breed is a factor, with native breeds being most susceptible. Individually, these causative factors may not trigger laminitis, or just give mild symptoms. However, a combination of different aspects can increase the risk and severity. For example, an obese horse on a high starch diet will be more susceptible to a laminitis than a lean animal on a high forage diet. And in physical terms, a heavily obese horse, with hoof damage can exhibit laminitis where a lighter horse would not. This means that there will be some horses that are more prone to laminitis than others and will succumb due to an additional factor beyond endocrinological factors, breed etc
How can diet impact laminitis?
In addition, causes can be dietary, the most infamous factor being spring grass.
A wild horse, coming out of a winter of limited grazing and loss of condition, undergoes some hormonal changes to adapt the rich new growth. For the domesticated horse, well fed over winter and grazing on high quality grass, there is likely to be nutritional overload as a result.
Spring, with its surge in growth is accompanied by increases in protein, sugars and fructans. In the case of diet; mineral imbalance or individual overages or deficiencies can trigger an effect. However, the best-known “culprit” is probably the feeding of excess non-structural carbohydrates, such as sugars, starch or fructans.
Why then are non-structural carbohydrates particularly implicated whilst structural ones (fibres) are not? The answer is relatively simple. It depends on the microbes in the gut.
Fibre cannot be digested, but can be microbially fermented – mainly in the hindgut – and the end products (organic acids, nitrogen compounds etc.) can be absorbed and utilised by the horse.
The carbohydrate end products are mainly acetate, propionate, butyrate (VFAs) and lactate, and of these lactate build-ups are strongly implicated in laminitis. However, fibre fermentation is a slow process and in the case of the horse much fibre is voided before it is fully fermented.
However, when feeding too much sugar, the horse’s enzymes can only breakdown a limited amount and there is a dumping of carbohydrate in the hindgut. Fermentation of this carbohydrate encourages less specialised bacteria which produce not only high levels of lactate, but also kill those microbes that can ferment fibre. Changes in fermentation patterns encourage more growth from the lactate producers, which rapidly break down fructans, leading to the absorption of endotoxins, pro-inflammatory and vaso-constrictive factors that contribute to the onset of laminitis.
Many modern grasses have been selectively bred to enhance their protein and carbohydrate content – great for the high yielding dairy cow, less so for horses. Natural meadow grasses, or better yet moorland grass, have slower growth, lower nutrient levels and so are “safer” for those horses prone to laminitis. However, the best solution is to limit the amount of spring grass; turning out onto short, cropped grass may not be the best policy as the sugar component of carbohydrate is stored at the base of plant, prior to mobilisation for growth. It is therefore better to reduce grazing time to early in the morning where the horse can graze the leaf tips, before sugar mobilisation.
Hay is an alternative – usually fed all year round to those particularly sensitive, but soaking for lengthy periods is required to remove sugars.
A third way is the provision of low sugar/starch/fructans fibre sources. Beet pulp products can be extremely low in sugar, with reasonable protein levels and a fermentation pattern that is very low in lactate – all the factors that don’t exacerbate laminitic tendencies. Feeding these products, such as Speedi-Beet & Fibre-Beet can reduce overall intake of those “at risk” nutrient levels. For example, as horses tend to have a greater rate of feed intake in the morning (diurnal behaviour patterns), a well soaked portion of Speedi-Beet before turnout will help reduce intake of spring grass. A few mounds of these products, spread across the field will fulfil behavioural seeking/foraging behaviours and limit grass intake.
Both Speedi-Beet and Fibre-Beet are suitable for horses and ponies prone to laminitis. Speedi-Beet is 5% sugar and 0% starch, Fibre-Beet has 3% starch.
If you are concerned about your horse or pony being overweight, you can confidently feed Speedi-Beet as it helps the mobility of the gut, offsets the sugars in the grass when fed before turn out and contributes to the essential digestible fibre part of the horses or ponies diet. Not only that, as Speedi-Beet is a soaked product, it expands to five times the size, meaning it can be fed as a low calorie, digestible fibre.