Laminitis is one of the most common causes of lameness in horses and ponies. It is a painful and potentially fatal disease that affects the hoof of the animal, but in cases of dietary-induced laminitis, it is believed that the physiological changes that trigger it, actually originate from the gut. There are several types of laminitis – Cushingoid, toxaemia (ie. from retained placenta), metabolic and concussive. However, dietary laminitis is the most frequently observed form of the disease.
Dietary laminitis can affect all types of horses and ponies at any time of the year, however, seasonal changes in the grass can have an effect. Dietary laminitis is thought to occur due to inappropriate breakdown of soluble carbohydrates (sugar and starch). To understand this fully it is important to remember that horses are grazing animals and have evolved to eat high fibre, low energy diets. They trickle feed throughout the day – that is, they eat little and often, for several hours at a time, rather than eating in meals. Their digestive system has not been designed to cope with large, calorie-dense buckets of food.
The horse’s digestive system starts with a small stomach, about the size of a rugby ball, that should never be filled by more than two thirds. As horses cannot vomit, the digestive system has an in-built safety feature that will prevent the horse’s stomach from rupturing if it becomes too full. This safety feature will cause the stomach to empty into the small intestine, when it nears capacity. This is good at preventing damage to the stomach, however, it is not so good for the digestive process, as early emptying means that the food starts to pass into the rest of the gut before it is ready. The food will then pass into the small intestine (a long narrow tube) where food moves through at a constant rate. If a lot of food is fed, then the squeezing movements of the gut (known as peristalsis), push the food through the small intestine very quickly. This can lead to the food not being digested fully by the enzymes that are secreted into the small intestine, meaning that starch and some sugars (fructans) can be pushed undigested into the large intestine.
There are millions and millions of bacteria that reside in the hind gut, all of which work to break down fibre through a process of fermentation. If starch enters this area, then the bacteria prefer to break down this, rather than the fibre. Similarly, if fructans (storage carbohydrates found in grass) are consumed, they cannot be broken down in the small intestine, so pass into the hind gut, where again, bacteria rapidly ferment them. When the bacteria ferment the starch and fructans, they produce an acid, called lactic acid, as a by-product. Unfortunately, there are not many bacteria which can live in lactic acid and so many die off. It is thought that this acidic environment can also damage the gut wall, which in turn, allows some of the dead bacteria and other molecules (often termed “endotoxins”) to enter the circulatory system. It is believed that these endotoxins can then cause inflammation of the blood vessels which can lead to laminitis.
Laminitis tends to affect both front feet although it can affect any, or all feet at any one time.
LAMINITIS SHOULD BE TREATED AS A VETERINARY EMERGENCY.
If you observe any of the following signs of acute laminitis, call your vet immediately:
• Your horse is lame and reluctant to move, making only small, careful, ‘pottery’ strides. This may be more noticeable on a turn or on hard surfaces.
• Your horse may look as if he is putting his heel to the ground before his toe when he is walking.
• The ‘laminitic stance’ is characteristic of the condition, with the forelegs stretched forwards and weight shifted onto the heels to relieve pressure from the toes.
• Your horse may appear uncomfortable, shifting weight from one foot to another.
• In severe cases, your horse may become recumbent (lying down).
• Your horse’s coronary band may be unusually warm, but this is an unreliable sign.
• You can feel a pounding digital pulse in the pastern.
• Your horse’s sole is abnormally sensitive to pressure.
• Putting him in a stable on deep shavings, paper or sand bedding – try to avoid straw as your horse may eat it.
• Removing feed and hay, but not water.
• Allowing him to lie down if wanted.
When plants photosynthesise, their leaves absorb carbon dioxide and sunlight which are used to produce sugar. The sugar can be used to fuel growth, or be made into storage carbohydrates known as fructans, for later use. Many plants, such as cereals, store their energy as starch, but grasses store excess carbohydrates as fructan. When grass is using a lot of energy for rapid growth or flower development, the carbohydrates stored in the plant will be fully utilised, so the amount of fructans within the plant will decrease.
Conversely, when growth is reduced, but photosynthesis continues, fructan levels will increase.
1. Ensure your horse is a healthy weight as obese horses are at greater risk of developing the disease.
2. Limit the soluble sugars your horse consumes: molasses, cereals and lush grass can all be high in either sugar or starch.
3. Restrict grazing by either strip grazing your pasture or placing a grazing muzzle on your horse.
4. Avoid turnout on days when it is very cold but very bright and sunny as the fructan concentration will be at its highest. Wait until the temperature has risen and any frost on the grass has melted.
5. Ensure you feed a high fibre, low sugar, low starch diet. Feeds such as Fast Fibre and ‘L’ Mix are ideal.
6. Avoid high energy forages such as haylage, alfalfa and red clover. It may be an idea to soak your hay also, as this will remove any soluble sugars that remain in the forage from the harvesting process.
Careful feeding is an important part of the management of horses or ponies prone to laminitis. A high fibre, low starch and low sugar diet is essential, so avoid feeds that contain cereals or molasses. Both Fast Fibre and 'L' Mix are designed specifically for horses and ponies prone to laminitis and are high in fibre and very low in starch and sugar, each with a combined level of well under 10%. Fast Fibre and 'L' Mix are both completely free from added sugars, so do not contain molasses or anything similar - check your feed labels to be sure that this is the case with anything else you are feeding. With no added cereals, sugars or molasses, 'L' Mix is also very low in calories, containing less calories than the equivalent amount of chaff, so is the perfect choice for a very low energy diet. Fast Fibre has a slightly higher calorie content, so is perfect for horses and ponies that require a little more energy. ‘L’ Mix includes long fibre which will increase the time spent chewing, helping to keep your horse or pony occupied if he has to be stabled. Fast Fibre is the quick soak fibre provider and is ideal for horses and ponies with poor dentition. 'L' Mix also includes probiotics – a yeast supplement designed to help maintain a healthy balance of microflora within the digestive system, probiotics also act as a rich natural source of vitamins and minerals. A unique blend of human food grade herbs is specifically targeted to nutritionally support healthy hooves and in particular, the laminae, as well as supporting healthy digestive and circulatory systems.
If your horse is overweight, reduce his feed and change to a low calorie, high fibre feed such as 'L' Mix. Do not starve your horse as this can lead to other problems. He should still receive a total of 1.5% of his bodyweight in feed each day. Don't let your horse or pony get overweight in the first place by keeping a close eye on his condition. You should be able to feel his ribs easily when you run your hand lightly across his ribcage, but not see them. He should have no fat deposits, particularly on his crest.
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