Laminitis is the second biggest killer of horses in the UK (the first being colic). It is traditionally associated with fat ponies grazing on lush grass, but laminitis can affect any horse and isn't just caused by horses eating rich grass. Horse owners need to know what symptoms to look out for and how they can prevent their horse or pony from developing laminitis.

What is Laminitis?

Laminitis is a metabolic condition which affects the whole of the horse's body but is most apparent in the feet due to inflammation of the laminae which lie between the hoof and the bone of the foot (pedal bone).

What Causes Laminitis?

Nutritional Cause:
Suddenly overloading the digestive tract with rapidly fermentable carbohydrates:

• Starch – in cereals and plants
• Sugars – in lush grass
• Fructans – in lush grass

Don't assume that if the grass isn't long your horse isn't at risk, short grass can still be sweet and lush and the horse could be eating it as fast as it grows. Overweight ponies are particularly at risk to grass–induced laminitis.

Other Causes of Laminitis:

• Any condition that leads to toxaemia or septicaemia such as:
• Retention of foetal membranes after foaling
• Excessive trauma to the feet – through excessive trotting on roads, jumping on hard ground
• Incorrect foot trimming over a long period of time
• Stress through travelling etc.
• Some drugs – e.g. Corticosteroids
• Excessive weight bearing on a limb

The Science Bit:

Endotoxins form - the sudden increase in carbohydrates causes a flush of lactic acid-producing bacteria, which kill the normal bacteria in the large intestine. This damages the mucosal lining which allows endotoxins from the dead bacteria and the lactic acid to enter the vascular system. Therefore any condition which generates endotoxins can lead to laminitis.

Bloodflow to the foot – blood pressure increases due to the endotoxins, which causes the blood to bypass the lower parts of the foot. This stops the laminae getting any oxygen and essential amino acids, causing the laminae to degenerate.

Pedal bone rotates – the blood and serum collect between the hoof and bone, causing them to separate. This takes away the support for the pedal bone, which causes it to rotate, pointing downwards and pressing on the sole.

Symptoms of Laminitis

• Lameness
• Reluctance to move
• Rocking back on the heels (acute laminitis)

Does your horse have Acute or Chronic Laminitis?

Acute Laminitis

• Severe pain in the feet, horse distressed, sweating and trembling.
• Fast pulse can be felt in the arteries underneath the fetlock.
• Front feet tend to be more sever than the back, so the horse stands with the hind legs underneath the body and the front legs extended in an attempt to alleviate pressure in the front feet.

Chronic Laminitis

• Horse lifts one foot after the other
• The foot will feel cold while the coronary band is hot

Laminitis causes the pedal bone to rotate due to the bond between the hoof and the pedal bone separating. This then causes pressure on the soles as the tip of the rotated pedal bone applies pressure on the sole of the foot. The sole can then change from a concave shape to a flat surface.

Treating Laminitis

Laminitis causes irreversible damage within the first 12 hours - immediate treatment is essential.

• Liquid Paraffin – administered in large quantities to help prevent further absorption of endotoxins
• Phenylbutazone – to reduce the pain and increase the blood flow to the foot which will reduce inflammation.
• Acepromazine – a sedative which dilates the blood vessels in the foot
• Heart Bar Shoe – can be used to support the pedal bone
• Surgery – in severe cases the front wall of the hoof may be removed
• Stable Rest – horses with laminitis need to stand still or lie down as movement causes separation of the hoof from the bone. Stable rest is recommended on a bed which helps to support the soles of the feet, a mixture of peat and sand is recommended or wood chippings can be used.

Preventing Laminitis

Horse Feed / Diet:

• Maintain moderate weight – you should find out what the ideal weight is for your horse according to its age, breed and the level of activity. Your vet should help you with this or see links to information below. Use a weigh tape or weighbridge to regularly monitor any changes in your horse's weight. If your horse starts to gain weight you should consider changes to the diet such as restricting grazing and increasing exercise.
• Avoid Cereals – cereal based horse feeds such as coarse mix should be avoided. If your horse is only doing light work there should be no need for supplementary feed. If your horse is in harder work choose a fibre and oil based feed with low levels of sugar and starch.
• Choose the right feed – look for horse feeds which are approved by the Laminitis Trust. You can gradually introduce oil into the diet to provide extra energy, starch should be avoided.
• Fibre – you should aim to feed fibre to your horse at a quantity of 1 – 2% of its bodyweight.
• Choose mature hay over new hay which is richer
• Make any changes to the horse's diet gradual
• Feed sizes should be kept small, as a guide a 500kg horse should have no more than 5kg of feed per meal.
• Alfalfa – studies have show that adding alfalfa to the horse's diet may help maintain healthy digestive system for horses who consume high levels of starch.

Grazing:

• Try to find grazing which has been well managed
• Carbohydrates and fructan levels are at their highest in spring and autumn, restrict turnout time during these periods.
• Grazing muzzles can be used to restrict the volume of grass eaten by the horse.
• Turning your horse out with sheep is beneficial as they help to graze the pasture down
• Use electric fencing to strip-graze your horse, limiting the amount of grass they consume over a certain period
• Turn your horse out in a ménage or arena to restrict grazing
• Do not allow your horse to graze on recently cut pasture

Laminitis is a potential risk for every horse, pony and donkey and can be fatal. Horse owners therefore need to focus on reducing the risk of laminitis occurring, prevention is most definitely better than the cure where laminitis is concerned. Some of the websites below provide further information and advice for horse owners.

Further Information
The Laminitis Trust:
http://www.laminitis.org/∞
Useful information and a useful Laminitis poster to stick up in your yard (£5)

Horse Condition Body Scoring:
http://www.shady-acres.com/susan/conditionscore.shtml∞

Laminitis Advice:
http://www.laminitis-advice.co.uk/∞
You can obtain a free factsheet on laminitis and there are free veterinary helplines for horse owners.

Glossary:

Endotoxins – toxins associated with certain bacteria
Vascular System - also called the circulatory system, made up of the vessels that carry blood and lymph through the horse's body.

Source:
The Complete Equine Veterinary Manual, Tony Pavord & Marcy Pavord
Horse & Rider, May 2007

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