LAMINITIS. Severe bruising just in front of the point of frog where there is pressure from the rotating pedal bone

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1 WHAT IS LAMINITIS? LAMINITIS The inside of the hoof is arranged in layers called laminae which interdigitate and suspend the pedal bone in a stable position within the hoof wall. Laminitis occurs when the laminae become inflamed and the complex attachments within the hoof begin to fail. It is a very painful condition and in severe cases when the attachments fail completely the pedal bone rotates and sinks within the hoof. The sole in front of the point of the frog might become soft and bulge outwards under pressure from the pedal bone and in worse cases the bone might penetrate through the sole. Severe bruising just in front of the point of frog where there is pressure from the rotating pedal bone WHAT ARE THE SYMPTOMS OF LAMINITIS? Laminitis can be described as 'acute' whereby the symptoms tend to occur suddenly or 'chronic' whereby the symptoms appear gradually and remain over a prolonged period of time. Acute laminitis: symptoms occur suddenly and severity may range from mild to severe most commonly occurs in both forelimbs but hind limbs or just one limb can also be affected short pottery gait with heel first foot ground contact warm feet and coronary band increased pulse at the level of the fetlock and pastern signs are potentially reversible with no permanent changes within the hoof Chronic laminitis: occurs following an acute attack of sufficient severity or duration to result in permanent structural changes to the foot eg rotation or sinking of the pedal bone or 'Aladdin's slipper' elongation at the toe of the pedal bone divergent rings in the hoof wall widening of the white line, predisposing to abscesses solar bruising

2 Divergent growth rings as seen in chronic laminitis WHAT CAUSES LAMINITIS? Traditionally it was believed that laminitis resulted from a disruption of blood flow to the hoof. We now know that laminitis is a complex disease caused by a variety of factors including the triggering of enzymes which break down the attachments within the hoof wall and changes to the blood supply to the foot. In addition, it has been found that the cells within the hoof require glucose to maintain their attachments so it is thought that disruption to glucose metabolism might also predispose to laminitis. There are several conditions and predisposing factors that can lead to laminiits: Obesity Overload of carbohydrate feed eg a pony breaking into the feed room and gorging on concentrates Eating grass high in soluble carbohydrates eg in the spring and autumn or after a frost Overloading the feet eg heavy exercise on very hard surfaces or overload of one foot due to a severe lameness in another Severe infection or illness eg colic or retained placenta after foaling Use of steroids (rare) Metabolic disease eg Cushings disease or Equine Metabolic Syndrome Native ponies seem particularly predisposed to laminitis, probably because they are adapted to live on poor upland grazing where they would naturally lose weight over the harsh winter months. WHAT IS CUSHINGS DISEASE? Cushing's disease is most common in older horses and occurs due to overproduction of the hormone ACTH. This results in high levels of the steroid hormone cortisol which causes various problems including increased drinking and urination and susceptibility to infections and laminitis. It can be treated with the drug pergolide which helps to reduce the production of ACTH. For more information on Cushings Disease and its treatment see

3 WHAT IS EQUINE METABOLIC SYNDROME? EMS occurs in horses which are resistant to insulin, meaning the body must produce high levels of insulin in order to work effectively. This usually occurs in overweight horses or those with abnormal fat deposition. For various reasons insulin resistance can predispose to laminitis. EMS can be controlled by the drug metformin in conjunction with weight loss, careful dietary control and exercise. HOW IS LAMINITIS TREATED? An obese pony with EMS Laminitis, particularly in the acute phase, is a medical emergency and you should consult your vet as soon as possible. There are 3 priorities in the treatment of laminitis: 1. Stabilisation of the structures within the hoof 2. Relief of pain 3. Treatment of the underlying cause Stabilisation of the structures within the hoof This is achieved by minimising the forces acting to break down the failing attachments within the hoof. Movement should be minimised by placing the horse on box rest. Providing a deep bed is often recommended as it makes the horse more comfortable and will help to spread the weight of the horse over the whole surface of the hoof rather than just the walls. Shavings, peat or sand are most effective. Straw is not recommended as it will often be eaten by a hungry horse or pony and diet is an important part of treatment (see below). Your vet may also recommend the use of a hoof support material (eg Newmarket Sole Support) which is usually bandaged and taped in place over the foot to provide support.

4 Relief of pain The most commonly used drug in the control of pain in laminitis is phenylbutazone (bute), but your vet will decide on the most appropriate drug and dosage for each individual case. Drugs such as phenylbutazone (bute) also have an anti-inflammatory effect which can be beneficial. Treatment of the underlying cause This will obviously depend on the cause, for example: Avoidance of grass high in fructans and high carbohydrate feeds (see below for advice on feeding). Fluids and antibiotics in the case of infection and toxaemia Administration of liquid paraffin or activated charcoal by stomach tube to speed up the passage of food through the digestive tract or to absorb ingested toxins Treatment of Cushings disease or Equine Metabolic Syndrome. If the vet suspects undiagnosed equine metabolic syndrome or Cushing's disease he or she might suggest taking blood samples to test for resting ACTH, glucose and insulin. Other treatments that may be used: The drug Acepromazine, ACP (Sedalin Gel) may be advised by your vet. This drug is actually a mild sedative but has a side effect of vasodilation which is thought to help blood flow to the laminae. The sedative effect can also be useful if the horse or pony is anxious about being on box rest. If equine metabolic syndrome is diagnosed your vet may advise treatment with metformin. If Cushing s disease is diagnosed your vet may advise treatment with pergolide. Your vet may also advise an anti-oxidant supplement which may help combat the inflammation within the hoof. A hoof supplement may also be recommended to promote healthy foot growth. Further advice on feeding: All cases need to be fed a restricted diet as part of the treatment of laminitis. This means reducing the intake of soluble carbohydrates such as in grass (ie fructans) or high carbohydrate feeds. Whilst on box rest and receiving treatment for laminitis, the following is a good guide to feeding 1. Do not feed any concentrates (ie cereals, mixes, nuts etc) 2. Avoid treats such as polos and even carrots and apples too as they are surprising high in sugars 3. No grass 4. Feed high fibre feed ie roughage only. The recommend amount is 1-2% of bodyweight (as drymatter). This can be achieved by feeding hay, alfalfa, Lucerne or even straw. Feed as poor quality hay as possible but avoid mouldy or dusty hay. Care must be taken with feeding large amounts of straw as it may be more likely to cause impactive colic. In theory haylage may have fewer sugars than hay as some have been fermented in its production. In reality many

5 batches of haylage are actually rich in sugars so if feeding haylage be cautious and it may be best to opt for one produced especially for laminitics. A simple guide would be as follows: Horse- approx 500kgs. Pony- approx 300kgs Shetland pony- approx 150kgs Approx 3 slices of hay (about 6 kgs) + 2 x 1kg scoop hi-fi* Approx 2 slices of hay (about 4 kgs) + 2 x half scoop (0.5kg) hi-fi* Approx 1 slice hay (about 2 kgs) + 2 x handful (total 0.5kg) hi-fi* Hi-fi* can be any kind of unmolassed chop/chaff/hifi/alfalfa. The Hi-fi component could be cut out and replaced with hay instead but it is usually required in order to give oral drugs and supplements. Your vet will advise how long this restricted regime is necessary for. Obese animals will need prolonged restriction in order to lose weight and prevent further episodes of laminitis. Animals that have suffered from laminitis will be very prone to suffering from the condition again and therefore it is advisable to keep them permanently on a diet which is low in sugars by avoiding starchy concentrate feeds and restricting grazing. Xrays and farriery Each individual case is different, but the vet might also take X-rays of the feet to assess the position of the pedal bone. This provides useful information regarding the severity of the laminitis and is also useful for farriers when they are deciding on the most appropriate way in which to trim the feet. Remedial shoeing may be required in order to provide ongoing support for the feet. Your vet will liase with you and your farrier to discuss the options available. Prompt and aggressive treatment of laminitis is extremely important and many cases do very well with such treatment and good ongoing management. In severe cases there may be extensive, irreversible damage to the hooves. In such cases where this occurs and the horse will never be free of pain then the only option is euthanasia.