The death of Jimmy, the $5 million half-brother to Black Caviar, thrust laminitis into the spotlight. Here, in the first of a two-part series, we discuss the nature of the disease and different ways it can be treated. Be aware that laminitis can occur suddenly and develop into a serious illness quickly. We hope this series helps you by providing the clues to early recognition, the key to beating this awful disease.

 

 

Dr David T. Wood, BVSc, MRCVS, is a Perth veterinary surgeon with 35 years equine experience in several countries. For the past 20 years he has pursued a special interest in equine nutrition and currently acts as veterinary and technical advisor to Horsepower.

 

What is laminitis? As the name suggests, laminitis is an inflammation of the sensitive laminae of the foot -- the soft tissue structures that attach the pedal or coffin bone of the foot to the hoof wall. Laminitis is like one of those terrible anti-personnel mines that aim to cripple rather than kill their victims, though many afflicted horses will eventually be euthanised because of it. Like a land mine, it can strike without warning and with disastrous results. One of the many problems with this disease is that by the time the signs of inflammation, swelling pain and increased blood flow show themselves, the damage to the delicate laminar membranes may already be severe, limiting the possibility of effective treatment. 

 

Early recognition of the signs is critical in determining the outcome, though we now know the disease may progress without obvious signs well before showing itself. The laminitic horse shows some or all of these signs:

 

By the time these signs develop, structural damage to the foot may have already happened. Veterinary help should be sought urgently – far better a false alarm than a crippled horse. Veterinarians may use the Obel system to grade the severity of the laminitis-related pain and help determine treatment options. The system uses four categories:

 

A history is also taken and a clinical examination made to identify any underlying causes for the attack with a view to eliminating them if possible. The main diagnostic tool used here is radiography. This enables the vet to determine whether the coffin bone has separated from the hoof wall and rotated, and if so, the degree of rotation, an important predictor of prognosis. In mild cases there may be little or none. In the severest cases, the coffin bone may sink right into the sole of the foot and penetrate it with dire consequences for the horse. Typically, the front feet are more affected than the hind due to the uneven weight distribution of the horse’s body, with around 65 per cent of its weight borne in front. All feet may be affected, however.

 

At the heart of underlying causes is a degradation of the "basement membrane'', the surface of attachment between the sensitive and insensitive laminae of the hoof. These sensitive laminae attach to the horny insensitive laminae inside the hoof like interlocking leaves holding the hoof wall and sole onto the underlying structures of the foot. This specialised cell layer covers the gap between the two sorts of laminae, which under a microscope resembles Velcro. 

 

Broadly speaking, we can distinguish two main causal types – inflammatory and hormonal. Inflammatory causes include carbohydrate overload, generally involving excess starch from grains or fructan (a polysaccharide) found in pastures, or both, causing a change in the balance of micro flora in the large intestine. It is thought the resulting increase in acid can damage the intestinal lining, allowing bacterial toxins to leak into the circulation and become implicated in causing laminitis, either alone or in conjunction with fructan. Sepsis, an infection of another organ such as the lungs (pneumonia), bowel or uterus, especially post foaling, can provide a source of bacterial toxins entering the bloodstream with similar results.

 

As for hormonal causes, in the past few years it has been shown that high blood insulin levels can cause laminitis. Insulin-resistant horses are predisposed, as are those with equine metabolic syndrome and Cushing's syndrome. It seems this has a direct effect on the lamellar tissues in the hoof, independent of inflammatory causes. What seems clear is that insulin-resistant horses are more susceptible to laminitis resulting from fructan overload from pasture. The insulin resistance reduces their ability to control blood sugar levels and results in a high resting insulin level. When challenged by high fructan loads, the already high blood insulin spikes further and laminitis may result.

 

Laminitis has also been associated with direct trauma to the foot, for example, from excessive hard road work (road founder), over-trimming of the sole of the foot, hoof infections and swelling of the legs. One specific type is called contra lateral limb laminitis, where pain and lameness in one leg – from a fracture, for instance – results in excessive weight being borne on the matching leg on the opposite side, eventually resulting in a type of inflammatory laminitis.

 

 

 

Andrew Bowe, BAppSc, is known as The Barefoot Blacksmith, a master farrier specialising in the barefoot rehabilitation of horses with acute or chronic lameness. His business is based at his property, Mayfield, near Yarck, in central Victoria. Visit www.barehoofcare.com. For more information on Professor Robert Bowker, visit www.coronavistaequinecenter.com.

 

 

Fortunately, over the last decade, a more complete understanding of the physiological processes underpinning both healthy and pathological hooves has evolved, enabling a paradigmatic shift in how we can manage laminitis. No longer is there such a poor prognosis. As a result of this information, many laminitic patients that would otherwise have been euthanased without question are being routinely saved, often getting back under saddle, business as usual. 

 

 

 

 

 

These developments have been made possible by the research of Professor Robert Bowker from Michigan State University, who found that optimal blood flow through hooves occurs only when they are supported fully by all the ground surface structures of the hoof, especially the frog and sole. The wider the load is spread, the better the blood flow. Quite significantly, he also found that the hoof wall should only be weight-bearing on its inner rim, whilst the outer rim of hoof wall actually needs to be non-weight-bearing.

 

This discovery directly contradicts the long-held belief that hooves are meant to bear weight on the walls alone and thus brings the realisation that there is an underlying contraindication with any shoeing for laminitic hooves because it weights the wall and therefore the laminar bond. But herein lays political sensitivity, so this new information has not yet been widely embraced by those trained in the traditional hoof-care paradigm. Hopefully this will change as anecdotal evidence supporting Professor Bowker’s theory continues to mount. 

 

Meanwhile, in situations of such conflicted opinion, it is wise to stand back and look at the whole dynamic picture. Laminitis can be viewed simply as inflammation within the laminar bond; the Velcro like structure that attaches and aligns hoof capsule to bone. In a laminitic hoof, the Velcro is effectively getting torn apart, and for it to re-attach completely and correctly, all contradictory mechanical forces need to be removed from the equation.

 

The other significant evolution for laminitis management concurrent to Bowker’s research has been the advent of plastic rubber hoof boots that can be easily put on or off. When used with very soft rubber foam padding, they can give horses great comfort and support for sore hooves, far better than any therapeutic shoe ever could.

 

Even though the disease quite obviously manifests in the hooves, which are at the front line of battle, it is important to recognise that hooves are symptomatic, not causative. The actual war is won by finding and removing the underlying cause. This is why it’s so important to seek veterinary assistance from the outset, so as to get good diagnostics. A vet is also needed to take Xrays (radiographs) to determine the position and health of the pedal bones (make sure any shoes are taken off prior so the tip of the pedal bone is not hidden from view and the point of the frog is marked by a drawing pin).

 

The hooves should then be trimmed as soon as possible in order to remove the tearing force off the laminar bond. This means removing all weight-bearing from the hoof wall from heel platform around to heel platform with the rasp held at about 45 degrees to the solar surface. The sole in front of the pedal bone needs also to be relieved of weight-bearing (hence the need for well-marked radiographs to gain an external reference point for the pedal bone).

 

 

 

Comfort and support are then provided straight away by putting on boots containing soft rubber pads. This spreads the weight-bearing load as widely as possible, thus restoring blood flow. 

 

 

 

A great feature of hoof boots is that they can be continually adjusted to maximise comfort and support. If necessary, wedges can be added to release tension from the flexor tendon and extra frog support can be added to decrease pressure on overly sensitive solar areas. 

 

Full laminar recovery is then facilitated by constant trimming of the hoof walls to keep them from weight-bearing. To this end, trimming should be on an as-needs basis, even once a week during the first few months of recovery. Hoof walls can grow amazingly fast when hooves are subjected to cellular inflammation.

 

 

Normal trimming parameters are gradually restored as the new hoof grows down and it can resume its normal function of sharing the weight-bearing.

 

Laminitis is a pathological condition of a horse’s whole system, so recovery is aided by introducing a temporary emergency diet. The patient needs to be immediately taken off grass and it needs to be fed a diet in which sugar removal is the initial focus. 

 

 

Not all horses that suffer serious laminitis can be saved, but the author has been employing the principles of barefoot rehab as outlined here for well over a decade; long enough to know which management factors can greatly influence prognosis. The deck of cards can be stacked favourably.

 

Don’t dismiss as unimportant what initially appears to be just a mild case of laminitis. It is impossible to tell the difference between mild and serious at the beginning. You may well be looking at just the tip of a very big laminitic iceberg.

 

Don’t delay the commencement of rehabilitation. Living cells in the hooves are being starved of blood and are dying. The window of opportunity for full recovery closes in days, not weeks.

 

Don’t force a laminitic patient to move. Let them move if they want to, but don’t force them. Pain is there to alert the horse to serious damage. In fact, it is best to keep a convalescing patient in an environment that it feels secure enough to lay down in, ideally an airy open-sided shelter with other horses nearby. Lying down is the best way to get pressure off laminitic hooves.

 

Don’t try and maintain a laminitic patient in show condition. A horse that is recovering from a laminitic episode will likely lose weight. Looks are definitely not the priority. Sore hooves are far better off to be carrying less body weight. They can and will put weight back on later. 

 

Don’t drop your guard part way through the recovery process. There is constant, taxing work involved with laminitis rehab, but just because a patient is steadily recovering, doesn’t mean the journey is over. The whole hoof capsule needs to grow out for full soundness and strength of laminar bond to return. Think Velcro. The smaller the surface area of Velcro connection, the weaker it is. 

 

It is vital that recovering patients are not let out onto grass too soon, or don’t have their padded boots taken off and get turned out barefoot or not are ridden too soon. Frustrating as it may be, it really is a case of hurry up and wait. It is best to follow the advice of the trimmer who is managing the hooves before making any such changes.

 

Be aware of medications that may be affecting recovery. There may also be some (anecdotal) links between medication and failure to heal (such as long-term use of phenyl butazone) or osteoporosis (from the long term use of pergolide). Alternative medications/herbal treatments may need to be introduced. Again, your trimmer will be able to advise you how well the hooves are recovering. 

 

Part II of this story can be viewed here: http://www.equestrianlife.com.au/articles/Laminitis-Living-with-the-aftermath