Laminitis

Possibly the most feared of equine disorders, laminitis is recognised in two basic forms that we will describe as “impact” and “toxic”. Laminitis is the inflammation of the “laminæ” that bind the oof capsule to the coffin bone. In mild cases it is just painful; in severe cases the capsule detaches from the coffin bone and rotates around the bone – often incorrectly described as “coffin bone rotation”. Laminitis can affect just the front hooves; it is usually more acute and/or severe forms that affect the rear hooves as well. Laminitis very rarely affects just the rear hooves.

Defining laminitis


Impact laminitis is as a result of overexposure to high impacts of the hoof and is essentially severe bruising resulting in inflammation.

Toxic laminitis, is in most cases a “luxury” illness; in general confined to horses that are considered “well looked after”, this form of laminitis all to frequently results from confinement and an unsuitable diet. In a few cases, it is the result of the horse being unintentionally exposed to an unsuitable diet (for example, the horse that escapes its field and ransacks the neighbour’s supply of chicken feed!).
Medicines can also trigger laminitis, the best known being certain anti-inflammatories (NSAIDs), often given in order to prevent laminitis. It should be noted that usually it is not the NSAID alone that is the cause but rather the combination with confinement that is often prescribed concurrently.
Another trigger can be pregnancy and birth. A mare in foal has a raised chance of developing laminitis due to the “foreign body” that she is carrying and its inherent toxins. If, after the birth, the placenta is not fully ejected, this too can cause a laminitic reaction. As with most other forms of toxic laminitis, the mare in foal is most at risk when confined and exposed to an unsuitable diet; on the other hand, the incomplete ejection of the placenta is a risk associated with birth.
Finally, PPID (Pituitary Pars Intermedia Dysfunction, formerly known as Cushing’s Disease) can also play a role in toxic laminitis; the horse becomes insulin resistant resulting in similar symptoms to the “sugar overload” seen in horses on an unsuitable diet. It is hypothetically probably that PPID falls into the category of “luxury illnesses”. The cause of PPID is quite probably dietary and is little more than an irreversible sugar overload later in life.

Defining definitions

There is often misunderstanding when describing the onset and severity of laminitis. There are three words that seem to cause a lot of confusion:
Acute : this simply describes the rapid onset of an illness (often within hours) and is no indication of severity.
Chronic : again, a time reference, chronic describes something long term or repetitive and is also not indicative of severity.
Severe : what it says on the packet…but not connected with the rapidity of onset nor length of illness. The opposite of severe is mild.

Identification


Laminitis can be difficult to indentify initially. If the onset is not acute, the horse may initially appear to be just slightly lame; however, this lameness will affect both hooves – rarely is lameness on just one side an indication of laminitis. This lameness will get progressively worse and the horse will start to adopt a stationary pose the avoids putting any pressure on the front feet.

Treatment


Laminitis is not easy to treat which is probably the reason why in the past so many horses were put down fairly soon after diagnosis. Even today, many horses are put down on the advice of the vet because the condition does not appear to be improving, or even at times, appears to worsen.
Even when caught early, laminitis can be very destructive of the hoof structures; clearly prevention is vastly preferable to cure. But it can be treated; but not in the way most veterinary specialists would propose these days. There is a very strong urge to confine the horse to a box, to restrict its movement, and to apply either egg-bar or inverted/reversed shoes to alleviate the effects of “coffin bone rotation”.
Since the horse is likely to be in too much discomfort for it to want to move any distance, confinement is both pointless and counterproductive. By isolating a horse in discomfort, one is adding to its problems psychologically. In addition, by confining the horse to a stable, its hooves are subjected to a degenerative environment of excreta and should perforation of the sole happen, this is most certainly the last place the horse should be. Furthermore, the toxins and the inflammation that are now present in the hoof need to be flushed which can only happen with good circulation; confining the horse severely restricts circulation.
The application of any sort of shoe displays a complete ignorance of the hoof, its mechanism and its function. Even for those practitioners who consider the coffin bone to be suspended inside the hoof capsule, it should be plainly obvious that the laminitic hoof, where the hoof capsule and the coffin bone are becoming separated, cannot in any way support the weight of the horse. And yet these people insist on applying “orthopædic” horseshoes (a nonsense term worthy of Lewis Carroll).

Thus, it should be clear that the initial way to proceed is to remove horseshoes, if they are present, and to turn the horse out.
However, it must be noted that the horse should not be turned out to rich pasture; if there is a high sugar content in the grass, then this will probably continue to affect to hoof and exacerbate the problem. Short, well cropped grass is a more viable alternative which ensures the horse has food but is encouraged to move to find it. Both movement and the small amount of food will be advantageous to the horse. Do not restrict the horse’s diet and do not feed commercial feed. Only grasses and hay.

Ensure that the hooves are trimmed such that the caudal structures (the “heels”) are lowered to a minimum – this is best done over a number of days rather than in one fell swoop – and the hoof wall is not carrying the weight of the horse. The latter is one of the major bones of contention with the traditional veterinary/farriery world; the hoof wall is not a weight bearing structure even in the healthy hoof so loading it when the hoof is unhealthy, and particularly when its connection with the underlying coffin bone is so weakened, is only going to worsen matters.

The horse must be kept under semi-permanent supervision to ensure it gets enough movement and the hooves must be trimmed frequently (as often as possible) to keep ahead of the damaging effects of the inflammation.

Recovery

This can be long and slow. Even with horses that have been caught in the early onset of laminitis, sufficient damage can have been done to complicate the healing process. In simple terms, the hoof wall must regrow to follow the line of the coffin bone (the hoof wall cannot “reattach” to the coffin bone, only new growth is attached). Generally this process takes up to a year (the length of time needed to grow a complete new hoof) but, depending upon the severity of the laminitic attack, it can be complicated by the formation of abscesses and by the rebuilding of the internal structures of the hoof which in turn can lead to deformations particularly of the sole. It is a process that can take more than two years before any real signs of recovery are evident.

Prevention


Obviously prevention is not so easily applicable to accidents – the horse escaping and devouring next-door’s grain store springs to mind. But in almost all other situations, it is quite possible to avoid – even impact laminitis. A shod hoof cannot absorb impact with the ground in the way that is intended and this can cause concussive impact damage. Asking an unshod horse to gallop over a stony or rocky path will similarly subject the hoof to abnormal stresses. The answer here is obviously never to shoe a horse and never ask the horse to do something it would not normally do.

Confinement in a stable reduces the horse’s movement and so also its use of sugars ingested. The majority of stabled horses are also fed a completly unsuitable diet – commercial feed with grain, cereals, molasses and other starches and sugars. This creates a sugar overload.
In early spring these horses, that have often been kept confined for the whole of the winter, are turned out to sugar rich pastures – pushing the sugar overload over the top… The answer here is firstly that horses should never be confined to stables – not even for a part of the day; secondly they should not be fed anything other than grasses and, at times of shortage, hay; thirdly, rye grasses and other high-production grasses should be avoided – these are particularly intended for cattle to increase both milk and meat production at the cost of their general health (laminitis is well known among cattle too); fourthly, horses should not be overfed during the winter months. insuling resistanceThis last point is always highly controvertial among horse owners; the general equine population, like its human counterpart, is overweight and for some reason, we seem to “prefer” our horses to be overweight. Most people, including animal welfare organizations, don’t know at what point a horse becomes overweight – the two body score indices in use, the various five-point scales and the Henneke nine-point scale both put the healthy horse too far up the scale! The reason for not overfeeding in winter is quite simple and very natural. This is how the horse has evolved and by reducing food intake during the winter, the insulin resistance cycle is broken. This cycle involves ingestion of sugars during the growing months whereby the sugar levels in the body increase; with the onset of winter, the amount of sugar ingested is significantly reduced allowing the body to “reset” and start all over again the following spring. The horse that continues to eat at the same rate during the winter does not get this essential reset and so, in the spring, the increased sugars just go piling on top of an already overloaded system.

Correct treatment of suspected laminitis will also go toward prevention; avoiding administration of NSAIDs, application of horseshoes or confinement are three very important factors sadly ignored by the mainstream veterinary profession.

The mare in foal should, as with any other horse, never be confined to a stable. She should be allowed to roam in as large a space as possible with her companion horses and not isolated as if she was ill. This in itself will be sufficient to greatly lower the chance of laminitis but to eliminate it more or less completely, the mare should not be fed commercial feed, just grasses and, when grasses are scarce, hay. She does not need feeding up with anything unnatural.

The incalculable risk moment for the mare in foal is post partum – if the placenta is not fully ejected this can cause a toxic reaction; it is therefore essential to check that the placenta is complete after the foal is born and if at all in doubt, call your vet out.