What is Acute Laminitis? Treating Acute Laminitis

Laminitis is one of the most complex disease syndromes facing the veterinarian and farrier. The disease is extremely complex and not well understood. And to compound the problem, the foot is actually a very poorly understood piece of the equine anatomy. The last couple decades have certainly changed the concept of "no foot - no horse" with the modern day horseman and professional. Advanced technology, current research and numerous articles concerning the foot have also fostered new concepts and ultimately a whole new mindset.

There have been tremendous advancements and increased knowledge about the syndrome; but unfortunately, even with all that is offered today in the prevention and treatment of the disease, little effort has been spent on classifying the degree of damage.

This may be defined as the period between the clinical onset of lameness and the stabilization of laminar degeneration/breakdown. It may be as short as 8 - 12 hours duration if the horse is exposed to black walnut shavings, or 30 - 40 hours in the case of carbohydrate overload.

Symptoms of the primary illness will be present along with lameness - usually in the front feet. On occasion, all four feet will be affected. When the forelimbs are affected, the horse will shift weight to the back legs, with the front legs extended. This is the typical "founder stance". In response to the pain associated with the condition, the horse may refuse to stand or walk. In the early stages, identifying the condition may require turning the horse in a circle, preferably on a hard surface. An affected horse's gait is typically short with rapid foot placement, hence the term "walking on eggshells".

At this stage, the digital pulse will be increased and the hoof will have an elevated temperature. There will be pain when the toe is compressed with hoof testers and there may be a depression of the skin proximal to the wall of the hoof, suggesting rotation or sinking of the distal phalanx.

At this stage, it is wise to X-ray the hoof, for baseline purposes, and to determine the position of the distal phalanx relative to the hoof capsule.

Acute laminitis occurs anywhere from 24 - 72 hours after the initial damage to the basement membrane and causes considerable pain. An affected horse may refuse to stand, and have increased breathing and pulse rates in response to pain.

What is Horse Laminitis?

Laminitis is a disease that horses get sore and inflamation of the the laminitic interface to the whole hoof capsule.

Laminitic Interface

The laminitic interface (stratum medium) is between 2 static structures, the hoof wall, known as "stratum externum", and the coffin bone face, known as the "3rd phalanx". So when the inflammation of the laminae (stratum internum) the pressure has no place to go except to compress the surrounding structures. This can be the circulation, the blood vessels, and other soft tissues of coronary band. The coronary cushion is part of the coronary band and this supports rotation of the hoof.

Laminitis Inflamation

In laminitis or acute lamanitis there is significant inflammation that builds up in and around the laminitic interface to the whole hoof capsule. This laminitic interface is sometimes called the "stratum medium". When there is inflamation in the laminitic interface it means the heel is just as inflammed as at the toe part of the hoof. However, the horse may rotate out the toes, known as the classic founder stance, to put more weight on the heel instead of the toe part of the hoof. So we make the assumption the there is more pain at the toe.

Stages of Laminitis

There are several stages to laminitis. These are defined as the periods between the clinical onset of lameness and the stabilization of laminar degeneration/breakdown. Onset may be as short as 8 to 12 hours duration if the horse is exposed to black walnut shavings, or 30-40 hours in the case of carbohydrate overload.

At this stage, the digital pulse will be increased and the hoof will have an elevated temperature. There will be pain when the toe is compressed with hoof testers and there may be a depression of the skin proximal to the wall of the hoof, suggesting rotation or sinking of the distal phalanx. If the hoof testers show pain at this stage, it is wise to X-ray the hoof, for baseline purposes, and to determine the position of the distal phalanx relative to the hoof capsule.

Acute laminitis occurs anywhere from 24 to 72 hours after the initial damage to the basement membrane and causes considerable pain. An affected horse may refuse to stand, and have increased breathing and pulse rates in response to pain.

Chronic Laminitis

Horses with chronic laminitis occurs when displacement of the distal phalanx has taken place but no active laminar necrosis is present. Horses with this condition are likely to get recurrent episodes of acute laminitis.

Sometime abnormal growth of the hoof may be present. When the dorsal laminae are affected, diverging rings may be noted around the hoof wall. These will be wider at the heel than the toe, indicating that growth at the toe is slower than the heel. The degree of lameness present depends on the use of the horse and quality of care.

Radiological changes at this stage will include improper alignment of the distal phalanx and hoof wall combined with the remodeling and osteolysis of the distal phalanx.

Laminitis as a Disease

Laminitis is one of the most complex disease syndromes facing the veterinarian and farrier of horses. The laminitis disease is extremely complex and not well understood by horse owners or the veterinarians that care for horses. To compound the problem of understanding the laminitis disease and how it can affect a horse, trying to understand the foot of a horse is just as important. We actually very poorly understood piece of the equine anatomy in general. For decades the concept of "no foot - no horse" has stood the test of time, and so we have provided images for you to look at the different parts to a horse's foot. When someone is more informed about the laminitic interface and how laminitis can inflam and stress the horse's hoof it becomes more clear that laminitis as a disease is best to be caught early and treated as an emergency to be addresses sooner rather than later.

Ultimately a whole new mindset needs to take place on what is best kind of treatment and care for a horse with laminitis. So please continue to read on how The Outlaw Pad provides aid and treatment to begin the healing process for horses with lamanitis or acute laminitis.

Chronic Laminitis

This occurs when displacement of the distal phalanx has taken place but no active laminar necrosis is present. Horses with this condition are likely to get recurrent episodes of acute laminitis.

Abnormal growth of the hoof may be present. When the dorsal laminae are affected, diverging rings may be noted around the hoof wall. These will be wider at the heel than the toe, indicating that growth at the toe is slower than the heel.

The degree of lameness present depends on the use of the horse and quality of care.

Radiological changes at this stage will include improper alignment of the distal phalanx and hoof wall combined with the remodeling and osteolysis of the distal phalanx.

Horses at risk for laminitis and founder

The following risk factors exist for laminitis and founder:

  • Horses on a high grain diet
  • Ponies
  • Heavy breeds, such as draft breeds (large body weight)
  • Overweight horses
  • Unrestricted grain intake (if the horse breaks into the feed area, for example)
  • Horses on lush pasture

Preventing laminitis and founder

Laminitis is a disease that is avoidable when proper horse management is practiced consistently.


Horse owners wishing to prevent the condition should observe the following:

  • Avoid feeding excesses and keep the horse at a reasonable weight.
  • Watch for and avoid grass blooms on pastures. Pull the horse off the fields and onto a dry lot if necessary. Feed hay in the morning and turn the horse out after dew has evaporated from the grass.
  • Keep grain in closed bins and the door to the feed room closed.
  • Give the horse unlimited access to fresh, clean water, except immediately after exercise, when the amount should be regulated.
  • Make changes to routines slowly and progressively, to avoid stress.

Pathology

The digital laminae are responsible for suspension of the axial skeleton of the animal within the hoof and dissipate concussive forces during locomotion. There are about 600 pairs of interleaved laminae: the epidermal laminae attached to the hoof wall and the dermal laminae attached to the coffin bone. Laminitis results from a compromise of this interaction, the mechanism of which remains unclear and is currently the subject of much research. Laminitis literally means inflammation of the laminae, and while it remains controversial whether this is the primary mechanism of disease, evidence of inflammation occurs very early in some instances of the disease.

Cellular and Molecular Biology of Laminitis

At present, three primary hypotheses exist for the mechanism of laminar failure. The first is classical inflammation, which includes infiltration of potentially destructive white blood cells. The second is ischemia-reperfusion injury. Researchers have observed both decreased and increased blood flow to the laminae. As ischemia-reperfusion injury reconciles both observations, it has received much attention in past years. Finally, metabolic derangements that lead to impaired cell function and proteolysis enzyme activation has been proposed to be the primary mechanism for development of laminitis.

Progression

In laminitis cases, a clear distinction must be made between the acute situation, starting at the onset of a laminitis attack and a chronic situation. A chronic situation can be either stable or unstable. The difference between acute, chronic, stable and unstable is of vital importance, when choosing a treatment protocol.

Laminitis can be mechanical or systemic, unilateral (on one foot) or bilateral (on two feet) or may also occur in all four feet.

Systemic laminitis follows from some metabolic disturbance within the horse, from a multitude of possible causes, and results in the partial dysfunction of the epidermal and dermal laminae, which attach the distal phalanx to the hoof wall. With this dysfunction, the deep digital flexor tendon (which attaches to the semi-lunar crest of the distal phalanx and serves to flex the foot) is able to pull the bone away from the wall, instead of flexing the foot. When the coffin bone is pulled away from the hoof wall, the remaining laminae will tear. This may lead to abscesses, within the hoof capsule, that can be severe and very painful.

Systemic laminitis is usually bilateral and is most common in the front feet, although it sometimes affects the hind feet.

Mechanical laminitis or "mechanical founder" does not start with laminitis or rotation of the distal phalanx. Instead, the wall is pulled away from the bone or lost, as a result of external influences. Mechanical founder can occur when a horse habitually paws, is ridden or driven on hard surfaces or loses laminar function, due to injury or pathologies affecting the wall.

Mechanical founder can be either unilateral or bilateral and can affect both front and hind feet.

Use of the Outlaw shoe in any phase of laminitis can improve the pain level and chances of recovery.