Equine Laminitis

Ponies are at risk for laminitis.

Equine laminitis may be one of the scariest diseases in horse nutrition...at least until you learn how to successfully manage it. The good news is that it can be successfully managed and prevented through nutrition.

According to the 2000 National Animal Health Monitoring System, 50% of the laminitis cases seen every year could be prevented through correct nutritional management!

Considering that almost 5% of horses that undergo surgery for laminitis end up deador humanely euthanized, it is in every horse owner's best interest to understand this disease and how nutritional management affects it.

Nobody ever wants to hear that their horse has laminitis, but it happens way too often in the horse world. In fact, this very serious disease is the second-leading killer of horses...only colic takes more equine lives each year.

What is laminitis in horses?

Equine laminitis is caused when the laminae become inflamed. In normal conditions, these soft tissues connect the hoof wall to the coffin bone and other structures within the hoof...much like Velcro is used to fasten two things together.

However, when the laminae become inflamed, the connections start to break, which causes catastrophic damage to the bones and other structures within the hoof.

The inflammation also causes a constriction of blood vessels to the area, leading to ischemia, or lack of blood, to the cells. When the cells cannot get the nutrients they need, they start to die, compounding the problems.

The Four Stages of Equine Laminitis

Developmental Laminitis

This stage is the time period between the triggering event and the first appearance of lameness. This period will usually last approximately 40 hours, and the horse will usually not show any symptoms during this period.

Common triggering events of equine laminitis include:

  • Over-consumption of grain or lush pasture
  • Prolonged high fever
  • Pneumonia
  • Potomac horse fever
  • Excessive stress
  • Unrelated lameness in another limb
  • Road founder or excessive prolonged concussion
  • Stall shavings that contain black walnut
  • Mastitis founder affecting lactating mares
  • Placenta retention beyond 12 hours
  • Colic, especially after surgery

It has been proposed (and substantiated by human medicine and limited studies in horses) that cold hosing and/or applying ice water to affected limbs during this period may prevent the progression of the disease.

In one study¹, 6 Standardbreds were dosed with oligofructose (given in amounts known from previous studies to induce laminitis in 100% of cases).

After treatment, one front foot of each horse was placed in a rubber boot with 50% ice cubes and 50% water while the other three feet were left untreated. For the entire 48-hours of the study, the ice was replenished to keep the level just below the carpus.

At the end of the study period, the untreated feet on all 6 horses had clinical laminitis, ranging from mild to severe. However, the treated feet on all 6 horses showed no signs of laminitis at all. The horses all tolerated the boots well, and showed no ill effects from wearing them.

Because the horses were humanely euthanized at the end of the study, it is still unclear whether or not the treated feet would eventually develop laminitis after the cold therapy was stopped.

However, the cold therapy during the developmental period of the disease clearly prevented the progression of laminitis. Due to these results it is thought that a horse that is a suspected laminitis case will benefit from cold therapy. Once the horse has started to show signs of pain, it is too late for the cold therapy to do any good, as the disease has moved on to the acute phase.

Acute Laminitis

The acute stage has one of two outcomes: either the horse makes it through the next 72 hours with no physical or radiological collapse, or the horse suffers a digital collapse (rotation or sinking of the coffin bone) and the disease moves into the chronic stage.

Subacute Laminitis

If the horse does not suffer digital collapse during the acute stage, he moves inot the subacute stage which lasts for 8-12 weeks. During this stage, the horse is considered to be recovering from the damage done during the developmental and acute stages.

Chronic Laminitis

If the horse does suffer a digital collapse during the acute stage, he is considered to have chronic laminitis. Thus, any horse that has suffered from rotation or sinking of the coffin bone is considered to have chronic laminitis, regardless of how long he displayed signs of pain during the initial onset of the disease.

Nutritional Management of Equine Laminitis

One of the easiest ways to prevent laminitis brought on by over-consumption of grains is to properly store your feed to ensure that the horses have no access to it. If you have smart horses in your barn, this may mean measures as drastic as padlocking the feed room door and/or feed bins.

To prevent most cases of equine laminitis caused by over-consumption of lush pasture, ensure that horses are slowly introduced to pasture whenever they have not had constant access to it for some time. Most generally this will be in the spring, but can also be in the fall, if they have been removed from the pasture during a late summer drought period.

To prevent laminitis from being triggered by an upset to the pH and digestive process in the lower digestive tract, it has been suggested that any meal given to horses contain no more than 2-4 grams of starch per kilogram of body weight.

For a 1000 pound horse, this means no more than 1-2 kg (2.2-4.4 pounds) of starch each meal. Therefore, if a horse is being fed a grain product that is 30% starch (which many on the market are that or higher) that means the safe upper limit for each meal in this respect is anywhere from 7-14 pounds.

Lush pasture triggers laminitis.

Lush pasture is often a problem because of the water-soluble carbohydrates such as glucose, fructose, and fructan. These substances are thought to cause problems in hind-gut fermentation similar to the problems caused by excessive starch. These digestive problems then trigger equine laminitis.

Therefore, it is prudent to limit pasture access to horses with chronic laminitis, or at risk for laminitis, during periods when these substances are at high concentrations.

In general, the concentrations are going to be high in spring, intermediate in autumn, and lowest in mid-summer.

However, the levels also fluctuate daily, based upon when the plant is creating and storing energy. The levels tend to rise during the morning hours, reaching a maximum in the afternoon, before falling during the evening and overnight hours. Therefore, the levels during the afternoon may be 2-4 times greater than the levels in the same pasture during the morning hours and overnight hours.

Removing laminitic horses from pasture during the day and turning them out for grazing overnight will help minimize their intake of these water-soluble carbohyrdates.

For the horse with chronic laminitis, it is prudent to keep his body weight within a desirable range. Overweight horses bear more weight on each limb than those at an ideal weight, so keeping these horses at an ideal weight will minimize the impact and trauma on the affected limb from daily activities.

It is also essential that these horses receive a high nutrition level so that they have adequate nutrients necessary to repair and maintain hoof quality. For many of these horses, like Babs, a ration balancer can be an ideal solution, providing minimal calories and high levels of nutrition.

Knowledge of equine laminitis and how to prevent it can assist you in preventing this disease in your horses. Because it is such a devastating disease, and treatment success rates plummet so rapidly, it is essential that horse owners treat any suspected case of equine laminitis as if it is an actual case, until it has been determined that the hoof pain was caused by something else.

I hope that you are lucky enough to never have to deal with equine laminitis personally, but now you have more knowledge of the disease in the event you need it.

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¹Worster, A.A., E.M. Gaughan, J.J. Hoskinson, J. Sargeant, and J.H. Erb. 2000.Effects of external thermal manipulation on laminar temperature and perfusion scintigraphy of the equine digit. N.Z. Vet. J. 48:111-116.