Laminitis in Horses & Hoof Health
By: Dr. Lydia Gray
Laminitis is inflammation of the laminae, the tiny, interlocking fingers that attach the coffin bone to the hoof wall. A complex sequence of events occurs during laminitis, potentially altering blood flow or circulation in the foot, resulting in damage to this tissue. When the damage is severe enough, the laminae die and the coffin bone inside the hoof is no longer supported in the hoof. If the bone rotates or sinks in the hoof, the horse is said to have "foundered".
The leading cause of laminitis is pasture (grass sugar) overload, but it can occur after any number of compromising conditions in the body, including:
- Grain (sugar) overload
- Colic or diarrhea
- Uterine infection or retained placenta
- Equine Metabolic Syndrome (Insulin Resistance) or Cushing’s Disease
- Excess weight-bearing on a limb
- Infections in the blood, lungs or other organs
The classic signs of laminitis include:
- Shifting weight from foot to foot
- Painful-looking gait (described as “walking on eggshells”)
- Classic founder stance (leaning back so hind feet bear more weight)
- Warm feet, bounding digital pulses
- Sweating, increased heart and respiratory rates
- Reluctance to move or get up from lying down
Research has shown that ingredients such as essential fatty acids and hops may have the ability to interrupt the cascade of negative effects leading to laminitis after sugar, starch, and fructan overload. Once a horse has developed laminitis, there may still be a role for omega 3 fatty acids because of their properties which offset dangerous inflammatory effects. Other ingredients such as the antioxidant Vitamin E target the oxidative stress associated with this condition and may also be appropriate.
Horses that develop laminitis due to insulin dysregulation (insulin resistance and hyperinsulinemia) associated with Equine Metabolic Syndrome may benefit from supplements that contain chromium and magnesium, shown to support proper insulin and glucose (blood sugar) metabolism. Because healthy hoof regrowth is important, hoof supplements that contain biotin, methionine and other amino acids, plus zinc and additional minerals, may be recommended.
Your veterinarian will perform a complete physical examination to determine the extent of the laminitis and attempt to discover what may have caused it. They may take x-rays initially as a baseline, and again during a follow-up visit to look for differences (rotation and/or sinking) in the position of the coffin bone.
Since understanding what triggered the laminitis is key to managing the current condition as well as preventing future bouts, your vet may recommend bloodwork. Specific test protocols may point to Equine Metabolic Syndrome – and its insulin and glucose abnormalities – Cushing’s Disease, also known as Pituitary Pars Intermedia Dysfunction (PPID), or both.
Many horses with laminitis benefit from non-steroidal anti-inflammatory drugs (NSAIDs) like bute (phenylbutazone) for pain and inflammation. In some cases, Banamine® (flunixin meglumine) may be preferred as it also helps fight endotoxins. Antibiotics will typically be administered if an infection is present. Sometimes medications that dilate blood vessels, such as acepromazine or isoxsuprine, are given to help encourage better circulation in the foot.
Horses that develop laminitis due to Cushing’s Disease are usually prescribed daily Prascend® (the FDA-approved version of pergolide) to manage the underlying condition. Thyro-L® (levothyroxine) may be a useful prescription drug in the battle against laminitis in cases where obesity is thought to be a contributing factor.
Therapeutic Trimming and Exercise
As your veterinarian and farrier work together to support the hoof wall’s weight-bearing ability during the acute phase of laminitis, stall rest may be recommended. Later, as the horse becomes more comfortable and is cleared for light exercise, short periods of hand walking, individual turnout, and other movement may be gradually reintroduced. Follow your vet’s schedule carefully.
Diet (Hay, Pasture, Grain, Treats)
Depending on the root cause of the laminitis, your horse may be placed on a restricted diet. For example, if blood tests reveal disturbances with insulin and glucose metabolism, then the vet may recommend a low NSC (Non-Structural Carbohydrate) diet so your horse isn’t taking in excess sugars and starches. Forages (hay and pasture), grains, and treats that are 12% NSC or less are generally considered “low NSC.”
For hay, this means having it analyzed for NSC percent, since the levels of sugars and starches in hay can’t be estimated from just looking at it. If the levels are too high, it may be necessary to find an alternative source of hay. However, hay with an NSC between 12 and 20% can be soaked in water to help reduce sugars and starches. Slowing the rate of intake of hay by using a small hole hay net and limiting pasture by using a grazing muzzle (if grass is permitted at all), are additional ways to restrict the sugars, starches, and overall calories horses ingest.
When it comes to grain, the goal is to make sure the horse’s diet is still complete and balanced in terms of vitamins, minerals, and protein (amino acids) without providing non-structural carbohydrates and calories these horses likely don’t need. Talk to your veterinarian, but the best option may be a ration balancer or even just a multi-vitamin/mineral supplement. Most fortified grains on the market, or even plain cereal grains like corn and oats, may not be appropriate for a horse with insulin and glucose issues.
Likewise, avoid giving your horse treats that are mainly sugar, like sugar cubes, peppermints, and anything with molasses as the first ingredient. Opt instead for treats labels as low sugar and starch or try fruits and vegetables that also contain fiber and other nutrients. Watch the quantity too. Treats are just that, a reward for a job well done, and not meant to replace a meal (so don’t feed the whole bag).