Diet and Laminitis

What is Laminitis?

Laminitis is described as a disease of the hooves of horses. As such, it is a little misleading as it is a consequence of disease, hormonal & metabolic dysfunction and poor nutrition, each of which may be described as disease. Laminitis is fundamentally a symptom of disease and relates to specific inflammatory, oxidative and circulatory malfunction in the specific area of the hoof.

What are the symptoms of Laminitis?

Symptoms of laminitis include raised temperature in the hoof, increased arterial pulsing, the classic founder stance, and general behaviour to avoid putting weight on the affected areas. All these symptoms also indicated what is happening in the hoof.

What causes Laminitis?

Laminitis is a disorder that is associated with overfeeding sugar and starch or water-soluble carbohydrates, which causes inflammation of the laminae.

It targets the lamellar (soft, connective tissue) that holds the hoof to the pedal bone, and the inflammation resulting in pain and lameness in horses and ponies.

Although laminitis is a disorder that is expressed in the feet, the actual physiology of laminitis involves poor circulation, vasoconstriction and pooling of toxins, pro-inflammatory factors, oxygen starvation and the inability of glucose to energise normal hoof metabolism.

The major instigators of these factors are endocrinological – obesity, insulin resistance PPID, dietary (too much fructans, sugars, overeating), or mechanical (bruising, wounds).

Does a laminitic need a special diet?

When feeding the laminitic, attention is paid to reducing causative factors by:

• Reducing weight (obesity leads to fat deposition which activates the release of adipokines, a form of cytokine which is an inflammatory mediator)
• Reducing protein intake (amine generation in hind gut) and starch (leads to lactic acid production in the hind gut that “loosens” the tight spaces and allows absorption of endotoxins)

On top of this there are strategies for feeding the IR & EMS horse, veterans (more prone to Cushing’s) and other endocrinopathic disorders, again all designed to reduce causative factors. 

How can diet help the laminitic?

Look to feed a low sugar low starch diet that may also be high in essential oils and sterols as well as antioxidant properties helping to ensure the normal inflammation and oxidative cycles run smoothly. 

Inflammatory factors involved in the aetiology of laminitis are released through the activation of neutrophils. Although neutrophils are generally regarded as macrophages and the first line response to infection, they also release cytokines generating inflammatory regulators such as interleukins and tumour necrosis factors. Neutrophils are activated by various laminitic factors such as endotoxins, reperfusion and oxidative factors. The released regulators impact on antioxidant enzymes (glutathione peroxidase, SOD) depressing them and allowing oxidative factors such as NOX and superoxide to increase oxidative stress and feed back into neutrophil activation. At the same time the regulators increase the activity of MMP, having a direct impact on cellular destruction in the lamellar of the hooves. 

The essential oils also have a role in the inflammatory cycle. They may help to lower PGE2 which has a role in eicosanoid production – both pro- and anti- inflammatory. It also impacts on vasodilation and so may help flush away pooled blood. 

As such, one series of components in the aetiology of laminitis revolves around a downward spiral of oxidative stress generating inflammatory cues that suppress antioxidative factors and so increase oxidative stress. Simultaneously the inflammatory regulators help generate MMP to cause physical damage to the hoof. By interacting at both the oxidative and the inflammatory stages of this cycle diet can support those regulatory factors that return stress factors to normal. 

Laminitis is a complex issue with many factors to its development. Dietary causes, and strategies can help in its control, but they can be more fully supported by the inclusion of bioactives in the diet.