Laminitis is described as a disease of the hooves of cattle and 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.
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.
Whatever the causative factors, and these may be individual, several or additive (there may be factors at play but insufficient to tip the hoof over into laminitis) the affected area experiences several factors.
Firstly, there needs to be initiators. These are generally pro-inflammatory factors but can be quite diverse. There are direct physical factors, such as standing on a stone or nail that initiates wound healing; again it can be a nutritional factor – overloading the hindgut with protein and starch leads to microbial population changes and death, resulting in endotoxins that are absorbed and induce inflammation; a third route is through disruption of the metabolism where obesity releases pro-inflammatory factors, and hormonal dysfunction – IR, Cushing’s etc. – can lead to metabolic inefficiency and the release of oxidative factors.
Secondly there need to be systems that exacerbate the inflammatory and oxidative factors which can disrupt the normal cycle of healing/regeneration that inflammation initiates. When the body experiences events that it distinguishes as abnormal, it responds with automatic defence that starts with the release of inflammatory factors. This is the start of a cycle of inflammation, to “ringfence” the zone of malfunction, followed by specific repair, followed by the release of anti-inflammatory factors to return the site to normal. However, there are times where this cycle is disrupted and one of the major disruptors, in the case of laminitis, is the actual positioning of the hoof itself.
All cells in the body are supplied and maintained by the vascular system, Blood is pumped from the heart delivers nutrients, oxygen and metabolites and then returns carrying waste, carbon dioxide etc.; this is against a pressure gradient and the further from the heart the lower the pressure. As hooves are the furthest point blood pressure is low and inflammation further restricts blood flow. Some absorbed endotoxins are also vasoconstrictors (amines from hind gut microbial death and absorbed through the “tight spaces” between the gut wall cells) further restricting blood flow. This leads to pooling and a cessation of the turnover of metabolites. One of the major consequences is hypoxia (oxygen restriction) leading to reperfusion and an increase in inflammatory activity.
Thirdly, and this may seem a contradiction as glucose (as sugar or starch) is a major component in laminitis, factors that restrict the normal delivery of glucose to the cells of the hoof, increase hypoxia. If there is no glucose at the cellular level cellular dysfunction occurs and can lead to release of MMP (matrix metalloproteinase – also stimulated by inflammatory cytokines), and the separation of the lamella.
Finally, the more identified cause of laminitis, hind gut overload, contributes by delivering inflammatory factors, vaso-constrictors and MMP release, all of which lead to lamellar separation.
What is emerging is a cycle of negative effects. Although initiating inflammation is a normal, and in most cases, a beneficial effect, the restriction of blood flow, hypoxia and released of MMP all cause a downward spiral of increased pro-inflammatory cues. Reduced blood flow cannot remove the pro-inflammatory and oxidative factors, which drive up inflammation.
Although the causative factors are varied and complex, at the hoof level it is the build up of pro-inflammatory factors, oxidative damage and reperfusion that cause the actual damage, and it is in this arena where bioactives may exert an effect.
When feeding the laminitic, attention is payed to 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), all husbandry techniques to reduce the causative factors. 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.
However, a more targeted approach may also help in avoiding laminitis. When helping to ensure the normal inflammation and oxidative cycles run smoothly, turmeric has a role.
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.
Turmeric has a number of components that can have a role in this negative cycle. Although its principal bioactive is curcumin, it also has a number of essential oils and sterols, all of which can act in this cycle. Turmeric has strong antioxidative properties and has been reported to increase GTP and SOD activity. As such this would help suppress the pro-oxidative NOX and superoxide, providing a brake on the pro-inflammatory cycle.
Curcumin inhibits the production of both interleukin and the TN factors involved in the release of MMP, whilst also downregulating the release of chemo-attractants without which fewer pro-inflammatory factors arrive at the damaged site.
The essential oils also have a role in the inflammatory cycle. They 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 turmeric can support those regulatory factors that return stress factors to normal.
However, turmeric is not the only factor in TurmerAid. Bioavailability is an important factor to ensure that dietary bioactives reach the active area and the inclusion of piperine to downregulate glucuronidation and yucca saponins to improve absorption allows the curcumin, terpenes and phytosterols circulate to the hooves. Additionally,
bioactives from apple cider vinegar – chlorogenic acid and quercetin – support the antioxidative route to a similar way to turmeric, but also offsets glucuronidation, so increasing overall bioavailability. Additionally, the inclusion of omega-3 fatty acids also ameliorates inflammatory process through its role in PGE2 regulation.
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.
TurmerAid contains powerful antioxidants, components that help ensure normal inflammatory control and metabolites that extend the bioavailability of the actives. As part of a regime for feeding the laminitic horse, TurmerAid has many benefits.
Dr Tom Shurlock BSc PhD