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The Role of Fructans in Equine Laminitis

The Role of Fructans in Equine Laminitis

 C.C. Pollitt School of Veterinary Science, University of Queensland, St Lucia, Qld 4072 

Proc. Aust. Equine Sc. Symp., Vol 1, 2006

Laminitis is one of the most serious and debilitating diseases of the equine foot. It causes permanent structural damage and crippling functional changes in the hooves. In Australia, where horses often graze on improved pastures designed for ruminants, laminitis is a common and growing concern especially due to grass-induced laminitis, also known as grass founder. 

The Role of Fructan in Grass-Induced Laminitis 

Modern pasture grasses are selectively bred for high fructan content to benefit ruminant livestock. However, this poses a major risk for horses. In certain seasonal conditions particularly during cool nights and sunny days in spring and autumn, fructan levels in grass spike dangerously. These high concentrations can trigger laminitis in grazing horses. Key environmental factors that elevate fructan levels include: Drought-breaking rain: promotes new growth rich in fructans Overgrazing or reduced irrigation: surprisingly increases fructan concentration Spring and autumn weather patterns: promote rapid fructan accumulation 

Experimental Evidence Linking Fructan to Laminitis 

Research has shown that feeding horses 3–4 kg of purified oligofructose (OF), a commercial-grade fructan, almost always induces laminitis. In the hindgut, this excess fructan is rapidly fermented, leading to an overgrowth of Streptococcus bacteria disrupting microbial balance and initiating inflammatory pathways. 

Laminitis Trigger Factors (LTFs) and Enzymatic Damage 

Within 24 hours of OF ingestion, laminitis trigger factors (LTFs) are generated in the bloodstream. These LTFs lead to the activation of enzymes known as matrix metalloproteinases (MMPs) in the lamellar tissues of the hoof. MMPs degrade laminin-5, a critical protein that anchors the inner hoof wall lamellae to the distal phalanx. The destruction of this anchoring system leads to attachment failure between hoof and bone, which is a hallmark lesion of laminitis. 

Vascular Changes and Enzyme Activity 

 If the foot’s circulation is dilated during the early stages of laminitis, the condition tends to be more severe. That’s because increased blood flow delivers more LTFs to the lamellar tissue. However, despite decades of belief, recent molecular studies show no evidence of ischemia or reperfusion injury as part of laminitis pathology. 

Prolonged Limb Cooling: An Effective Preventative Strategy 

Since discovering the enzyme-dependent nature of laminitis, researchers have found that prolonged cryotherapy (cooling the lower limbs to 2–5°C) can prevent the disease altogether. 

  • Cryotherapy slows MMP activity 
  • It also causes vasoconstriction, limiting LTF delivery to the hooves 
  • Horses tolerate limb cooling well, and it causes no harm 

Toward Smarter Laminitis Management 

What Needs to Be Done:

  • Identify and block laminitis trigger factors (LTFs) 
  • Manage pasture to reduce fructan production 
  • Adapt horse management to limit fructan intake 
  • Target hindgut bacteria that ferment fructans 
  • Feed low NSC feeds  such as Coolstance copra 

Conclusion 

There is now a clear link between fructan-rich pastures, hindgut fermentation, and the enzymatic cascade that leads to laminitis. This breakthrough understanding paves the way for rational prevention and treatment, including distal limb cryotherapy and strategic pasture and diet management. While the road ahead is challenging, especially in designing field-level interventions, the science is catching up and a future without grass founder may no longer be out of reach.


Scientific Articles laminitis nsc ulcabuf hindgut acidosis fructan grass founder copra