Dietary and other Influences on Laminitis: A Brief Scientific Overview
Laminitis is a complex and painful condition affecting the laminae of the hoof, often triggered by systemic disturbances originating in the gut. One of the most significant contributors is diet - how and what a horse consumes.
Starch Overload and Hindgut Dysfunction
Small Intestinal Overload
Horses are physiologically adapted to digest starch primarily in the small intestine. However, when large quantities of starch are ingested - such as from high starch, grain-rich meals, or lush pasture - the digestive capacity of the small intestine can be exceeded, which leads to a cascade of problems...
Hindgut Fermentation and Acidosis
Undigested starch passes into the hindgut (caecum and colon), where it undergoes rapid fermentation by lactic acid-producing bacteria. This leads to a sharp increase in lactic acid levels in the gut, and consequently a significant drop in pH, resulting in hindgut acidosis.
Microbial Disruption and Endotoxin Release
The excessively acidic environment disrupts the normal microbial balance, killing beneficial fibre-digesting microbes. As these microbes die, they release endotoxins into the gut.
Compromised Gut Barrier and Systemic Inflammation
Acidosis can damage the gut lining, allowing endotoxins and vasoactive substances to leak into the bloodstream through the compromised gut lining. This leads to a systemic inflammatory response, which can affect circulatory flow to the hoof and damage the laminae, initiating laminitis.
Impact of Sudden Dietary Changes
Abrupt transitions from a high-fibre to a high-starch diet can also destabilise the gut microbiome. The rapid microbial turnover results in the release of microbial toxins into the bloodstream, mimicking the cascade seen in starch overload and potentially triggering laminitis.
Toxin-Induced Laminitis
Internal Toxins (Endotoxemia/Sepsis)
Laminitis may develop secondary to systemic illness where inflammatory mediators or toxins enter circulation. Common triggers include:
- Colitis (intestinal inflammation and diarrhoea)
- Retained placenta post-foaling
- Severe infections such as pleuropneumonia
External Toxins
Exposure to certain toxic substances or plants can also induce laminitis. A notable example is black walnut shavings, which can cause laminitis through skin contact alone. Ingested plant toxins may directly disrupt vascular or inflammatory pathways, depending on the specific compound involved.
Post-Colic Laminitis
Colic, which involves gastrointestinal inflammation and dysfunction, can predispose horses to laminitis due to the systemic inflammatory response and potential endotoxin release.
Corticosteroid-Induced Laminitis
The prevailing hypothesis is that corticosteroids exacerbate pre-existing metabolic dysfunctions:
- They impair insulin sensitivity, increasing insulin resistance.
- In horses with Insulin Dysregulation (ID) or Equine Metabolic Syndrome (EMS), corticosteroids can provoke a temporary spike in insulin levels (hyperinsulinemia), which is believed to be the direct trigger for laminitis.
Endocrinopathic Laminitis
This is the most prevalent form of laminitis, resulting from hormonal imbalances that lead to Insulin Dysregulation (ID). It is distinct from sepsis-associated laminitis. Horses with endocrinopathic conditions are predisposed to laminitis, thus, dietary management of the conditions is absolutely paramount to maintaining their optimal health.
Key underlying conditions include:
- Equine Metabolic Syndrome (EMS): Characterized by obesity, regional adiposity (e.g. cresty neck), and insulin resistance.
- Pituitary Pars Intermedia Dysfunction (PPID): A progressive disorder of the pituitary gland, which coexists with, or contributes to, insulin dysregulation by disrupting normal hormonal function, including cortisol.
Finer Forage was founded with a clear purpose: to offer feeding solutions that align with the natural dietary patterns horses have evolved to follow. Our products are grounded in scientific, evidence-based nutrition, formulated to deliver species-appropriate feeds and supplements for optimum health. We never us by-products, cereals, soya, molasses, alfalfa, or any other ingredients that aren't 100% beneficial to the horse.
