Founder in horses, also known as laminitis, is caused by inflammation and damage to the laminae, the sensitive tissues that attach the hoof wall to the coffin bone inside the hoof. This inflammation can lead to rotation or sinking of the coffin bone, causing severe pain and lameness

Main Causes of Founder in Horses

• Insulin Dysregulation and Metabolic Disorders:
  Over 90% of founder cases are linked to high insulin levels (hyperinsulinemia), Equine Metabolic Syndrome (EMS), and Cushing’s disease (PPID). Insulin resistance disrupts normal laminae health and is a major cause, especially in overweight or older horses

• Dietary Factors:
  Excessive intake of carbohydrates, sugars, and starches-such as from lush pasture, grain overload, or sudden ingestion of large amounts of feed-can trigger founder by causing abnormal digestion and reduced blood flow to the hooves

• Acute Illness and Systemic Inflammation:
  Severe illnesses like colic, high fevers, sepsis, or retained placenta can cause systemic inflammation that affects the laminae and leads to founder

• Mechanical Founder:
  Prolonged excessive weight bearing on one limb due to injury or lameness can reduce blood flow and cause laminitis in that limb, known as mechanical founder

• Toxins and Environmental Factors:
  Exposure to certain toxins (e.g., black walnut shavings) or compromised gastrointestinal health can increase susceptibility to founder

• Steroid Overdose:
  Rarely, high doses of steroids like dexamethasone can precipitate founder

Additional Risk Factors

• Obesity increases pressure on hooves and ligaments, contributing to inflammation and founder risk

• Certain breeds (draft horses, Morgans, ponies) and older horses are more prone to the condition

• Sudden changes in diet or environment, cold water intake by overheated horses, and standing for long periods can also contribute

Founder is a complex condition often resulting from a combination of metabolic and environmental factors. Prevention and treatment focus on managing underlying causes, proper feeding, hoof care, and minimizing risk factors

. This summary integrates information from multiple expert sources to provide a clear overview of what causes founder in horses.