Founder is the common name for laminitis, a condition of the hoof in horses and donkeys. Within the hoof, there are structures called laminae that attach the hoof wall to the coffin bone. Founder is always a symptom of another systemic issue occurring in the horses body. Although there are many factors that can lead to laminitis, it is most common in older horses. Ponies, Morgans, and draft breeds are at especially high risk, but the condition can be seen in any breed. Horses with a previous diagnosis of equine metabolic syndrome (EMS) or equine cushings (PPID) are also at increased risk for foundering. Founder is most frequently seen in the spring but can be seen at any time of year.

Symptoms of founder in horses can be acute or chronic:

Acute:

• Sudden lameness at the walk
• Increased heat in the hoof wall
• Increased digital pulses
• Hoof tester sensitivity over the toe of the horse

Chronic:

• Rings on the hoof wall
• Widening of the white line
• Sinking/flattening of the sole

There are five main causes of founder in horses: insulin dysregulation, acute illness, dietary indiscretion, mechanical founder, and steroid-induced laminitis. Insulin plays a very big role in the health of the laminae. Disruptions in the normal function of insulin in the horses body can result in founder. Obesity, EMS, PPID, and high carbohydrate diets can all contribute to insulin dysregulation and founder. Other factors that can cause laminitis include overfeeding, overweight animals lacking exercise, cold water intake by an overheated animal, accidental overfeeding, local infections, excess weight bearing on one or more legs, running on hard surfaces, and standing for long time periods in transport.

If a horse owner suspects that their horse has founder, they should consult with a veterinarian to obtain a precise diagnosis. Diagnostic blood testing may be used to help diagnose founder and determine the cause. Proper feeding, hoof care, and management are critical for supporting hoof health. If a horse is recovering from or at risk of founder, a balanced feeding plan can be developed to address laminitis risk and optimize hoof health.