WHAT IS FOUNDER OR LAMINITIS?

When a mule or donkey founders, it is commonly defined as inflammation of the sensitive laminea of the hoof.   In some severe cases, rotation of the pedal bone (within the hoof) happens, and that may progress to perforation of the sole.   The disease is a local manifestation of a more generalized metabolic disturbance, and the hoof problems are classified as acute, subacute, or chronic.  It can develop on two feet or all four feet. 

The most common causes of laminitis are ingestion of excess carbohydrate (grain overload) and grazing of lush pastures.  The risk is higher in equines that are overweight and unfit.   Incidence of the acute and subacute forms is higher whenever there is a flush of new grass.

There are disturbances in the circulation of the foot, which initially are reversible, probably cause the pain shown by the equine.   The end result, in mild cases, is production of “laminitic rings”.  In severe cases, pedal rotation or complete separation of the hoof from the underlying tissues occurs.   If the separation occurs rapidly, the pedal bone may sink within the hoof.  In chronic cases, the pedal bone may penetrate the sole just in front of the frog.  The prognosis in severe cases is poor because the changes become irreversible, and secondary infection is common.   In subacute and chronic cases, the rotation of the pedal bone occurs relatively slowly.  The sole of the hoof tends to become convex and thickens, and the hoof alters shape to accommodate the new position. 

Both donkeys and mules can develop laminitis.   It is important to monitor your equine’s weight to help prevent laminitis.   Acute laminitis constitutes a medical emergency because pedal rotation can occur rapidly.   In some cases, both your veterinarian and your farrier may be called in to x-ray, diagnose, and treat the feet with corrective trimming, specialty shoes such as heart-bar shoes, and leather pads. 

Chronic laminitis is one of the most common causes of lameness in donkeys.  It occurs in successive years, when donkeys (frequently overweight) are turned out in lush pasture.  The signs are usually confined to the feet, and include the heat, (mild to severe) pain and abnormal gait seen in acute laminitis.  Like obesity, laminitis can be difficult to treat and is better prevented.  Limiting or eliminating pasture turn outs and feeding a good quality, lower protein hay should prevent most diet-related cases of laminitis.   Occasionally, the stoic nature of donkeys will allow laminitis to advance long before it may show evidence of foot pain.   Other indications might include occasional hoof abcesses or a donkey that lies down a lot.

For more information on Laminitis or Founder, consult with your veterinarian.  There are also many books available on the subject, including;

Donkeys - Miniature, Standard and Mammoth.  A Veterinary Guide for Owners and Breeders by Stephen R. Purdy, DVM

The Merck Veterinary Manual, Published by Merck & Co., Inc.

U.C. Davis – Book of Horses, A Complete Medical Reference Guide for Horses and Foals, Edited by Mordecai Siegal