THE BASICS: Laminitis is essentially a condition resulting from impaired blood supply to the cows hoof and is believed to be the primary cause of Ulcers, White Line Disease\Abscesses and heel erosion.  Wide, square ended "duck feet" and double soles are also thought to be an end result of Laminitis.  Laminitis is thought to be caused by either poor diet, sickness, improper housing and management practices and is often times a combination of these factors.  It manifests itself  as Sub-clinical Laminitis, Chronic Laminitis and Acute Laminitis.  The first indications of  Laminitis (except in the case of Acute Laminitis) are yellowish discoloration of the sole and/or streaks of red throughout the surface of the sole with concentrated pockets near the end of the toe and near the heel along the  inner wall of the hoof.     The actual causes and resulting problems associated with Laminitis are complicated and multifactorial. The following links are more in depth analysis of the underlying causes and various manifestations of Laminitis. 

Check out Dr. Paul Greenough's Encyclopedia of Cattle Lameness at www.cowdoc.net, an excellent resource on cattle lameness put together by Dr. Paul Greenough and other professionals. 

Pathogenesis of Laminitis