Many people use laminitis and founder interchangably. And whether you do or you don't is irrelevent, however, founder is indicative of the actual separation of the sensitive and insensitive laminae and the increase in the angle of separation of the third phalynx from the hoof wall. Many times, the third phalynx will 'sink' through the sole of the affected horse's foot - but not always. Lamintis refers simply to the inflammation of the laminae. An increase of blood flow to the laminae without the proper circulation and return of the blood away from the laminae. This 'mild' form of laminitis can be brought on by any major metabolic change in the horse, from the sudden increase in nutrient quality/quantity to extended regiments of steroids or other drugs to extreme extertion where the feet take a brutal beating - and it can also happen for no reason at all. Horse professionals think that they know what causes laminitis, but we can only speculate. Founder is actually a very advanced stage of laminitis. A horse can heal from mild laminitis with little to know effects, they can also completely recover from founder (much less likely) but soundness is never the same.