What is the most common cause of laminitis?

Im not sure what the MOST common cause of laminitis is but i know some of the things that could cause laminitis.

If your horse is overweight, resistant to insulin, has a high porportion of grain in his diet, has had laminitis before, comes from a bloodline prone to laminitis, has access to lush or improved pastures (grazing rich pastures can lead to laminitis), has cushings syndrome, or excessive fat on his crest area.

If your horse has any of the things above he could be at risk for laminitis