Swelling, ulceration and running water on the dorsum of the foot may be caused by bacterial infection, diabetic foot, vasculitis and other factors. 1. Bacterial infection: for example, after the dorsum of the foot suffers damage, improper care, caused by bacterial infection, infection aggravated, will lead to the dorsum of the foot swelling, erosion, running water, accompanied by itching, pain and other symptoms. 2. Diabetic foot: secondary to diabetes, it will lead to abnormal or impaired sensation in the dorsum of the foot, and the skin color will be changed, and in the advanced stage, it will lead to local skin ulceration, vesiculation, swelling, and running water. 3. Vasculitis: when there is vasculitis in the blood vessels of the dorsal part of the foot, and the lesion is more serious, it will lead to localized swelling, erosion and running water, which may be accompanied by fever, fatigue, muscle aches and pains and other symptoms. Swelling, ulceration and water on the back of the feet indicate that there is an abnormality, and it is recommended to consult a doctor for examination and treatment.