Dogs with hookworm disease will lose weight, have a coarse, lustrous coat and shed easily. Digestive disturbances, vomiting, diarrhoea and constipation alternate. The faeces are bloody or black in colour and in severe cases become tar-like with a nasty putrid smell. If hookworm larvae invade the skin in large numbers, they can cause the dog to scratch itself constantly due to itchy skin and cause inflammation and erosion of the skin.
