'Sudocreme' is an excellent product for some conditions - it is an over-the-counter medicated cream aimed primarily at the treatment of nappy rash. It contains a water-repellent base (consisting of oils / waxes); protective and emollient agents; antibacterial and anti-fungal agents; and a weak anaesthetic. It can also be used to treat eczema, bedsores, acne, minor burns and sores and minor wounds.
Whether it would help anal ulceration I really don't know, but it's widely used by dog owners, certainly worth a try.