Eleanor Kellon, VMD
ACV and clay won't get the job done. If the cracks are deep, clean them out with gauze and water with Fairy dish soap then rinse thoroughly using a small syringe and a cow teat cannula. Infuse with a mastitis antibiotic https://www.farmacy.co.uk/categories/159-milking-cow-tube , Cover the heels with a sanitary napkin held in place with a self-adhesive wrap https://www.farmacy.co.uk/products/555-vetrap-cohesive-bandage10cm-each . Repeat daily until healed.
Eleanor in PA