Dried, crumbled leaves, stored in a zip lock bag keep well. Steep about 2 table spoons full in a tea pot of hot water. When cool, strain. Squirt or bathe wounds with the Comfrey tea. Horses relax and look forward to this very quickly since it's soothing with no 'sting'.
Horses welcome continued treatment with comfrey for serious wounds.
Follow the bathing with a poultice of the crushed leaves or for straight cuts, the whole leaf, after steeping. Wrap with gauze or clean cotton strips to hold on. Reports on horses healing over and above the Vet's anticipation are many. Scarring seems to be less as well. For serious wounds follow your Vet's instructions with comfrey as an added step.