If Ivory spends a lot of time outdoors many times the tips of ears can be affected by fly bites. If that is the case you can use topical fly spray or ointment on her ears to repel the flies. If not flies sometimes ear tips may get crusty from an abnormality in blood flow to the edge of the ears. I would recomend a vet visit to have it assessed if it doesn't seem to be fly bites.