A hard scab on a dog’s nose may be caused by trauma or skin disease. If there is hair loss, dander, itching, etc. in the scab, it is a skin disease and needs to be checked to see if it is a fungal infection or a parasite. If it is caused by infection, targeted treatment will be carried out. If it is a trauma, it will usually heal on its own after a week. You can also apply some trauma medicine on the dog, so that the recovery will be faster.