Yes, but only AFTER you’ve softened the scabs. Apply an ointment directly to scabs and let it sit. When scabs become pliable, you can gently remove them. Then follow your primary care veterinarian’s instructions for ongoing treatment.
Avoid aggressive scrubbing or picking of crusty dry scabs – it is painful.
An important key to resolving scratches is housing the horse in a clean, dry environment. Modifying the living situation until the infection is under control may be necessary.