Is it cut or is there a scab? Do you have pictures? You can use a disinfectant such as 2% chlorhexidene, weak Betadine iodine, or aoap and water to clean it. Plain Neosporin or Triple Antibiotic Ointment is fine to use. Gentamycin spray might help if there is infection, but gentamycin usually only treats certain bacteria, usually gram negative bacteria, such as E.coli. It would not be a good choice if you are seeing bumblefoot which would likely be a gram positive bacteria such as staphylococcus.