I need to know the proper dose of levaquin for a 72 pound German shepherd. She has an infected skin abcess.?

She is otherwise healthy. I have been squeezing out the puss daily and applying antibiotic ointment and cleaning with hydrogen peroxide. Though there is much less puss than in the beginning, it is still there nightly. I do not have access to a vetrinarian here. The only antibiotic I have is the Levaquin 750mg tablets. 14 days worth. I can cut them if needed.