Keep the wound clean. I would take that paw and plop it in a bowl of betadine. It is the stuff all vets and doctors use when they do surgery. Looks like iodine. You can get it at the drug store for a few dollars. Keep applying it every day. You might want to borrow some money for vet service. I know it can get expensive, but ..... dog ownership is just that... you need to sell something or borrow if you can. Good luck.