Okay, if the wound is in her back, she has a better chance of survival. Keep it clean and disinfected, and use some antibiotic ointment twice a day. The wound should eventually come together as long as there is not infection, and no internal injuries. If you cannot find Fish Mox, I would at least get some injectable procaine penicillin G and several syringes with 20 gauge needles. Inject 1/4 ml into the breast tissue once a day for 5 days. If you get the Fish Mox, give250 mg orally twice a day for 7 days. But a vet would be best. Let us know how she does, and try to get her eating and drinking.