Help Margo !!

On the night of Thursday, November 8th, I happened to look out my front door and saw a stray dog limping down the street in front of my house. I went outside and called for the dog and it immediately came to me. I noticed the dog had a massive (football size) growth / tumor, that was infected, hanging from her abdomen area. After a late night emergency room vet visit, the veterinarian indicated the tumor was not immediately life threatening but need removed ASAP. The veterinarians office estimated the price of this procedure to be $600.00. After this surgery is performed, she will the be spayed which will be additional $200.00. The dog has since been named Margo and is living in our home while she awaits her first surgery, which is scheduled for Tuesday, November 13th. Margo is a beautiful blue nosed Pitbull, who is very friendly and outgoing. She responds to basic commands and has a very sweet demeanor. I believe she was used for extensive breeding and upon developing the tumor / medical condition was abandoned by her owner. Margo was found with no collar nor tags indicating that she was lost or abandoned. Social media searches were made, along with door to door attempts to find her owner. No one has came forward or recognizes the dog. Again, this leads me to believe she was abandoned in our neighborhood due to her condition. Margo is an amazing, super friendly dog and will make a wonderful pet. Due to having other animals to care for and this unplanned surgery expense, help would be greatly appreciated.Thanks !