Life Saving Surgery for Chip!! Please help!

My name is Rebecca and I recently rescued a sweet dog named Chip. He is a Springer Spaniel, who endured two years of a cancerous tumor growing in his anal gland. He had not seen a vet for over 2 years, while the tumor continued to grow. I agreed to rescue him from this terrible existence. I was so relieved when yesterday the vet told me that the x-rays showed that the cancer has not spread yet, and the surgeon said removing the tumor as soon as possible is the best chance for him. The surgery is scheduled for two weeks from now. It is expensive - $3,500. I have already spent out of pocket more than 1,500 on his medical care, including x-ray, scans and bloodwork. The vets have told me that adenocarcinoma can be a very aggressive cancer. Chip is 10-years old, and the vets have told me his health is very good other than the tumor. He has already formed a special bond with his sister, Sophie, my other dog. And he is forever trying to make friends with Tigerlily, the cat, but she’s not having it.

Any help will be so greatly appreciated. Let’s give Chip the chance he deserves.