Reese's emergency medical expenses

I had recently brought my dog into the vet because she was having some digestive issues and some shoulder issues. Since then her health has went down hill quickly. She is no longer walking on her front right paw. I am afraid to loose my best friend . She has been with me for the past four years and has helped me deal with a lot of emotional issues from leaving my family and making a big move and deaths . I want to make her as comfortable as possible . I normally wouldn't do this as I feel I can make payments on my own, however the vet is asking for the payment up front. Any little amount would help . And please leave a name as to where I can pay you back or even do something for you . Once again any little amount will help please and thank you .
-Brian