Stand by Mack and Freyja in Their Battle

My name is Mack, and one of my best friends has cancer - a mast cell tumor - in her leg. I rehomed Freyja in 2020, in the middle of the pandemic when I was a lonely kid fresh out of the house I grew up in. And she was my only family for a long time when I was no-contact with my parents, and then later when I was homeless, and through several unhealthy relationships. She's been my stalwart shield and ever present buddy for five years, and the vet says this will take her from me before we get another five with her if it doesn't get removed. I'm asking humbly for your help, this is the cheapest vet we could find and I want to keep my best friend for as long as possible.