Can you get a credit card?
I know where you are coming from - I had my 29 year old horse put to sleep last year after running up 4.5k vets bills - his was all age related, so he would never get better.
In treatment of abscesses - both my buns had to have an operation - Flint had one on his side & they had to cut away all the infected tissue - his abscess was tiny, the wound was not. Think it was about £120, but a few years ago. I would probably look around for vets - explain your situation & maybe they can offer credit terms? Took me a year to pay off my horse's vets bills - & tbh only did then cos my other horse needed his jabs.
Vets are running a business, but sometimes they can offer financial support - I couldn't have done mine without my horse vet - & my rabbit vet lets me hold an account