My rule of thumb has always been that I have enough money for basic care/food/etc and enough money/a humane method to end any animal's suffering that is within my care. That said, I've certainly spent plenty of money on my animals. But, I'm certainly not saying that with pride. I've found I've sent some vets on some really nice golf trips (and had the lovely opportunity to hear a vet who did not perform the procedure they were paid to do brag about said golfing) and actually prolonged my pets' suffering at the same time. The ethics involved with spending a large amount of money on things like pet rabbits as opposed to the world and people around me makes me uncomfortable at best. Spending a large amount of money on pets didn't make me a good person or my pets any happier or more loved, just as having more money than the next person isn't a reliable indicator that I am decent, responsible, smart, hard working, etc.
When looking at buying a house, attending college, etc, advice should include a percentage of income to set aside, a concrete dollar amount, etc. These numbers will still differ depending on who is listing them, but they at least allow for people to make assessments and to critically compare advice given. "Don't go to college if you can't afford it" probably isn't going to be the revolutionary statement that ensures that only people who can afford college attend. Likewise, statements that only cover what amount to save miss larger issues about how wealth, money, and political voice operate in various countries, let alone individual circumstances where one can have plenty of money and the suddenly not. These issues are far reaching and are done a great disservice by what amounts to bumper sticker slogans.
Of note, one can never bring their animal to a vet and still vaccinate for things like rabies. Many of the rural folks I know order in and administer vaccines. Farm supply stores and farm catalogues allow for this.
I hope that the OP will return and update on the dog, and that the dog has been responding to the treatment administered by them. Hoping to see more suggestions given that will and can be utilized to treat this dog.