Maybe it's different for mice or in your country, but I've lived in several rural and urban areas in the US and was able to find an exotic vet for my rats (or a general vet willing to treat exotics) within an hour's drive of each location, albeit after significant searching. I've also had a mass surgically removed from one of my older rats and he went on to have another year of quality life.

Edit: Euthanasia is important too. Mice and rats are prone to respiratory failure, which is a slow and agonizing way to go. I watched one of my rats die from pneumonia inside my oxygen chamber just two hours ago, and it was horrifying. I deeply regret not making the 90-minute drive to the emergency vet for a euthanasia last night, as I have done many times before. It usually costs me about $150-200 these days.

[–] Saapas@piefed.zip 4 points 1 month ago* (last edited 1 month ago)

Rats are different to mice in that respect. They're bigger and live longer so it makes sense to treat them. Mice are so tiny, pretty delicate and live for a fairly short time so from the perspective of giving the animal best possible life it doesn't (in our opinion) make that much sense.

Not many vets are familiar with mice, there are those that are but it's just often not thought of as good for the animal to necessary start intensive treatments or especially do surgery. Usually the issue is cancer anyway and surgery for that just puts the small bugger in stress and pain for very little gain.