Chapotraphouse

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.