Wow, interesting question. Even though they may be able to, if you are paying for their services they need to actually go through a diagnosis. With both pituitary tumors and ear infections, the rat may be tilting his/her head, so sometimes it can be hard to tell which it is if the tumor is too small to be seen from a distance. If the tumor is big enough to be seen and very large, sometimes the vet can comfortably make an immediate diagnosis. I personally would not be comfortable paying a vet to look at my animal and told told that “they just know.” If you can see a large tumor maybe that’s ok then.