When a veterinarian is presented with your pet s/he has a process that is followed to help determine a diagnosis. One of those processes, that many vets follow, is called SOAP. This is a way they look at the “problem” that is being presented.
Subjective is what the client and vet can see looking at your pet. Is your pet panting, lethargic, frantic, scratching? Is the haircoat shiny, dull, flaky, is there alopecia? When you tell the vet what you’ve been seeing lately that makes you believe some thing is wrong, not eating, crying during urination, pacing, sleeping all day, these are all a part of the subjective information. This is the information gathering stage.
Objective is the information gathered from diagnostics such as radiographs, blood work, even taking of the temperature. The objective assists the vet in assessment.
Assessment is reading the the results of tests and other diagnostics so that they may rule out or confirm a diagnosis. S/He may find that more information is required as they have only come up with a differential diagnosis, meaning there are more than one possible diagnosis bases on the information. This leads to the next step.
Plan is what the veterinarian is going to do about what they have diagnosed. Treatment plan, prognosis and if s/he came up with a differential diagnosis what further tests may need to be done. Communication with the client is also a part of the plan.
This is just one way that a veterinarian approaches your pets health issues. By no means is it the only way.