The interviewer understands that a day in the life of a veterinarian can have several emotions. Questions like this give you an opportunity to let the interviewer see a side of you that is 'reachable', so to speak. When something that can be rewarding can also be heart-wrenching at times, but you press on, this shows your true love for what you do.
"It's often both things at the same time. In the emergency room, we see everything from a mild case of the sniffles to life-threatening trauma, poisoning and even cancer. You have to be ready for anything at all times. With that said, we see a surprising amount of normal, routine stuff."
"You are right; there are days that one case makes you feel like you can walk on water and the next one makes you want to shut the door and cry a while. One of the most heartbreaking things isn't the horrible trauma case--I can usually fix that. Rather, it's a dog who had early signs that we could have picked up on but now things have gotten so serious that it's very difficult to treat. The other thing that's incredibly heartbreaking is when finances come between a pet and the family and getting the pet better."