Overnight emergency shifts are a whole different world from daytime practice. For some reason, nothing becomes serious until the sun goes down, and then it's a matter of life and death, even if it's just that the dog is scratching at his ear.
One of the things that I saw a lot on overnight shifts and never during the daytime was dogs that had ingested the owner's drugs (legal or otherwise). This often led to the intersection of the most common presenting complaint ("my dog is acting weird") with the most common doctor's complaint ("these owners are acting weird").
Most of the time the owner would list what the dog had gotten into as the reason for coming in, and if that didn't work, going into the room to talk to the owner while wearing a white lab coat and a worried expression did the trick. The worst cases were the owners that wouldn't admit to the possibility -- then you might be stuck with a sudden behavior change as the only symptom. That can mean anything from a brain tumor to a liver shunt to just a dog doing weird things for no reason.
I once had three people come in with a fluffy four month old puppy at 2 AM on Monday morning. Their story was that they were playing with the puppy when all of the sudden it started barking and running around in circles and wouldn't stop. They swore up and down that there was no possibility of anything the dog might have gotten into anything. I even offered the standard out "Any possibility that your roommate might have had something?". All three said no. Of course, two of the three kept going off on tangents and had hard time staying focused on what I was asking. I could only hope that the third was the driver.
The physical exam was unremarkable -- the puppy was barking and a little hyperactive, but had a heart rate within normal limits and seemed to be responding to me fairly normally.
So... young stable dog, chemically altered owners (with no money, but with the grandmother's credit card). I ran some bloodwork (boringly normal) and kept the dog overnight on a fairly high fluid rate, hoping to help flush out whatever it had gotten into. Within two hours the dog had calmed down and it ate normally and slept the rest of the night.
I transferred the dog to Daters in the morning, then had to listen while one of the internal medicine faculty (who had a history of making snap diagnoses and complaining that the overnight doctor hadn't run enough tests) complained that I hadn't done enough tests overnight and that it certainly wasn't a drug ingestion and ... I left before he had finished so that I could go home and get my precious six hours of sleep before I had to be back again.
Funny followup #1: When I stumbled back in that evening, Daters said "Those people were totally on drugs." When he called the owner to update her about her dog, the woman fell asleep on the phone while he was talking. After going through this a few times, Daters ended up calling the grandmother (who was getting billed for all this) who told him "Those girls are worthless."
Funny followup #2: The clients wrote a letter of complaint about how rude Daters was. The only problem was, they complained about the ophthalmologist (whose name was nothing close to Daters), who had no idea who the clients were.
In any case, the dog was just fine.