My newly adopted dog had been home with me for less than 24 hours. I was proudly introducing her to my friend and we were all hanging out on the floor for gentle pets. All of a sudden, her head started shaking and she slumped down onto the floor. This continued for a few minutes, during which time I freaked out, my friend stayed remarkably calm, and I made an appointment to see the vet down the street. Luckily, she returned to her baseline, we got on the streetcar together and made it in to have her checked out as soon as possible.
I thought she had had a seizure, and so did the doctor. As it turned out, dog seizures were not as terrible as I thought they were, and I was told to watch and wait. If she had more than a couple more seizures this year, she should see a doggy neurologist and probably go on medication. It was an expensive visit and just generally pretty terrifying for both of us. I got in contact with the rescue back in Arkansas as well as the rescue she was at here in Toronto and we all combed through her vet records and any information they had, but no one had seen her have any random shaking episodes. After a good cuddle and a few treats, we shrugged it off, continuing on with our lives.
It happened again a couple of weeks later while we were all cuddled up on the couch with my partner and our cat. This time, I turned on my phone and took a video to send to the vet. After taking the video and uploading it, I thought to check out YouTube to see if there were any similar videos taken by other worried dog owners. As it turns out, there were pages and pages of shaking heads, worried humans and a diagnosis: idiopathic head tremors.
Idiopathic means that they’re of unknown origin, but they don’t seem to be in any way harmful. Being the nerd that I am, I checked out some peer-reviewed journals of veterinary medicine to see what the long-term effects would be and it seems that they cause no discernible damage and that dogs with these tremors live long and otherwise healthy lives. Dogs are entirely conscious during the episodes and can sometimes be brought out of it by being presented with a treat. (As far as we know, this is not simply an elaborate ploy.) They don’t experience pain or stress, so its only impact is on the worried human. As soon as an episode passes, which is usually about three minutes, they’re totally fine.

It does seem to be a bit more prevalent in bully breeds, boxers, Dobermans, and Labradors, but any dog can be impacted. The tremors often show up in young adulthood and stick around for a few years, resolving entirely by themselves. They don’t interfere with other parts of a dog’s life and don’t require any special treatment.
Once I came to the vet with this information, he agreed that it sounded most likely. We’re still going to keep an eye on her, but she actually hasn’t had another episode since, at least not in our presence. Keep in mind that this is not advice in lieu of veterinary care. This is information that may be useful as part of a full workup when your dog exhibits similar symptoms to ensure that you get an accurate diagnosis.