When I first adopted Chloe, she had had "head tremors" at the kennel shortly after she had been diagnosed with hypothyroid and she started the soloxine.
When we adjusted her meds at home, she had had one or two as well.
As time went by, she didn't have any but we did notice that when there was high stress going on, she would have them. One time, I was really scared and brought her to the vet but it had stopped. Her pupils were diated and would not retract. She was scared to death so the doctor wasn't sure if it was neurological or she was so stressed about being there. (this was also the bottom of the totem pole vet after hours)
I've also noticed that as the spring rolls around, she will have a few. She had one about half hour ago. So far they have not lasted more than 5-6 minutes. My vet had told me if they last longer than 5 minutes of so, we should bring her in, but other than that there was nothing we could do but watch her.
This is what she is experiencing. When it is happening, she is alert, happy, receptive, will take a cookie, will come when called, etc. The only thing is her head is shaking. I get so scared when it happens.
When I had first posted about this, almost 2 years ago, there were one or 2 people who had dogs who had this. I know there are a lot of new pups on GT so I figured, I'd see if anyone else experiences this with their hound.