Dog displaying weird symptoms

[lpoet31]

Hello.

I have an older dog who had a few seizures last year, roughly 4, that were treated by a vet who did not think she developed epilepsy. The last seizure was in December and after treatment with fluids and medication, she seemed fine.

Then in the latter part of January something bizarre happened. She was in a very deep sleep and started to "run." She was moving her legs as if she were running really fast, her breathing became very, very labored, and then she started to snort. She stopped moving her legs, she did not go rigid, and she lifted her head. She did not focus on anything and she swayed her head side to side. I called her name several times but she did not seem to be awake or aware of where she was. She did not evacuate or defecate, her breathing calmed and after roughly 45 seconds she seemed to come out of it. She has done that ONLY at night and ONLY when she is seems to be in a very, very deep sleep. She can walk fine afterward and doesn't seem to suffer any ill effects. But I have no idea what it is. The vet also seems confused because they are not seizure symptoms but they sort of mimic seizures?

Has anyone experienced this with their dog? Is this a sleep disorder or a very specific type of seizure?

Any help would be greatly appreciated.
Thank you,
Tomi