Had that happen to our Shih Tzu, went out to the bathroom and collapsed.
Was diagnosed down at LSU with some neurological condition, they used an acronym but damn if I can remember the name.
Ex wife refused to let them euthanize, after weeks, he eventually regained some function, learning to walk again.
Eta: Granulomatous Meningoencephalitis (GME)
That was the diagnosis.
This post was edited on 9/5 at 8:36 am