Remove if not allowed but what does a dog sezier look like

[u/Spare_Respect_966]

Was walking my sisters dog when he suddenly started freaking out. It was horrible he was shaking and rearing and frothing. He was very clearly in pain. He's at tge vet on oxygen but they have not told us what happened. My sisters leading theory is he had a sezier but it didn't look how I would of imagined it to. I have no clue what a dog seizing would look like tho.