When should a dog be taken to emergency vet for what looks like a vestibular episode?

peaches Asked: When should a dog be taken to emergency vet for what looks like a vestibular episode?

I have a 13yr old lab/great pyr cross.He just had an episode of something that looked like a seizure or vestibular issue.He became terrified, ran to me, started panting, then collappsed and was doing supermans.He was slobbering everywhere and couldn't hold himself upright or keep steady.He came out of it just enough to run down the stairs.He was very anxious.He was decent enough for about 30 seconds to go outside with me and pee however his limbs were still trembling then he collapsed in the street and its pouring right now, the water is running like 4" deep and he couldn't get up.He was trying to crawl but he couldn't get up.I tried to be his legs for him cause hes way to big to carry and he could not walk in a straight line or hold himself upright.All this was about 15 minutes and now he has snapped out of it.Was he trying to go outside and die or something?He kept wanting to get outside and when he was out there he didn't want to come back and he was pulling me but it was like he didn't know where he wanted to go, just that he really wanted to be outside.He was really anxious. ???Do you think he needs the emergency vet.I was gonna take him but he snapped out of it before I was finished writing the address down.