CRITICAL: FROTHING MOUTH AND SEIZURE IN MY DOG

My dog suddenly started going through a terrible seizure. He's with saliva coming out of his mouth and can't stand up. I don't know what to do. Please help! Is this something I should call a vet about immediately? I'm so scared, he's my best friend. My Dog Is Having a Seizure, Foaming at the Mouth It's incredibly frightening to witness your dog