Is my dog having a seizure?

my dog is very lifeless, she hasnt been eating at all for the past day but drinking a lot of water. she is drolling a lot from the mouth and cant walk straight. she wont even get up and try to walk today, she is breathing heavly and just laying around, if this is a seizure what should you do with your dog. Also could some type of poisen cause a dog to have seizures?