Please help our dog Apollo! He is very ill!

Apollo is a 3 year old border collie,  he has the best personality and such a LOVER! If you know him you know that he is an amazing and very smart dog. Earlier today he ran away and came back not acting himself. He was very weak and stiff. Within the next few minutes we noticed his eyes starting to roll back in his head and would collapse when we tried to pet him. We then rushed him immediately to the vet in Grand Rapids, he started having a very bad seizure and didn’t know if he was going to make it... they told us he had ingested some type of chemical or poisoning. Since we had no idea what he ingested we are having to rush him to the cities for further care.  Anything, even a small amount would be greatly appreciated!