I don't know if either of you saw the comments, but I thought this was interesting:
Mark Miller · President (title) at My own business
http://iheartdogs.com/you-must-read-this-before-letting.../
This happened to my dog, 15lb shih-tzu, he loves swimming but eats at the bubbles on the surface of the water
After a day of swimming he started to throw up, moaning of stomach pains, laying on the couch not moving, I noticed his saliva kept coming out of his mouth I knew right away he was very ill, I googled the condition and then ran to the store for Gatorade, I gave him about 4 cap full of Gatorade, after abou t 20mins he started feeling much better, I then got a bottle of Pedialyte, gave him about 3 cap fulls of that and of course I had to force feed it to him pouring it in his mouth. After an hour he was feeling much better, probably saved his life. Dog swimmers keep a bottle of Pedialyte on hand, this will get electrolytes back in your dog quickly, a cap full of Gatorade could be helpful but not recommended. By acting quickly I saved my dogs life. Pool owners, keep Pedialyte on hand and don't let your dog swim too long, if your dog takes a break, give him a cap full of Pedialyte in between breaks and most important when you see your dog has constant saliva coming from his mouth it's a huge red flag and get electrolytes in him/her asap. Be careful and smart with your swimming dog.
I would still get the dog to the vet, but having the Pedialyte might be helpful in the meantime. I should note this same person posted separate comments that mentioned giving Powerade, "Actually it was Powerade that states replenish 4 electrolytes, has sodium, potassium, calcium, magnesium. It could have been the combo of Powerade and Pedialyte that made him better?? I read Gatorade, Powerade is not recommended due to the sugar and other stuff but a few cap fulls won't hurt and adding the Pedialyte was the best for my dog, again by acting quickly and watching the signs for water intoxication will save your dogs life."