Plain pedialyte works great for dogs who are dehydrated, have diarrhea or are vomiting. It is safe to use.
There are no comparable products, aside from IV fluids.
Let me know if you still have questions.
I'm not sure why there is not a pet specific product for this.
The standard formula is fine for dogs. You can even make your own at home with the following recipe:
4 Tablespoons Sugar3/4 Teaspoon Salt1 Teaspoon Bicarbonate of Soda1 Cup Orange Juice2 Pints Water