Yes, pedialyte given orally can help with dehydration as it will replenish both water and electrolytes. Even something like Gatorade can be given as it will have a lot of the same benefits.
The best rehydration is IV fluids, next is fluids under the skin (subcutaneously) and then oral. The best therapy, of course, is treating the underlying disease.
I hope this helps, best of luck.
yeah you can put it in the water.
Why do you think your cat is so dehydrated?
Ok, well I would be more inclined to just let him drink plain water and warm up some canned food or baby food to entice him to eat. The plain water will correct his water deficit and the food/ pedialyte will help with his electrolyte imbalance.
If he's really that lethargic in the morning then I'd get him looked at by a vet to see what's going on and to see if he needs more specific therapy.
You should only need to give the pedialyte every 4-6 hours and just do it until he is eating on his own. It's only a temporary transition from not eating to getting back on food- it's not meant to be a sole nutrition for any period of time.
What did your vet find out today?