When a cat is dehydrated, they need fluids to help rehydrate them. This can be done by offering them water or an electrolyte solution like pedialyte. If your cat is not drinking on their own, you may need to syringe feed them the fluids. Your vet can show you how to do this properly. Dehydration can be dangerous for cats so it is important to seek veterinary care if your cat is showing signs of dehydration.