Could you tell me what are signs of dehydration in 1 year olds?

Dehydration: Your child is likely dehydrated if he is urinating less. If it's a lot less, you should have him seen either by his doctor or go to the emergency department because he might need some IV fluids. If he's just urinating a little less, then you'll have to increase the fluids you're giving him. Pedialyte is a good option as is water.