Lift the skin between the shoulder blades and release: well-hydrated skin flattens instantly, while dehydrated skin returns slowly or stays tented.
Treat it as a rough screen: fat pads in obese cats can fake a fast return, and loose senior skin can fake a slow one, so combine it with other signs.
Check alongside dry tacky gums, sunken eyes, and dullness; several abnormal signs together make dehydration much more likely.
Suspected moderate or severe dehydration needs prompt veterinary fluids, especially in vomiting kittens who decline fast; do not substitute force-feeding water at home.
