In the wild, the food their ancestors ate (rodents, etc.) had a high enough water content that they didn't feel thirsty as often. (askthecatdoctor.com)
As I see my list of publications grow, I'm left feeling thirsty for more. (sciencemag.org)
Even if you don't feel thirsty after a workout, it is vital to hydrate with water, just like you would in warmer temperatures. (bostonmamas.com)