How Long Can A Dog Go Without Adequate Water & Food?

In the heat of the summer a dog (or any animal) will die rather quickly without shade or water.  He will live a few days without food...not so with water.  Water must be supplied daily or as the bowl becomes empty.  Recently my grandson's dog got out of the yard and was gone for only 1 hour when they found him staggering down an alleyway.  The dog had had a heat stroke.  He had been running in the heat and had no shade.  He did not die but came very close to death.