InsideBayArea.com published a helpful article on canine heat stroke.
When a hot dog is a bad thing: Heat stroke help
A dog with heat stroke? Sounds like all you need to do is let them cool down for a while. Actually, its a lot more serious than that and can be fatal. And by the time its detected, it could be too late.
Signs to look for
What is heat stroke? Its the syndrome of decline in mental status and damage to internal organs that happens when the body temperature rises too high.
A dog suffering from heatstroke will often pant rapidly, drool, vomit, and become weak or mentally un-responsive.
Body temperatures of 105-106, if sustained, have been reported to cause permanent organ damage, and if body temperature rises to 109 direct thermal damage to internal organs occurs quickly. This can begin a cascade of organ malfunctions that is fatal.
To read more, follow this link.