Hello I am Dr. Joey. Thanks for trusting me to help you and your pet today. I am a licensed veterinarian with over 15 years of experience. I look forward to working with you.
It sounds like you are worried about heat stroke (or heat prostration)? This is certainly a concern. I am not sure which part of the country you live in but assuming it was several hours ago when this occurred, then it is possible she overheated but if she had serious heat stroke then she would've had terrible symptoms which can range from vomiting, diarrhea, dehydration, and depression. As heat stroke progresses, severe respiratory distress, cyanosis, petechial hemorrhages, collapse, seizures, cerebellar signs, oliguria, bloody diarrhea, and vomiting blood may develop. The previously elevated body temperature may then decrease to subnormal, and neurological signs (seizures or coma) often precede death. The problem in heat stroke is that a dog's body temperature goes too high (over 105F) and this causes damage to other organs (brain, liver, kidneys, etc). The only way dogs can get rid of heat is to pant it off.
So, probably not stroke unless you see any of those signs. But heat stress is certainly possible. I must recommend you get her in to be examined by her veterinarian when they open this morning. In the meantime, keep her water available. You can also take her temperature and if elevated (over 103.5F) then this may be an emergency and you need to have her seen now. Also if she has any of those symptoms have her seen now.
Please let me know what questions you have at this point. I've thrown a lot of information your way. If you have all the information you need, then please do not forget to submit a rating as you exit.