Often panting is a sign of pain as well as heat. If the dog is acting really unusual then I'd say yes go to the vet and see if something can be found.
They often pant if their stomach hurts, if a hip or spine hurts, if they have a bad tooth etc.
Could even be heart discomfort.
I'd say your dog is probably in distress and should see the vet.
Hope this helps you!
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