Are there other symptoms that you are aware of? Has your dog been outside too long in the heat? Was your dog running hard for too long? Is your dog eating and drinking? Are they drinking excessively? Is your dog showing signs of pain? If you’re dog was outside today, he may be showing signs of heat exhaustion. If that is the case, keep him calm and inside in air conditioning. Do not let him stress or exert himself for some time- make sure he drinks water. If there is no improvement, a call to the vet is warranted. If your dog was not outside in this hot weather, then I would call the vet right away as it could be something serious. I hope everything is ok.????????