sluggishness unresponsiveness appearing disorientated bright red gums, tongue, and/or eyes excessive panting high body temperature noisy breathing (this may indicate an upper airway obstruction) rapid heart rate irregular heart beat muscle tremors wobbly, uncoordinated movement Extreme signs of overheating include vomiting, which could eventually lead to collapse, seizure, or coma.
If your dog shows any signs of overheating, treat them as an emergency. Call your veterinarian immediately. Keep your dog cool with wet towels, cool water from a hose, or ice chips to chew, until you can get him to the vet. Be sure not to place ice on your dog's body, however, as this can actually hurt his skin.