When a dog is overheated, the body’s cooling mechanism will activate to increase bodily temperature until it finds a new equilibrium. This can take up to three hours or even longer in very hot weather conditions. During this period of time, panting may become more evident — especially on hot days when temperatures are high enough for sweating to occur. It is important not only that the animal has access to plenty of water, but also that it be allowed some time out of direct sunlight and away from other pets so it can rest and cool itself down. If your pet does begin sweating profusely after being exposed to extreme heat (over 90 degrees Farenheit), contact your veterinarian promptly since there could be an underlying medical problem causing the excessive perspiration or dehydration if no cause is found.