The normal body temperature for a dog is in the range of 100° to 102.5°. Increases in the body temperature of a dog can be caused by environmental factors, exercise, excitement, or disease.
Dogs regulate their body temperature by panting, which forces air over moist membranes thus cooling by evaporation. This system is relatively easy to overwhelm in the presence of high ambient temperatures, particularly when combined with high humidity. These conditions lead to sever and life-threatening rises in body temperature. If the body temperature exceeds 108°, then heatstroke occurs. The consequences of this condition include interference with normal cell metabolism.
Fever caused by infection, cancer, or inflammation involve a change in the thermoregulatory set point in the brain. The rise in body temperature is usually well below a level that would be considered dangerous, but still indicates a disease causing agent. It should be noted that fever is thought to be beneficial in some cases since the body's natural processes of fighting disease may be enhanced by a moderate increase in body temperature.