The best way to treat a dog with a fever above 103 degrees Fahrenheit is to call a veterinarian. If the fever reaches above 105 F, WebMD recommends lowering the body temperature by applying cool water to the dog's coat, focusing on the ears and feet while monitoring its rectal temperature. If this is not sufficient, use a fan on the damp fur. Seek veterinary help quickly to determine cause.
The normal body temperature for dogs is between 101 F and 102.5 F. Fevers may be caused by infections or toxins. Additionally temperature may rise due to exertion or sometimes just exposure in hot or humid weather. This is referred to as hyperthermia or heat stroke. A low-grade fever is also common for 24 to 48 hours after vaccination.
Fevers of unknown origin are attributed to more serious underlying causes such as cancer, bone marrow problems and disorders of the immune system. Other symptoms that indicate illness in a dog are lethargy, shivering, depression, loss of appetite, vomiting and nasal discharge. While conventional wisdom recommends feeling a dog's nose to check for a fever, the only accurate way to gauge a dog's temperature is with a rectal thermometer specifically designed for use on dogs.