Summarize the following:
In most situations, fever is nothing to worry about. It's a good indicator that the body is fighting back an infection or is undergoing repairs. In some situations, however, fever can be the sign of a bacterial infection. If your dog is displaying any abnormal symptoms, contact your vet immediately. When bacterial infections with gram negative bacteria are present, they release toxins from their cell walls that act as signals to the brain to cause fever. In these cases severe bacterial infection can lead to even more severe fever with a very high temperature. This extreme temperature, instead of helping the animal can lead to damages to sensitive organs, like the testicles and the brain. When this happens, convulsions and coma, and sometimes sterility, can result. Thus it is very important that a fever be detected earlier, and a prompt veterinary therapy be given to prevent these unwanted effects. When in doubt, contact your vet for a professional opinion. In addition to seeking medical treatment if abnormal symptoms are present, it's a good idea to take this fever seriously if it lasts for more than 24 hours, too. Your vet can prescribe an anti-pyretic (anti-fever) medication to bring his temperature down almost immediately. If your dog's fever is related to another, often more serious, condition, you'll notice another set of symptoms entirely. It could be a more serious respiratory or gastro-intestinal infection. Be on the lookout for the following:  If he has a respiratory infection he may cough, sneeze, and have a runny nose or streaming eyes. This will likely impede his normally rambunctious behavior and sleep patterns, too. If he has gastro-intestinal infection or inflammation, then he may be anorexic, vomit or have diarrhea. If you suspect he has a gastro-intestinal disturbance, follow him outside when he toilets so that you can see what he passes. Does he have diarrhea? Is there blood in his urine? If you notice anything abnormal related to either condition, consult your vet immediately. There is likely an infection present; fever is just one of many symptoms present that need to be addressed.

Summary:
Know that fever is a normal immune response. Call the vet. Consider other related physical ailments.