Canine Distemper is history’s biggest killer of dogs. It is often the most misunderstood disease because it is often wrongly thought to be related to the disposition or “temperament” of the dog. Distemper has nothing to do with disposition or temperament. It is a viral disease that is in the same group of viruses that causes measles and mumps in humans. It is a highly contagious air borne disease among dogs, raccoons, fox, wolves, ferrets, plus other wild animals. It affects the upper respiratory, gastro-intestinal, and nervous systems, and is often fatal, especially if seizures occur. Young dogs and older dogs are most susceptible as are any dogs whose immune system is run-down fighting an illness or injury. Of course, an unvaccinated dog is mostly at risk, and many unvaccinated dogs are being rescued from flooded areas in the south. This opens up other areas throughout the USA to exposure. Vaccination is the best protection. It used to be thought that a blood test known as a titer could be run to check the level of antibodies the dog has against this and other dreaded diseases, but recent research has shown that a titer does not indicate the level of immunity to these diseases. It only indicates previous exposure or vaccination. For a titer to be really helpful it would require a test for “cell-mediated” cells, also known as “memory” cells, to determine the current level of immunity. Unfortunately, we do not have a test for these cells yet. These “memory” cells are the cells that pump out more antibodies against a disease if the immune system is challenged by the dog being exposed to the disease. Consequently, the only way to ensure proper immunity is to vaccinate. With the newer vaccines available to veterinarians, the recommendations today is to vaccinate every 3rd year against viral diseases such as Distemper, Parvo, Parainfluenza, Hepatitis, and Rabies. For bacterial diseases such as Leptospirosis, Bordetella, and Lyme, it is still recommended to vaccinate yearly.