| Yes, it is necessary. The following was taken directly from the American Veterinary Medical Association (AVMA) website:
Canine Distemper
General Information
Canine distemper virus may occur wherever there are dogs. It is the greatest single disease threat to the world's dog population.
Younger dogs and puppies are the most susceptible to infection. Among puppies, the death rate from distemper often reaches 80%. The disease also strikes older dogs, although much less frequently.
Even if a dog does not die from the disease, its health may be permanently impaired. A bout with canine distemper can leave a dog's nervous system irreparably damaged, along with its sense of smell, hearing or sight. Partial or total paralysis is not uncommon, and other diseases — particularly pneumonia — frequently strike dogs already weakened by a distemper infection.
Cats are not susceptible to canine distemper. The so-called "cat distemper" is a different disease caused by a different virus. Neither disease is transmissible to humans.
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What Does Distemper Do?
Canine distemper is a highly contagious disease caused by a virus.
Canine distemper virus is most often transmitted through contact with respiratory secretions. Contact with the urine and fecal material of infected dogs can also result in infection.
The many signs of distemper are not always typical. For this reason, treatment may be delayed or neglected. The disease frequently brings about something like a severe cold. Most infected dogs have a fever and "stuffed up" head. Exposed animals may develop bronchitis, pneumonia and severe inflammation of the stomach and intestines.
The first signs of distemper an owner might notice are squinting, congestion of the eyes, and a discharge of pus from the eyes. Weight loss, coughing, vomiting, nasal discharge, and diarrhea are common. In later stages the virus frequently attacks the nervous system, bringing about partial or complete paralysis as well as "fits" or twitching. Dogs suffering from the disease are usually listless and have poor appetites.
Sometimes the signs may be very mild and perhaps go unrecognized, or the dog may have a slight fever for a couple of weeks. If pneumonia, intestinal inflammation or other problems develop, recovery takes much longer. Nervous problems often last many weeks after the animal has recovered from all other signs of infection. Occasionally the virus causes rapid growth of the tough keratin cells on the footpad, resulting in a hardened pad.
Distemper is so prevalent and the signs so varied that any sick young dog should be taken to a veterinarian for a definite diagnosis.
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Prevention and Protection
Dogs that survive a natural infection usually develop sufficient immunity to protect them from distemper the rest of their lives. Many dogs — particularly pups — do not survive a naturally-acquired infection. The safest protection is vaccination.
Puppies born to dogs which are immune to distemper acquire a degree of natural immunity from nursing. This immunity is acquired through substances in the colostrum, which is the milk produced by the mother the first few days after giving birth. The degree of protection a pup receives varies in proportion to the amount of antibody its mother has, but the protection diminishes rapidly.
Your veterinarian can determine the most advantageous time to begin vaccination based upon his or her experience and the general health of your dog. Ask your veterinarian about a recommended vaccination schedule. | 
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