A recombinant distemper vaccine is now available and, ideally, dogs will receive either an MLV or a recombinant version of distemper vaccine.
The first distemper shot should be given shortly after weaning and before a puppy is placed in his new home and is exposed to other dogs. Some veterinarians recommend vaccinating puppies at 5 to 6 weeks of age, using a combination canine distemper-measles-parainfluenza vaccine. The rationale for combining distemper and measles vaccines is that a high percentage of 6-week-old puppies do not get a satisfactory response from the distemper vac- cine alone because of maternal antibodies that neutralize the distemper antigen. The measles virus, which is quite similar to the distemper virus, can overcome maternal antibody interference and induce partial distemper protection. Alternatively, if maternal antibodies have actually disappeared in the 6-week-old puppy, the distemper portion of the vaccine will induce complete protection.
The distemper-measles vaccine should be used only once, for the first vaccination, and only in puppies. The newer recombinant distemper vaccine seems to overcome maternal antibodies and is now believed to be a better option than the distemper-measles combination.
Postvaccination encephalitis has occasionally occurred when an MLV distemper vaccine has been used in combination with a parvovirus vaccine in pups younger than 6 to 8 weeks of age. Therefore, parvovirus vaccine should not be given along with the first distemper vaccination in very young puppies. The recombinant distemper vaccine is unlikely to cause encephalitis, and is therefore recommended for young puppies.
Puppies younger than 8 to 9 weeks of age should be revaccinated every four weeks until they are 16 weeks of age. Current recommendations are to revaccinate at 1 year of age or in a year from the last vaccination, and then every three years. This time period may be extended with future research data on duration of immunity.