Titers for parvo and distemper are obtained using a blood test to measure immunity. While titers are an excellent way to determine if your dog has immunity against distemper and parvo, some might argue that neither repeat vaccine administration nor canine parvo and distemper titers are necessary if your dog was properly vaccinated in the past. Some people claim that a titer level is merely a ‘snapshot in time’ of what is happening in the body. That just isn’t correct. Research shows that 90 to 98% of dogs who have been properly vaccinated, have measurable titers to these viruses and are protected against the diseases for many years. The only time titers might be expected to drop off suddenly is in an animal whose immune system is suppressed by disease (eg, cancer) or drugs. Keep in mind, however, that an immunosuppressed dog is not a candidate for vaccine administration, as vaccines can further compromise the immune system.

While some veterinarians challenge the validity of basing decisions on the results of titers, this concern is not justified. Dr. Ronald Schultz, noted animal vaccine expert, puts it this way. Parvo and distemper vaccine titer tests “show that an animal with a positive titer test has sterilizing immunity and should be protected from infection. If that animal were vaccinated it would NOT RESPOND with a significant increase in antibody titer, but may develop a hypersensitivity to vaccine components. Furthermore, the animal doesn’t need to be revaccinated and should not be revaccinated since the vaccine could cause an adverse reaction. You should avoid vaccinating animals that are already protected.”

A dog has immunity to these diseases as long as any measurable titer is detected. Dogs with negative or zero titers are not protected against canine parvovirus and likely not protected against canine distemper virus. Moreover, dogs with no measurable titer to canine distemper following vaccine administration may have an inheritable trait making them non or low responders; these dogs should not be used for breeding.

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