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Canine Parvovirus


Vaccinations, starting by 8 weeks of age, will prevent most (but not all) cases of parvovirus infection. During the first weeks of life, puppies are protected by high levels of maternal antibodies. As these levels decline, there is a period lasting from two to four weeks during which puppies are susceptible to infection because vaccinations have not yet fully taken effect. This susceptible period varies from pup to pup, which is why pups anywhere between 6 and 20 weeks age can be especially susceptible to parvo. Nearly all apparent vaccination failures are due to exposure during this susceptible period.

Newer high titer-low passage vaccines are narrowing the window of susceptibility. These modified live virus vaccines contain a higher number of virus particles (high titer), which are less attenuated (low passage; a low passage vaccine contains virus particles that have been less attenuated, or weakened, than those in the average vaccine). That means high titer-low passage vaccines can generally elicit an immune system response in young animals who have a maternal antibody level that would normally prevent them from responding.

Nevertheless, it is still important to isolate young puppies as much as possible from other dogs and from potential sources of infection until they complete the parvo vaccination series at 16 weeks of age.

Currently, recommendations are for a booster a year from the initial vaccine series and then revaccination every three years.

WebMD Veterinary Reference from "Dog Owner's Home Veterinary Handbook"


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