Immunization – the activity of resisting the body to disease-causing bacteria and viruses.
In simple words, immunity is the resistance of the body to deleterious agents such as disease-causing bacteria and viruses.
Passive Immunity:
Immunity that the foetus gets from the mother is known so as it provides protection against various infections when the pup enters a hostile external environment on coming out of the uterus. Immunity is provided by antibodies (protein in nature) produced in response to stimulation by an antigen. Bacteria, viruses or their vaccines act as antigens and lead to the production of antibodies which protect the body against disease.
Without maternal immunity, many foetuses may not survive. Maternal immunity, however, interferes with the response to the vaccination with which we try to give active immunity to dogs. The maternal immunity level gradually goes down with the maturity of the pup.
The first milk colostrums of the mother contain antibodies. Depending upon the quantity of colostrums taken by the pup, plus other factors, the amount of the antibodies even amongst pups of the same litter varies greatly.
Active Immunity:
The most successful and ideal approach to immunization or vaccination of dogs with unknown amounts of maternal antibodies is based on multiple vaccinations. The last immunization should be given at about 22 weeks of age when almost all pups no longer have sufficient levels of maternal antibodies that could interfere with external vaccination.
It is important to note this fairly new and useful information about the number of days up to which the maternal antibody level for canine parvo virus may remain in the body, and which could negatively affect proper immunization. If the last multiple vaccination in the necessary series is given when the pups are 20 or 22 weeks of age, most pups can be effectively immunized. Many of the previous puppy immunization schedules recommended the last immunization of the series to be given at 12 to 14 weeks of age.
Various immunization schedules have been recommended, suggesting appropriate ages for the first vaccination and repeats thereafter. In general, the more repeat vaccinations against each disease that a puppy receives up to about 4 months of age, with an interval of about 2 to 3 weeks, the more likely it is that he will attain immunity at the earliest possible age with less likelihood of being susceptible to infections.