Dog Owner's Home Veterinary Handbook.pdf - Mr. Walnuts

to make them less infectious) pathogens rendered incapable of causing disease,
or toxins and pathogen products that will also stimulate a response by
the dog’s immune system. As with natural exposure, vaccination stimulates
the production of antibodies that are specific for the particular pathogen in
the vaccine. However, unlike natural exposure, the duration of protection
may be limited. Accordingly, to maintain high levels of protection, booster
vaccines are recommended. How frequently a dog will need boosters depends
on the antigen used, number of exposures to the pathogens, the dog’s own
immune response, and the type of vaccination used. Vaccination schedules
need to be customized for each individual dog.
Vaccinations may not be successful in all dogs. Rundown, malnourished,
debilitated dogs may not be capable of responding to a disease challenge by
developing antibodies or building immunity. Such dogs should not be vaccinated
at that time, but should be vaccinated when they’re in better health.
Immunosuppressive drugs, such as cortisone and chemotherapy agents, depress
the immune system and also prevent the body from making antibodies.
Another type of immunity is called passive. Passive immunity is passed
from one animal to another. The classic example is the antibodies newborn
pups absorb from the colostrum of their mother. Puppies are best able to absorb
antibodies from their mother’s milk during the first 24 hours of life. The
immunity persists only as long as the antibodies remain in the puppies’ circulation.
The duration of immunity depends on the concentration of antibodies
in maternal milk when the pups were born. Dams vaccinated just before they
were bred have the highest antibody levels and are capable of protecting puppies
for up to 16 weeks. However, some veterinarians believe this additional
booster is unnecessary.
Puppies younger than 3 weeks old may be incapable of developing antibodies
in response to vaccination because of physical immaturity or interference
by passive maternally acquired antibodies. Maternal antibodies can bind the
antigen in the vaccine and keep it from stimulating the immune system. These
passive antibodies disappear at between 6 and 16 weeks of age. Therefore,
when vaccinating very young puppies, the vaccine must be given more frequently
to ensure that the vaccine will stimulate immunity as soon as maternal
antibody levels decline and can no longer interfere with the vaccine.
Another source of passive immunity can occur with a transfusion of blood
products with antibodies into a dog with a serious infection or immune problem.
This is not done frequently, but can be a life-saver for some dogs.
Vaccinations
INFECTIOUS DISEASES • 91
There are several types of vaccines currently available for use in dogs: modified
live virus (MLV), inactivated or killed virus, and the newest recombinant
technologies—live vectored, subunit, and DNA vaccines. Modified live virus