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

92 •DOG OWNER’S HOME VETERINARY HANDBOOK
vaccines are vaccines that contain virus that is alive and will replicate when
in a dog, but has been modified so that it shouldn’t cause the actual disease.
These vaccines tend to generate a quick and full immune response. Killed
virus vaccines are vaccines with dead virus, which will not replicate in a dog,
so they are incapable of causing disease. Instead, they rely on surface antigens,
along with immune stimulants called adjuvants, to stimulate an immune
response.
Modified live vaccines are more effective and produce longer-lasting
immunity than do killed vaccines. Results for recombinant vaccines indicate
that immunity can last as long as MLVs. With all types of vaccines, booster
shots are necessary to maintain an adequate level of protection. The frequency
of needed boosters shots is very variable, and depends on the disease
involved, the individual vaccine, the dog’s own immune system, and whether
he has been exposed to the disease agent naturally.
Recombinant vaccines are among the newest products in the rapidly
emerging biotechnology market. The technology relies on the ability to splice
gene-sized fragments of DNA from one organism (a virus or bacteria) and to
deliver these fragments to another organism (the dog), where they stimulate
the production of antibodies.
For the live vectored version, genes from a canine antigen may be put into
a noninfectious virus. Antibodies are stimulated; there is no replication of the
antigen. Subunit vaccines stimulate immunity to a part of the antigen of an
infectious organism. These are set up to provide the most immunity for the
least amount of antigen used. With DNA vaccines—currently experimental
for dogs—only a small amount of DNA from the infectious agent is used.
Thus, recombinant vaccines deliver specific antigen material on a cellular
level without the risk of vaccination reactions associated with giving the
entire disease-causing organism. This represents a truly new development. It
is expected that recombinant vaccines will soon replace MLVs and whole
killed vaccines for many, if not most, canine infectious diseases.
WHY VACCINES FAIL
Vaccines are highly effective in preventing certain infectious diseases in dogs,
but failures do occur. Failures can be due to improper vaccine handling and
storage, incorrect administration, inability of the dog to respond because of a
depressed immune system, or the presence of neutralizing maternal antibodies.
Stretching out the vaccine by dividing a single dose between two dogs is
another reason why a vaccine may not be effective. And if the dog is already
infected, vaccinating him will not alter the course of the disease.
Because proper handling and administration of vaccines is so essential,
vaccinations should be given by those familiar with the procedure. Anyone
giving a vaccine also needs to be ready to handle any adverse reactions. When