DETERMINING IMMUNITY
Titre Testing and the quest for the most highly-sought answer
With apologies to Shakespeare, “To vaccinate or not to vaccinate, that is the question.”
And for parvo virus and distemper in dogs, Titre Testing is the answer. Or at least, when we are able to determine the immune status of the dog,
then deciding whether or not to vaccinate is much easier.
The microscopic world is one of intense competition for resources. Trillions of bacteria are trying to penetrate the body, in order to eat the precious
nutrients it contains. Opportunistic viruses are ready to take over our cellular replication processes, to create even more viruses. (That is really all
they want from us – but they happen to make us really sick in the process.)
Fortunately for us, as well as for our pets, we have a very sophisticated set of cells ready to take on the role of sentinel. These sentinel cells are
able to neutralize invading microbes. This set of cells is known as the immune system.
When a microbe invades the body, the first line of defence the immune system mounts is an attack, eating some of the invading microbes and destroying
others. During this process, the immune system cells “read the bar code” of the invading microbe. The “bar code” of the microbe allows the
immune cells to deploy specific tactics to destroy the invading microbe. Then the second line of immune cell defence comes along, armed with specific
information about the invading microbes and how to neutralize them.
The immune system has a memory that contains a record of past encounters with all sorts of microbes. That memory is maintained in cells and in
free-circulating chemicals known as immunoglobulins. Thus, when a specific microbe penetrates the body for a second time, the immune system quickly
retrieves the information on how to neutralize that microbe. In this way, the animal is effectively resistant to the infection.
Immune defence information persists for a variable length of time, depending on the particular microbe, the health of the animal, and environmental
conditions present. For example, immunity to Kennel Cough (a sore throat in dogs) last for a maximum of one year. For the parvo and distemper viruses
that affect dogs, immune memory may be retained for three to five years.
A dog that is resistant to parvo or distemper, and is re-exposed to the viruses, will have its immune memory reinforced; this reminder prolongs the
immunity. If the animal does not have contact with the virus for several years, eventually the immune system loses the information regarding how to
neutralize the virus, thus leaving the animal susceptible once again. Also, an animal with a weak immune system may not be able to retain immune memory
for very long.
By means of the Titre Test, we are able to detect and measure the immune memory. This test measures the levels of immunoglobulin present to fight
against a given microbe. An animal with high levels of immunoglobulin for a specific virus is resistant to that virus, and vaccination against that
virus is therefore unnecessary.
However, as indicated above, immunoglobulins are just one part of the immune mechanism response. An animal may have low immunoglobulin levels for a
particular virus and still be immune, because other immune mechanisms are very active. However, if an animal has high levels of immunoglobulins, we
know for certain that it has immunity to the virus. Titre testing allows us to avoid unnecessary vaccinations, by means of a rational and objective
method.
Unfortunately, there is nothing similar available for cats; they must go their ways without.
return to top of page
