CDV infects an animal through aerosol inoculation (breathing) or through ingestion. The virus contacts epithelium of the respiratory tract where it is picked up by macrophages. The virus is carried to local lymphatics – tonsils and bronchial lymph nodes. Virus numbers increase here as the virus divides. By about day 5, the virus makes its way to the spleen, lamina propria of the stomach, small intestine, mesenteric lymph nodes and the Kupffer cells of the liver. This spread induces a profound immunosuppression in the animal.
Dependent
upon the individuals
ability to
mount an immune response to the virus, several things can occur to the
dog:
1) Those animals with adequate antibodies and that are able to mount a good immune response should have cleared the virus and should show no real apparent illness. These animals also have a very low prevalence of CNS illness
2) Dogs with intermediate or low levels of immune response will likely have viral spread to the epithelial tissues by about day 10. This is the time when shedding of the virus, which can be done from any body excretion, can occur. CNS infection is possible. These signs develop after the GI and respiratory signs have been expressed. After, the dog can again recover, although his chances of doing so are now lower than in those animals with a better immune system.Those dogs that do
not recover can develop chronic neurological signs caused by
demyelination. This dogs will usually die. Other dogs may appear to
recover from the virus, which is misleading. The virus will
remain the brain, and after a period of time (often years), recurrent
neurological problems will develop, including such signs as atazia and
seizures.
The incubation period for the virus is
between 6 and 10 days. Vaccination is highly recommended as prevention
is the best cure.