This tiny virus is an important cause of enteritis, myocarditis, and diarrhea in neonates and young dogs. In neonatal animals, myocarditis may occur with no enteric signs. Two types of canine parvovirus exist. The former tends not to cause clinical illness in dogs, however one recent study implicated the CPV-1 strain as the causative agent in the neonatal death of puppies. Generally the CPV-2 strain is implicated in disease and clinical signs.
Infection is by the fecal-oral route caused by the ingestion of fecal contaminated material.
The virus requires cells with a high nuclear and cytosolic activity in order to replicate effectively, thus only cells actively dividing are affected . Once inside the oral cavity, the virus infects white blood cells residing in the tonsils, thymus and any mucosal associated lymphoid tissue. In the myocardial form of the disease, virus can also infect neonatal myocardial cells that are actively dividing. These sites are the primary sites of virus replication . Additional virus can move down the gastrointestinal tract and infect white blood cells associated with the mesenteric lymphnodes, or Payer s Patches of the ileum.