Image via WikipediaThe canine parvo virus has existed for about than twenty years. It is found almost everywhere. It can be found on the floor, on the carpet, on the grounds, on the walkway, in the garden, and in every place that dogs have access to. In the soil, the parvo virus can protect itself for about seven months. It cannot be destroyed by extremely cold temperatures. Thus, the winter season simply freezes and preserves it.
The usual victims of the canine parvo virus are the puppies. The reason for this is that the puppies are still incapable of defending their bodies from the invasion of the canine parvo virus. The underdeveloped immune system of the puppy cannot produce antibodies that will destroy any foreign material that will enter the puppy's body. The survival of the puppy during this vulnerable stage will depend on the puppy's nursing.
When the puppy is being nursed by his mother, he is getting a special milk called colostrum. This milk contains antibodies produced by the immune system of the mother dog. If the mother dog has immunity against the canine parvo virus, the antibodies against this particular virus will be passed along to the nursing puppy. But the antibodies do not survive long. Every nine days, the number of these antibodies drops to half. This is why the puppies must constantly get a supply from the mother.
The puppy enters the most vulnerable phase of his life when he stops nursing and his immune system is still too young to fight the canine parvo virus. And there is good possibility that the puppy will pick up this virus when he uses his mouth to clean itself or eats food from the floor. Only a small amount of canine parvo virus is needed to begin the life-threatening infection.
Once the canine parvo virus gets inside the body, it searches the nearest organ that contains rapidly dividing cells. Usually, the dog parvo virus navigates towards the lymph nodes of the throat. Here, the virus sets up a sort of camp where it will begin to replicate itself, and make thousands of canine parvo virus.
Obviously, the lymph node is too small to accommodate all the viruses. The canine parvo viruses find the bloodstream where they can search other organs that have the same rapidly dividing cells, such as the bone marrow and the gastrointestinal tract.
Within the bone marrow, the canine parvo destroys the cells of the young immune system. As a result, there will be too few antibodies produced to fight the canine parvo viruses. In the gastrointestinal tract, the canine parvo viruses attack the Crypts of Lieberkuhn. This part of the intestine is responsible for producing the villi and microvilli, which are protrusions that facilitate the absorption of nutrients. When the Crypts of Lieberkuhn are destroyed, there will be no villi and no absorption of nutrients. The puppy suffers from nausea and diarrhea. The puppy may die because he has lost too much fluid.
Fortunately, the damage to the immune system is not as devastating as the one suffered by the intestines. Thus, antibodies can still be produced. The survival of the infected puppy will now depend on how fast can the impaired immune system produce antibodies.