parvo is a disease that attacks their digestive systems. Dogs that over the age of 1 year are normally immune to it if they have all their shots. The dog will start throwing up and have a loss of appetite and lack of energy. Normally it stays dormant for 3 to 7 days then they will start showing signs of it. It is highly contagious disease that is normally spread through the fecies of dogs. It is most common in dobermans, labs and rotweillers.