Parvo spreads through direct contact with infected dogs or contaminated feces, and the virus can survive in soil and on surfaces for months to years. Puppies between six weeks and six months old are most vulnerable because maternal antibodies wane before the vaccine series is complete. Treatment involves intensive hospitalization with IV fluids, anti-nausea medication, antibiotics for secondary infections, and nutritional support. Survival rates improve significantly with early, aggressive care. Vaccination is the single most effective prevention: puppies receive a series of shots starting at six to eight weeks old, with boosters every three to four weeks until sixteen weeks of age.