Shelter workers say they first noticed the dogs exhibiting signs of parvo last Monday. They say the dogs were lethargic, vomiting and had bloody diarrhea. Because parvo is a viral disease that transfers through the feces, it soon became widespread throughout the shelter. Kennel workers say the disease began to attack the lining of the dogs' digestive tracks. Now, while the shelter is shut down, workers are doing whatever necessary to prevent further contamination. Veterinarians say its important to prevent parvo and other life threatening diseases by getting your puppies vaccinated beginning at six to eight weeks of age.