Parvovirus is caused by a virus and is a highly contagious disease which can be fatal. It is spread by healthy dogs sniffing the excrement of an infected dog which causes serious inflammation of the intestines. Within a very short time the dog will become critically ill with a temperature, vomiting of blood, bloody diarrhoea, and drowsiness. Some dogs die of dehydration because they refuse to eat and drink. Large amounts of fluids are given by infusion but most dogs die within 48 hours of the first symptoms appearing. Puppies are vaccinated while still in the litter as the infection can cause heart failure.