[1] Death usually occurs within the first five days of life,[2] but can happen up to ten weeks of age.
[1] Like other species of mammals, canine puppies are very vulnerable during their first weeks of life, partly because they have no ability to regulate their own body temperature[5] and their immune systems are not yet fully developed.
[1] During their first few weeks of life, puppies are unable to regulate their own body temperature, and require a source of heat to stay warm.
Due to their lack of an independent immune system, strict hygiene is beneficial, as is examining the mother for disease, such as mastitis or metritis, and viral infections such as Canine parvovirus or adenovirus.
If the puppy is unable to nurse independently, supplemental colostrum replacement may help, as well as antibiotics in the case of bacterial sepsis.