The most common causes of sickness, and sometimes death, for neonatal puppies
are hypothermia, dehydration, and hypoglycemia. Hypothermia. Neonates cannot control their body temperature well during the first 4 weeks of life and are dependent upon staying close to the dam, huddling with littermates or an environmental heat for warmth. Immediate environmental temperature of orphans should be 84 to 90 degrees F during the first week and 79 to 84 degrees F during the second week. Immediate environmental temperature of litters should be 75 to 81 degrees F during the first week. Their shivering reflex does not develop until 6 to 8 days old. Therefore, orphaned neonates are highly susceptible to hypothermia, and with a fall in body temperature and decreased ability to suckle or cry, circulatory failure and death may result.
Dehydration. Body water content of neonates is 8 percent at birth and their water requirement is 60 to 100 ml (cc) per pound of body weight per day. If the pup has not nursed or received a milk substitute within hours of birth, dehydration becomes apparent within 12 to 18 hours. Again, circulatory failure and death may result from dehydration.
Hypoglycemia. Neonates should receive colostrum from the dam within 12 to 16 hours of birth. Commercial milk replacers with a similar composition to bitch's milk and those that have been tested in puppies should be fed to orphaned puppies. Most milk replacers contain 1 kcal/ml (cc) and most neonates require 24 kcal/100 g of body weight per day.
Other possible illnesses in orphan puppies can include: pneumonia, early placental insufficiency, induced hypothermia, infectious diseases, drug toxicity, congenital abnormalities, abnormally low birth weights, traumatic insults during or after the birth process, parasites, placental infections, neonatal isoerythrolysis and undetermined causes.