Prevent Hypothermia, Your Puppies' Worst Enemy
The most critical need of a new puppy is warmth. Usually, the newborn is protected against hypothermia because it's close to the mother and brothers. Newborn puppies can't regulate their body temperature until 12-14 days after birth. Newborns can maintain their body temperature only -13°C to -11°C above the environmental temperature. The owners must make sure that the puppies' environmental temperature be around 29°C. The physiologic reasons for this include decreased body fat, poor peripheral vasoconstrictive (any agent that causes a narrowing of an opening of a blood vessel: cold or stress or nicotine or epinephrine or norepinephrine or angiotensin or vasopressin or certain drugs; maintains or increases blood pressure) reflexes, a large surface area to body weight ratio, and lack of a shivering reflex. The shivering reflex begins when the puppies are about six to eight days old. The lack of a sufficient cardiovascular response to hypothermia apparently makes hypothermia an irreversible event in the newborn, especially if accompanied by anorexia (a prolonged disorder of eating due to loss of appetite).
Hypothermia is recognized when the core body temperature drops below 34.44°C. It may be manifested by ineffective nursing. The bitch may push the sick puppy away from the others. At first, the puppy may become more dynamic, but this activity stops as the core body temperature begins to drop. As hypothermia gets worse, the puppy becomes inactive, with very slow respiration.
One method of treatment is to slowly re-warm the puppy by holding the pup next to one's body - inside a loose garment or pocket - and by gently massaging the pup. Rapid re-warming should be avoided as this will result in an increase in metabolic rate with the possibility of increasing tissue hypoxia. Other heating devices that have been used include heating pads, lamps, and hot water bottles. Regardless which heating devise is used, care should be taken to prevent burns, as the newborn might not show pain, and the peripheral circulation may not be adequate to effectively distribute the heat. Another alternative is to use an incubator, which should not be kept below 22°C and not above 32°C, as it could lead to respiratory problems. For both the normal and hypothermic newborn, the proportional humidity within the incubator should be kept at 55% to 60%, and the concentration of oxygen should be between 30% and 40%.