The neonatal development can be divide into specific time periods; the neonatal period (birth - 2 weeks); the transitional
period (2-4 weeks); the socialization period (4 -12 weeks), and the juvenile period (12 weeks - puberty). During the late
socialization period and juvenile period, most puppies and kittens are growing versions of the adult.
The goal of neonatal care is to maximize the health and well being of the newborn puppy and kitten. The canine and feline
neonates differ from the adult counterpart in numerous ways. Determining the normal from an abnormal physical, physiological
and/or diagnostic findings is essential in enhancing the survival of the sick or marginal youngster. I always recommend the
mother and entire litter be examined. Occasionally a "house call" is in order to decrease the stress, environmental impact,
and infectious diseases exposure than can occur with a routine hospital visit. Clinical evaluation of puppies and kittens
starts with a complete case history. Information including breed, age in days, and parturition history plus the owner's concerns
are essential to the case management. After obtaining the history a comprehensive physical examination should be conducted
on a warmed surface. I perform the Physical examination in the same order as on the adult with a couple of exceptions.
General condition: A physical examination starts with observing the animal's body general condition, body movements, mentation,
posture, locomotion, and breathing patterns before handling the neonate.
Birth weight: Weigh the neonate on a warm gram scale. Birth weight is the single most important predictor of neonatal survival. Toy breeds
100 – 200 g, Large breeds 400 – 500 g, and Giant breeds 700 g. Healthy kittens should weigh 100 g ± 10 g. Low birth weights
are associated with poor performance, morbidity, mortality and congenital defects. As small birth weight puppies and kittens
are often physiologically dysmature, those neonates that are < 25% of the litter average weight, are at high risk for hypoglycemia,
hypothermia, hypoxia, bacterial septicemia and pneumonia. A deficiency in some growth factor, an endocrinopathy, poor maternal
nutrition, small placental size (uterine crowding), and inheritable and congenital anomalies have all been incriminated causes
for the lowered birth weights. Even if these "runts" make it through the critical first 2 week period, they may be chronic "poor doers" and may still die at a young age. Close observation and careful monitoring are paramount to their
survival chances. Surprisingly some of these small fries actually catch up to their littermates.
Monitoring weight gain is a good indicator of health status. Reported criteria for adequate weight gain have been reported during the neonatal
period include; nursing puppies should double their weight in 10 days; the puppies should gain 5-10%/day; and puppies should gain 2 g/kg of the expected
adult weight/day. Nursing kittens should also double their weight in 10 days; normal kittens gain 10 - 15 g/day; and the kittens should weigh 1 pound/month
for the first 4 months. Formula fed neonates grow at significantly slower rate despite the identical caloric intake doubling
their weight in 14 days.
Thermoregulation: An accurate rectal temperature in neonates requires a digital thermometer that reads to 95°F. Thermoregulation is problematic
in the neonate. The shivering reflex and peripheral vasoconstriction response are not fully developed until at least 1 week.
Their relatively large body surface area of non-cornified skin, plus the lack of insulating fat, promotes rapid heat loss
by conduction, convection, radiation, and evaporation. The vulnerable young must relay on the ambient temperature, the dam's
mothering instincts, and littermates for warmth. Environmental temperature exposure can be critical as a healthy newborn can
only maintain a body temperature 12° > than that of the surrounding environment.