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PEDIATRIC CRITICAL CARE
Ashley Davis, DVM, Diplomate ACVECC
Manager of the Emergency and Critical Care Service
Intern Director, Southfield MI BluePearl Veterinary Partners
29080 Inkster Road
Southfield, MI 48034
Neonatal and pediatric critical care is extremely different from adult critical care. Neonates are
animals between 0–2 weeks of age and pediatric animals are those < 6 months of age. Pediatrics
can further be broken down into infants (2–6 weeks of age) and juveniles (6–12 weeks of age).
The first step in approaching a neonate/pediatric patient is acknowledging how these patients
differ from adults. Physical Examination: Neonates have much higher heart rates than adult animals. A puppy typically has a heart rate of
200 bpm while kitten heart rates are typically 250 bpm. The normal respiratory rate for a
neonate is 15 bpm at birth and should increase to 30–35 bpm within 1–3 hours of birth. Their
heart rates are increased to help improve cardiac output as neonates lack the contractile fibers in
their myocardium that is typically used to increase cardiac output. It is also very important to
know that neonates/pediatric patients have lower body temperatures than adults. The normal
body temperature of a puppy is 96–97℉ the first 1–2 weeks of life and will increase to 100℉ by
4 weeks of age. Kitten temperatures are also lower at birth (98℉) and will increase to 100℉ by 1
week of age. Puppies and kittens will also have hyperemic mucous membranes until they are 4–
7 days old and their umbilical cords will fall off at approximately 3 day of age. Puppies and kittens are born with closed eyelids and ear canals. The eyelids open between 10–16
days in puppies and 5–14 days in kittens. Once the eyes open the cornea can appear colored for
2–4 weeks of life and it can take up to 4 weeks for the pupillary light reflexes to normalize and
2–3 months for a menace to develop. The external ear canals open between 12–14 days in
puppies and 6–14 days in kittens and by 2 weeks of age they will respond to sound. Functional
hearing can be tested after 3–4 weeks of age in puppies and 4–5 weeks in kittens. Testes will
descend around 4–6 weeks of age. A healthy neonate should have a strong suckle reflex and should be lively. Over the first 2–3
weeks of life they will spend nearly all their time sleeping and nursing. A crying, limp, lethargic
or muscle wasted neonate is a sick neonate. Neonates vary in birth weights based on their breed.
Most cats will weight ~100 grams while puppies will weigh between 100–700+ grams based on
their breed. It is very important to closely monitor neonatal weights as they should gain weight
readily. Kittens should gain between 7–10 grams per day and puppies should gain 1 gram per
pound of anticipated adult weight per day. If a neonate is not gaining sufficient weight a
surrogate dam could be utilized if available or bottle-feeding/tube feedings will need to be
instituted. Neonates should also be examined for umbilical hernias, cleft palates, open fontanelles, heart
murmurs, and intact rectal structures. Gloves should always be worn when handling puppies and
kittens and their exam should be performed on a towel or soft surface. Neonate examinations
should also be performed away from any infectious animals. Laboratory Values
The laboratory values of neonates are different from that of adult animals. Puppies are born with
an average hematocrit of 47.5% that decreases to 29.9% at 4 weeks of age. The hematocrit then
begins to increase back to normal adult values. In kittens the hematocrit also decreases to
approximately 27% around 4–6 weeks of age. Puppies and kittens also have altered chemistry
values with a slightly increased total bilirubin and increased alkaline phosphatase (ALKP), ɣ glutamyltransferase (GGT), phosphorous and calcium, while their blood urea nitrogen (BUN),
creatinine, albumin, cholesterol and total protein are decreased. The exact cause of increased
liver enzymes is unknown but one hypothesis is that it is due to the high levels of ALKP and
GGT in colostrum. Neonates also have isosthenuric urine as nephrogenesis is not complete until
3 weeks of age. Because of this neonates will have higher concentrations of protein, glucose and
amino acids in their urine. Hypothermia
Neonates are very susceptible to hypothermia as they lack a shivering reflex and the ability to
peripherally vasoconstrict at birth. They also have a large body surface area and lower body fat
which results in increased heat loss. Neonates typically maintain their body temperature through
direct contact with the bitch/queen and litter mates. If neonates are separated from the group
supplemental heat must be administered in the form of an incubator, circulating water blankets,
covered water bottles/gloves or baer hugger. The neonate should also be able to crawl away
from the heat source should they become warm. The ideal neonatal temperature is 90℉ with 55–
65% humidity. It is important that neonates are adequately warmed prior to feeding. When their
temperatures are less than 94℉ a decreased suckle reflex, tachycardia and hypomotile intestines
may occur. At temperatures < 85℉ gastric stasis, bradycardia and hypoglycemia may occur. Fluid Requirements
Neonates have a higher fluid requirement than adults because of their higher percentage of body
water, higher metabolic rate, higher surface area to body weight ratio, decreased renal
concentrating ability, lower body fat and permeable skin. Therefore can become dehydrated or
overhydrated very easily and their hydration status should be reassessed several times a day. This
is best done by weighing the animal on a gram scale as hydration status can be very difficult to
assess in young patients.
Vascular access can also be difficult to achieve in neonates and pediatrics due to their small size
and underlying disease states and therefore jugular or intraosseous catheterization should be
considered. For more information on this topic please see the talk “Vascular Access… Beyond
the Peripheral Catheter.” Neonates that are moderate dehydrated or hypovolemic should be
treated with a bolus of warm isotonic crystalloids (30–45ml/kg in puppies and 20–30ml/kg in
kittens) followed by a constant rate infusion of 120–180 ml/kg/day in neonates and 80–100
ml/kg/day in pediatrics plus additional fluids to account for ongoing losses and dehydration.
Lactated ringers is the ideal fluid choice for these animals as neonates can utilize the lactate for
energy when hypoglycemic. Hypoglycemia is very common in neonates and results from ineffective gluconeogenesis,
decreased liver glycogen stores and increased glucose loss in the urine. Neonates also have
higher glucose requirements than adults as glucose is used as energy for the myocardium and
brain. Signs of neonatal hypoglycemia include lethargy, failure to nurse, mental dullness,
depression, seizures, difficulty breathing and coma. Treatment for hypoglycemia is dextrose
supplementation. A bolus of 0.5–1.5 g/kg of 50% dextrose diluted 1:2 with 0.9% saline should
be administered intravenously followed by a constant rate infusion of dextrose (2.5–10%).
Dextrose supplementation over 5–7.5% should be given through a jugular catheter. Nutrition
Nutrition is essential for neonates as malnutrition can lead to hypoglycemia, gastrointestinal
signs (vomiting/diarrhea) and hypovolemia. If a neonate is not taking in appropriate calories a
surrogate bitch/queen can be utilized. If this is not an option then tube/bottle feeding should be
instituted. Neonates require approximately 15–20 kcal/100 g weight/day which will need to be
given as milk replacer. If a neonate will not suckle from a bottle, tube feedings can be performed.
In animals under 300 grams a 5 French red rubber catheter should be used and in larger animals
an 8–10 French catheter can be used. Tube feedings should only be performed by experienced
staff members since the neonate gag reflex does not develop until 10 days of age and aspiration
can occur.
Monitoring
Neonatal patients should be weighed 4–6 times a day to monitor hydration status and to ensure
weight gain. Kittens should gain between 7–10 grams per day and puppies should gain 1 gram
per pound of anticipated adult weight per day.
Canine Herpesvirus
Canine herpesvirus is one of the most common infectious diseases of neonatal puppies. It results
in depression, decreased suckling, persistent crying, diarrhea, rhinitis, abdominal pain and
neurologic signs which are typically seen prior to death. This is an aggressive disease and death
typically occurs within 24–48 hours of clinical signs. Treatment of this disease is supportive and
prevention is key. Pregnant bitches should be isolated during the last 3 weeks of pregnancy and
the first 3 weeks of parturition to prevent disease. Keeping the neonates warm will also help
decreased replications of this disease and it replicates best at low body temperatures. Neonatal Isoerythrolysis
Neonatal isoerythrolysis is an immune-mediated hemolytic anemia that occurs when colostral
derived antibodies are ingested from a Type B queen. This disease is most common in purebred
kittens and occurs when a Type A or AB kitten nurses on a Type B queen as the queen has
naturally occurring anti-A antibodies. These kittens are born normal but rapidly decompensate
after nursing. Signs of neonatal isoerythrolysis include weakness, icterus, difficulty breathing,
hemoglobinuria and anemia. This can be prevented by blood typing purebred cats prior to
mating. If neonatal isoerythrolysis is suspected the kitten should be taken away from the queen
for the first 24 hours (to prevent absorption of colostrum) and transfused as needed. See
Transfusion Medicine Talk for more information on blood transfusions. Neonatal Septicemia
Septicemia secondary to wounds, respiratory disease, urinary or gastrointestinal infections is
common in neonatal patients. These patients can present severely decompensated in
hypovolemic and/or septic shock. Treatment for neonatal septicemia is aggressive supportive
care including fluid therapy, supplemental heat, nutritional support and antibiotic therapy.
Neonatal drug metabolism differs from that of older animals as neonates have different
absorption, distribution, metabolism and clearance of drugs. This occurs because neonates have
decreased renal clearance, decreased hepatic metabolism and decreased binding of drugs to
albumin. Neonates also have more permeable blood-brain barriers and therefore can be at
increased risk for CNS toxicity/side effects.
Intramuscular drug administration should be avoided in young animals as there is inconsistent
absorption because of their decreased musculature and reduced muscular vasculature. Oral
antibiotics should also be avoided during the first 72 hours of life as neonates have significantly
higher absorption given their increased GI permeability. The intestinal flora is also developing
during this time and is very sensitive to antibiotics. The ideal neonatal antibiotic does not exist but β-lactam antibiotics are one of the safest classes
of antimicrobials for this age group. These antibiotics are typically renally excreted and
therefore the half-lives maybe prolonged in young neonates requiring a decreased dosing
frequency. Parvoviruses
The parvoviruses are highly contagious viruses that can cause severe gastroenteritis in animals.
Affected dogs are typically less than 6 months of age and are most commonly infected with
canine parvovirus type 2 (CPV-2) while cats can be effected with the feline parvovirus (FPV) or
CPV-2. These viruses are extremely hardy and can live for up to 1 year at room temperature and
they can survive freezing temperatures. They are also not susceptible to many disinfectants but
are inactivated by bleach.
Dogs and cats become infected through oral contact with infected feces, soil or fomites. The
parvovirus can be shed through all bodily secretions but are mostly shed in the feces. Shedding
can occur for up to 6 weeks in cats and 2–4 weeks in recovered dogs. The virus replicates within
the oropharyngeal lymphoid tissues and then enters the bloodstream where it infects rapidly
dividing tissues such as the lymphoid tissues, bone marrow and intestinal crypts. The average
incubation period for CPV is 3–7 days in dogs. Dogs with CPV typically present for an acute onset of vomiting, bloody diarrhea, anorexia,
pyrexia and abdominal pain while cats more commonly present for vomiting, anorexia, fever,
lethargy and less commonly diarrhea. Diagnosis of parvovirus is most commonly performed via fecal ELISA tests. The canine fecal
ELISA Parvo tests can also be used to diagnosis feline parvovirus. False negative test results
can occur and if there is a high index of suspicion for parvovirus the ELISA test should be
repeated in 36–48 hours. Other clinicopathologic findings consistent with parvoviruses include
leukopenia and neutropenia, panhypoproteinemia, hypoglycemia, azotemia, elevated liver
enzymes and electrolytes changes. Treatment for CPV and FPV is symptomatic care including
aggressive fluid therapy, broad spectrum antibiotic therapy, antiemetics and nutritional support.
A 2004 review of the CPV reported survival rates of 80–95% with aggressive in-hospital
supportive care while a 2010 study in cats showed a survival rate of 51.1%
Any patient that is suspected to have parvovirus should be immediately placed into an
examination room upon arrival at the hospital and gloves, a disposable gown and surgical booties
should be worn when handling the patient and then removed immediately after exiting the room
and disposed of. A dilute bleach footbath should also be utilized and all surfaces that came into
contact with the animal, including the floor and examination table, should be cleaned with dilute
bleach and a contact time of at least 10 minutes should be utilized. The patient should also be
hospitalized in isolation to prevent further spread of the disease. Summary
Neonatal and pediatric patients differ from their adult counterparts. Awareness of these
differences is vital in the diagnosis, management and treatment of ill neonates.