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Management of the Neonate in Dogs and Cats

By

Autumn P. Davidson

, DVM, MS, DACVIM, Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis

Medically Reviewed Dec 2022
Topic Resources

The neonatal period in dogs and cats encompasses the first 21 days of life. Neonatal mortality rates of 9%–26% have been reported; they are highest in the first week of life. Common causes of neonatal morbidity in dogs and cats include:

  • poor prepartum condition of the dam

  • dystocia

  • poor nursing/lack of colostrum

  • trauma

  • infectious diseases

  • congenital defects

Care by a veterinarian in the immediate neonatal period improves survival of the neonates and reduces morbidity in the dam. Interventions that may improve survival include:

  • improved maternal nutrition

  • parasite control programs

  • dogs - determining due date by ovulation timing with serial progesterone testing (due 62–64 days from ovulation or 64–66 days from initial rise indicating LH peak) or minimally by vaginal cytology to identify the diestrual shift (due 56–58 days later)

  • cats - determining due date by counting 65–66 days from first ovulatory copulation

  • active management of labor and delivery (eg, tocodynamometry and fetal doppler monitors)

  • timely medical or surgical intervention in dystocia

  • systematic neonatal resuscitation regardless of birthing method

  • neonatal APGAR scoring

  • daily evaluation of neonatal eliminations, vigor, weight

  • daily evaluation of dam’s mammary glands, vulvar discharge, temperature, appetite, and maternal skills

Immediate Postpartum Resuscitation of a Neonatal Puppy or Kitten

Neonatal resuscitation, puppy
VIDEO

Neonatal resuscitation occurs after cesarian sections but should also take place with any natural delivery to the extent that the neonate must attain oxygenation, vigor, and effective suckling within moments of birth. Neonatal resuscitation should take place in a warm environment (overhead heat lamp, warm air blanket). All personnel assisting with neonatal resuscitation should keep strict hygiene (eg, fresh scrubs or lab coats, thorough hand-washing or wearing gloves). Neonatal resuscitation involves the same “ABCs” as any cardiopulmonary resuscitation:

  • "A" - Airway

    • Promptly remove fetal membranes (from the face first).

    • Gently suction fluid from the airway using a DeLee aspirator or preemie bulb syringe while holding the neonate's head lower than the thorax.

    • Neonates should not be swung to expel airway fluid, which can cause concussion or cerebral hemorrhage.

    "B" - Breathing

    • Briskly rub and dry the neonate with a warm towel, with focus on the muzzle and thorax (to stimulate the respiratory center).

    • In hospital settings, provide 100% O2 via face mask for all puppies during initial resuscitation.

    • Evaluate mucous membrane color, heart rate, and breathing effort. Spontaneous breathing and vocalization at birth are positively associated with survival through 7 days of age.

    • If the neonate is cyanotic, and feeble breathing efforts without vocalization or movement (vigor) persist, recheck and reclear airways. Supply positive pressure ventilation via 100% O2 through a snug face mask (or room air via mask ventilator if in a home setting) while continuing to rub the thorax and monitor heart rate.

    • Use of doxapram as a respiratory stimulant is unlikely to improve hypoxemia associated with hypoventilation and is not recommended.

    • Jen Chung (GV26) acupuncture point stimulation of respiration occurs when a 27-gauge or acupuncture needle is inserted into the nasal philtrum at the base of the nares and rotated when bone is contacted.

    • If positive pressure ventilation with a face mask is ineffective after > 5 minutes, endotracheal intubation and a rebreathing bag (using a 2-mm endotracheal tube or a 12- to 16-gauge IV catheter) is advised.

    "C" - Cardiovascular/Circulation

    • An improvement in heart rate should follow ventilation support; myocardial hypoxemia is the most common cause of neonatal bradycardia or asystole.

    • Atropine is currently not advised in neonatal resuscitation. The mechanism of bradycardia is hypoxemia-induced myocardial depression rather than vagal mediation, and anticholinergic-induced tachycardia can actually worsen myocardial oxygen deficits.

    • If no heartbeat is detected, direct transthoracic cardiac compressions are advised as the first step; epinephrine diluted 1:9 is the drug of choice for cardiac arrest/standstill (0.0002 mg/g administered best by the IV or intraosseous route). Venous access in neonates is challenging; the single umbilical vein is rapidly thrombosed and may only reach hepatic parenchyma. The jugular veins may also be used for venous access. The proximal humerus, trochanteric fossa of the femur, and proximomedial tibia offer intraosseous sites for drug administration.

DeLee Aspirator

APGAR scoring at 5 and 60 minutes after birth can be used as a simple way to determine instantaneous neonatal health in newborn cats and dogs. Neonates with low APGAR scores are at increased risk for mortality; this prompts more intensive intervention during the immediate neonatal period:

  • ensure the neonate is warm, nursing, gaining weight, and eliminating

  • consider supplemental nutrition, fluids, antibiotics

Factors scored by various investigators include vigor (spontaneous movement, suckle attempts, rooting, and righting reflex present), irritability (response to rubbing or toe pinch, vocalization), mucous membrane color, heart and respiratory rates, each on a scale from 0-2. Three neonatal classes of viability are identified based on the total scores in each category: 0–3, newborns with severe distress; 4–6, newborns with moderate distress; 7–10, normal newborns with no distress and highest survival rates. Most of these factors are subconsciously evaluated by experienced breeders and veterinary nurses or doctors, but scoring gives credibility and improves consistency of the observations.

Chilled neonates may not respond to resuscitation. Body temperature drops rapidly when a neonate is damp. Keeping the neonate warm is important during resuscitation and in the immediate postpartum period. During resuscitation, placing the chilled neonate’s trunk into a warm water bath (95°–99°F) can improve response. Working under a heat lamp or within a Baer hugger warming device is helpful. Rubbing and drying neonates with soft towels also helps to raise body temperature. Towels should be changed to fresh, dry ones if they become too wet during resuscitation.

Neonates lack glucose reserves and have minimal capacity for gluconeogenesis. Providing energy during or just after prolonged resuscitation efforts becomes critical. Clinical hypoglycemia (blood glucose levels < 30–40 mg/dL) can be treated with dextrose solution IV or intraosseous, at a dosage of 0.5–1 g/kg (0.0005–0.001 g/g body wt) dextrose using a 5%–10% solution, or a dosage of 2–4 mL/kg (0.002–0.004 mL/g body wt) of a 10% dextrose solution. (A 500-g neonate would get 1–2 mL.)

Single administration of parenteral glucose is adequate if the hypoglycemic puppy can then be fed or nurses. If a neonate is too weak to nurse or suckle, 0.05–1 mL of warmed 5% dextrose can be administered orally by stomach tube every 15–30 minutes until the neonate is capable of suckling. If colostrum or milk can be acquired from the dam, it can be administered in the same way and repeated every 2 hours until the neonatal is able to nurse on its own.

Dextrose solution (50%) can be applied to the gums if the neonate has adequate circulation. This may be more easily done by practitioners with less experience resuscitating neonates than giving dextrose IV or IO. However, for severely hypoglycemic, nonresponsive neonates, the IV and IO routes are preferred.

After resuscitation, neonates should be placed in a warm box (a styrofoam picnic box with ventilation holes is ideal) with warm bedding until they can be presented to their dam. They can also be placed in a veterinary or human incubator, which allows for adjustment of temperature, humidity, and O2 level. Nursing should be encouraged, guided, and permitted as soon as possible, even during recovery from anesthesia, under supervision. Neonates delivered by Cesarean section should be left alone with the dam only after she is fully recovered from anesthesia and exhibiting good maternal behavior (this may take 24–48 hours); otherwise, nursing should be directly monitored and permitted every 1–2 hours.

When to Stop Resuscitation

Resuscitation may be stopped when there has been no response after 15–20 minutes of effort (continued agonal respiration, bradycardia) or when a serious congenital defect has been detected (cleft palate, severe murmur, gastroschisis, large omphalocele, large fontanel).

Husbandry in the First Days of Life of a Puppy or Kitten

Within the first 24 hours of a natural delivery, a complete physical examination should be performed. Lack of cleft palate, a normal umbilicus, and functional urethral and anal openings should be established. A fontanelle, if present, should be small. The oral cavity, hair coat, limbs, umbilicus, and urogenital structures should be visually inspected. The mucous membranes should be pink and moist, a suckle reflex present, the coat full and clean, and the urethra and anus patent. A normal umbilicus is dry without surrounding erythema. The thorax should be ausculted; vesicular breath sounds and a lack of murmur are normal. Heart murmurs of intensities 1–3/6 can sometimes be heard in neonates and may be physiologic. The abdomen should be pliant and not painful.

A normal neonate will squirm and vocalize when examined and will nurse and sleep quietly when returned to the dam. Healthy neonates will attempt to right themselves and orient by rooting toward their dam. Neonates are highly susceptible to environmental stress, infection, and malnutrition. Proper husbandry is critical and should include daily examination of each neonate for vigor and recording of weight.

Warmth of a Neonatal Puppy or Kitten

Puppies and kittens lack thermoregulatory mechanisms until 4 weeks of age; thus, the ambient temperature must be high enough to facilitate maintenance of a body temperature of at least 97°F (36°C). Hypothermia negatively impacts immunity, nursing, and digestion. Exogenous heat should be supplied, best in the form of an overhead heat lamp at appropriate distance to avoid overheating and burning. Heating pads run the risk of burning neonates incapable of moving away from excessively hot surfaces. Environmental humidity of 55%–65% is recommended.

Table
Table

Chilled neonates must be rewarmed slowly (30–60 minutes) to avoid peripheral vasodilation and dehydration. Tube feeding should be delayed until the neonate is euthermic. Hypothermia induces ileus, and regurgitation and aspiration can result.

Immunity of a Neonatal Puppy or Kitten

Incompletely developed immune systems during the first 10 days of life make neonates vulnerable to systemic infection (most commonly bacterial and viral). Puppies must ingest adequate colostrum promptly after birth to acquire passive immunity. The intestinal absorption of IgG generally ceases by 24 hours after parturition and may begin within 4–8 hours of birth. In cases of initial nursing failure, some authors recommend adult dog or cat pooled serum PO for neonates < 12 hours old and SC if they are > 12 hours old at 0.02 mL/g body weight divided prn. Neonates should be encouraged to suckle promptly after resuscitation is completed; this usually necessitates close monitoring after a cesarean section, because the dam has not fully recovered from anesthesia. Maternal instincts (protecting, retrieving, grooming, nursing) usually return within 24-48 hours.

The umbilicus of neonates should be trimmed 1 cm from the abdominal wall, ligated, and may be treated with 2% tincture of iodine immediately after resuscitation to reduce contamination and prevent ascent of bacteria into the peritoneal cavity (omphalitis-peritonitis).

Umbilical Care

Neonatal bacterial sepsis can cause rapid deterioration and result in death if not recognized and treated promptly. Predisposing factors include infection of the dam (metritis, endometritis, mastitis), a prolonged delivery/dystocia, improper feeding of replacement formulas, contaminated environment, the use of ampicillin, stress, low birth weight (< 350 g for a medium-size breed dog), and chilling, with a body temperature < 96°F.

The organisms most frequently associated with sepsis are Escherichia coli, streptococci, staphylococci, and Klebsiella spp.

Pre-mortem diagnosis of sepsis can be challenging, because sudden death may preclude recognition of clinical signs. Clinical signs that may indicate sepsis include:

  • a decrease in weight gain

  • failure to suckle

  • hematuria

  • persistent diarrhea

  • unusual vocalization

  • abdominal distention and pain

  • necrosis and sloughing of the extremities

  • hypothermia

  • dyspnea

  • regurgitation or vomiting

Prompt therapy with broad-spectrum, antibiotics; improved nutrition via supported nursing, tube feeding, or bottle feeding; maintenance of body temperature; and appropriate fluid replacement are indicated. Antibiotic therapy should ideally be based on culture and sensitivity, and the selected antibiotic be safe to use in neonates considering their physiologic immaturity. The third-generation cephalosporin ceftiofur sodium is an appropriate empirical first choice for neonatal sepsis, because it alters normal intestinal flora minimally and is usually effective against the causative organisms. Another alternative empirical choice is amoxicillin-clavulanic acid. Ceftiofur sodium should be administered at a dosage of 0.0025 mg/g, SC, twice daily, for no longer than 5 days. A protocol for preparation and use of ceftiofur is as follows:

  • Reconstituting a 1g vial with 20 mL bacteriostatic or sterile water results in a 50 mg/mL solution. For neonates, an additional dilution of 1 part 50 mg/mL ceftiofur to 9 parts sterile water yields a final solution that is 5.0 mg/mL. This dose needed can be used and the remainder frozen in 3.0 mL labeled quantities.

  • Once reconstituted, ceftiofur will be stable for:

    • 12 hours at room temperature

    • 7 days if refrigerated

    • 8 weeks if frozen, then 7 additional days when thawed and refrigerated

  • The neonatal dosage is 2.5 mg/kg (0.0025 mg/g), SC, twice daily. (A 500g neonate will get 0.25 mL, SC, twice daily.)

Because neonates < 48 hours old have reduced thrombin levels, presumptive therapy with vitamin K1 at 0.5–2.5 mg/kg can be used (0.01–1 mg/neonate, SC) if a coagulopathy is suspected (umbilical bleeding, hematuria, epistaxis).

Nutrition of a Neonatal Puppy or Kitten

Neonates have minimal body fat reserves and limited metabolic capacity to generate glucose from precursors. Glycogen stores are depleted shortly after birth, making adequate nourishment from nursing vital. Even minimal fasting can result in hypoglycemia. Hypoglycemia can also result from endotoxemia, sepsis, portosystemic shunts, and glycogen storage abnormalities. Oral fluid and glucose replacement may be preferable if the neonate has an adequate swallowing reflex and is not clinically compromised. The neonatal caloric requirement is 133 cal/kg/day during the first week of life, 155 cal/kg/day for the second, 175–198 cal/kg/day for the third, and 220 cal/kg/day for the fourth week.

Commercially manufactured milk replacement formulas are superior to homemade versions, but none is equal to the dam’s milk. The use of milk obtained from the dam can be considered and is superior if available. An osmotic diarrhea (usually yellow, curdled fecal appearance) can result from overfeeding formula, necessitating diluting the product 50% with water or a balanced crystalloid solution.

Neonates should gain weight steadily from the first day after birth (a transient mild loss of a maximum 10% of birth weight is acceptable on day 1), with puppies gaining 1–3 g/day/kg (2.2 lb) of anticipated adult weight and kittens 50–100 g/week. Neonatal weights should be recorded daily for the first 2 weeks, then every 3 days until 1 month old. Healthy, well-nourished neonates are quiet and sleep when not nursing. The normal neonatal weight gain is an increase of 5%–10% body wt/day.

Neonatal Anesthesia of a Puppy or Kitten

Anesthesia of the neonate may be necessitated by an emergency or for an elective procedure. The distribution and metabolism of drugs are different in neonates than in adults. Neonates have decreased protein binding and increased permeability of the blood-brain barrier. Decreased protein binding is due to lower albumin levels with a lower affinity for drugs. Neonates have higher body water content and lower fat content than adults. This results in a greater initial volume of distribution for some drugs. In most neonates, the ability to metabolize drugs (via conjugation, hydrolysis, oxidation, and reduction) is reduced, as are renal clearance mechanisms.

Nephrogenesis in puppies is not complete until the third week of life; the outer cortical nephrons are the last ones to become fully functional. The ability of the neonatal kidney to produce a concentrated urine is less than that of the adult and glomerular filtration and tubular secretion are also decreased, so fluid balance is more labile in neonates. The differences in neonatal respiratory function mean that inhaled agents will have a more rapid onset and recovery. Neonates have immature central and peripheral nervous systems and immature neuromuscular junctions, such that less general/local anesthetic is required to produce anesthesia/local block than in adults.

Fluid support is indicated with neonates, but fluid overload is a potential danger because of the capacity of the fluid lines used for larger animals. To avoid this problem, tubing with a much smaller internal diameter should be used. Care must also be taken to ensure that the lines do not contain any air, because these very small patients may still have communication between the left and right atrium, making it possible for IV air to result in coronary or cerebral emboli.

Core body temperature should be monitored, and hypothermia treated as soon as possible. A supplemental source of heat should be available (circulating water blanket or warm air blanket) to prevent hypothermia, because many of the anesthetic drugs eliminate the ability of the neonate to thermoregulate (which is still immature), and neonates are more prone to hypothermia than adults. Premedication with an anticholinergic is acceptable and usually sufficient by itself. Most neonates tolerate a simple mask induction with an inhalant such as isoflurane or sevoflurane. Propofol can be used as an induction drug in young animals. Maintenance by mask avoids the potential for trauma during intubation in tiny neonates, but less control of the airway is achieved.

During anesthesia of neonates, supporting and monitoring cardiopulmonary function is especially important. Cardiac output in neonates depends on heart rate; preventing bradycardia is more important than in adults. Monitoring blood pressure is also important. If hypotension is detected or tissue perfusion judged inadequate, treatment should be instituted. Initial therapy should include reducing the amount of anesthetic, if possible, and increasing the rate of fluid administration. If these treatments are ineffective, it is probably better to use a positive inotrope/chronotrope than a peripheral vasoconstrictor to try to increase blood pressure (unless it is very low, and a vasoconstrictor is needed to raise the pressure long enough to allow other therapies to work). Dopamine has been shown to increase blood pressure in puppies < 10 days old at 5–10 mcg/kg/min but has little effect on heart rate or cardiac output. Dobutamine appears to have little effect at clinical doses.

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