CHAPTER 2 Birth and the First 24 Hours
There are significant physiologic differences between fetuses and neonates. Puppies and kittens are born much less mature than newborns of many other domestic species and thus are more dependent on care during the first few days of life. The treatment of newborn puppies and kittens can be quite challenging to the practicing veterinarian because of the neonate’s small size and immature organ function. Therefore it is very important for the veterinarian to understand the unique physiology of the neonate.
To avoid a multitude of complications and to best prepare for the event, it is very important to accurately predict when the parturition will occur. There are many different ways to make this prediction, and some ways are more accurate than others (Box 2-1).
BOX 2-1 Methods for predicting delivery date
Normal labor can be broken out into three distinct stages. For the descriptions of the stages of labor, the term usually will be used here to represent a normal range of values. It should be noted that these ranges may not be exact for every bitch or queen and for every circumstance.
Stage I usually lasts 12 to 24 hours. Clinically, bitches/queens may be restless and actively panting, scratching, and digging, whereas other bitches/queens are quiet. For the most part, on the day of delivery, they will not eat. The bitch/queen’s temperature will drop to 98° F (36.7° C) and remain at that low level throughout this stage. Queens may vocalize, turn around in circles, and lick themselves constantly. Internally, cervical dilation starts. Since the cervical opening is at the level of the lumbar vertebrae in dogs, it cannot be palpated but may be visualized through a rigid cystourethroscope. Weak uterine contractions will occur during this stage but are not visible to the human eye. These contractions can, however, be detected by the Whelp Wise service.
Stage II usually lasts 6 to 12 hours. The body temperature rises and returns to its normal level. Internally, the first fetus moves toward the pelvic canal. On entering the pelvic canal, the allantochorionic membrane of the placenta can rupture and a discharge of clear fluid may be noted. Uterine contractions will increase in force and will be outwardly visible. These uterine contractions will ultimately result in the expulsion of the fetus.
Stage III is expulsion of the placenta, usually happening immediately after the successful delivery of the fetus. Throughout the birth process, stages II and III will alternate until all fetuses have been delivered.
Dams/queens should be allowed to resuscitate their newborns. Whenever possible, the following steps should be performed by the mother:
Intervention should only happen if the dam/queen is not showing any interest in the newborn during the first 30 to 60 seconds after delivery. The action of nursing of puppies/kittens releases natural oxytocin and helps strengthen contractions and delivery of the subsequent fetuses.
Assistance in Natural Delivery
If the mother is not performing the previously mentioned duties satisfactorily, then human assistance is required. Fetal membranes should be removed by wiping the neonate with a warm towel and clearing the nose and mouth area first. A bulb syringe or a DeLee’s mucus trap suctioning device can be used to suction out both nostrils and mouth. A gentle rocking of the newborn in a head-down position (while head and neck are supported) can assist with the removal of the remaining fluid from the chest/trachea. Swinging of the newborns is no longer advocated because of potential cerebral hemorrhage from concussion.
The umbilical cord should first be clamped about -inch away from the body wall, then tied off with a piece of suture, and finally dabbed with either a chlorhexidine or Betadine solution. Once the neonate is dry and breathing well, it can be put with the dam/queen. A healthy neonate should actively search for the dam’s teat and should start suckling almost immediately.
Care should be taken in case the dam/queen rejects the neonate and attempts to bite it. In this situation, a light tranquilization with acepromazine (0.01 to 0.02 mg/kg) might be necessary initially and the dam/queen should not be left alone with the offspring until the problem of rejection is overcome. Sometimes, rubbing placental fluids on the neonate may help the mother to recognize it as her own. A few drops of oxytocin may be applied topically to her nostrils to assist in mothering behavior.
At times, injections (Cal-Pho-Sol 1 cc/10 lb subcutaneous [SC]) have been used to help with hypocalcemia-associated aggression. Care must be used with other SC preparations to avoid skin irritations. A dog-appeasing pheromone (DAP) diffuser or DAP collar may also be helpful in creating a calm, comfortable environment in the whelping room.
In cases of aggression it may be necessary to place puppies/kittens in a small plastic box (found at a Walmart or similar store) that has a heating supply (such as a small self-contained heating disk [e.g., Snuggle Safe]) and small round openings cut out for ventilation. Also longitudinal slits should be made in the lid so that the new mother can smell and hear her offspring, as well as see them move. It will help with the desensitization process. The offspring should be removed from the container for supervised and assisted nursing. Usually only 48 to 72 hours are needed to calm new mothers.
In normal labor, the female may show weak or infrequent contractions for up to 2 and at the most 4 hours before giving birth to the first fetus. If the female is showing strong and sustained contractions and a puppy or a kitten is not produced within 30 minutes, a possible obstruction may exist and immediate veterinary advice should be sought.
The dam/queen should be presented for veterinary examination immediately if any evidence of delivery problems is noted (Box 2-2).
BOX 2-2 Clinical signs possibly associated with dystocia
Fetal viability and distress is best diagnosed with the use of ultrasound. Since the normal fetal heart rates are between 180 to 220 beats per minute (bpm), a heart rate below 180 bpm indicates fetal distress. If the fetal heart rate falls below 150 bpm, an emergency is indicated and requires an immediate cesarean section (C-section).
If a C-section is deemed necessary, several aspects of this procedure should be considered to maximize success and ultimate survivability of the fetuses. The primary considerations and focus should be placed on preparation, choice of anesthesia, careful use of approved drugs, and speed of execution.
A metoclopramide injection (0.1 to 0.2 mg/kg) should be considered if there was a recent meal ingestion or if some puppies were already born and the mother has ingested placentas; in very large litters; or when there is a lot of pressure on the stomach, which can facilitate regurgitation or vomiting. Before induction, the female should receive 10 to 15 minutes of preoxygenation via a mask. Premedication with anticholinergics (atropine, glycopyrrolate) may be used to maintain a higher heart rate in the mother. An intravenous (IV) catheter needs to be inserted, and sodium chloride (NaCl) fluids should be given at a surgical rate of 10 ml/kg/hr to maintain the proper blood pressure during the surgery. For an elective C-section in dogs, short-acting steroids (Solu-Delta Cortef) can be administered 2 to 12 hours prior to surgery at a dose of 1 mg/kg and have been shown to be beneficial in litter resuscitation. The induction itself may be performed with propofol (4 to 6 mg/kg) administered intravenously or gas induction via a mask. The use of optimal anesthetic protocols will improve neonatal survival. Certain drugs, such as ketamine, thiopental, and xylazine, should be avoided. Once induced, the anesthetic state should be maintained with an Isoflurane or Sevoflurane anesthetic gas. A local block with either a lidocaine or a bupivacaine will help with keeping the anesthesia levels lower until a centrally acting analgesic can be given. At this point, it is critical to remove all the fetuses from the uterus as expeditiously as possible so that the moderately depressed state from anesthesia will not worsen the already present distress of the fetuses, which necessitated the procedure in the first place.
After all fetuses have been removed, focus can once again return to the mother and successful completion of the procedure. It should also be noted that the sooner the procedure can be completed and the mother can be safely reunited with the newborns the better. After all puppies are removed, a standard pain control IV dose of butorphanol or buprenorphine can be given to keep the mother comfortable.
Neonatal Resuscitation after Cesarean Section
Resuscitation of neonates delivered by C-section involves mostly the same process as outlined in the section on natural birth, except that many puppies will need resuscitation simultaneously as opposed to a more evenly distributed and extended timeframe. Additionally, the fetuses that were in distress before the C-section began should be given priority and may require more extreme measures to resuscitate (see next section on more extensive resuscitation measures).
Once neonates are pink and breathing well on their own, they should be placed into a warm environment like an incubator to await their mother’s recovery. At that time, all puppies/kittens should be checked for congenital defects like cleft palates, atresia ani, hydrocephalus, and so on.
Extensive Resuscitation Measures
After the initial rubbing, suctioning, and stimulating, if a newborn does not start to breathe on its own within 30 to 60 seconds, then additional and more extensive assistance is required. These more extensive measures should be employed after a quick but careful evaluation of the neonate’s condition because the clinician will want to take the least invasive path possible while achieving the same result.
Thicker secretions can be removed through the use of an airway suction catheter in the mouth (DeLee aspirator). This device provides the application of controlled suction and allows inspection of the pharynx to see if meconium may have been aspirated because of in utero distress. Ventilatory support should include a constant flow of oxygen via a tightly fitted oxygen mask providing positive pressure ventilation. If this is not effective after 3 to 5 minutes or if the newborn’s heart rate starts to drop, then intubation should be attempted. Although it is difficult to insert, a 2-mm endotracheal tube or a larger gauge IV catheter could be used to provide positive pressure ventilation in an attempt to inflate the lungs. Oxygen toxicity is usually not a major concern as few neonates are maintained in oxygen-rich environment for longer than the first 10 to 15 minutes.
Doxapram is thought to work via central stimulation. The effectiveness of this drug is significantly diminished if the brain is hypoxic since the action requires the central processing of the incoming signal from the periphery. Thus doxapram is unlikely to be beneficial to the apneic hypoxic neonate.
The use of Jen Chung acupuncture point GV26 has been advocated by some. A 25-gauge needle is inserted into the nasal philtrum at the base of the nostrils where it joins the haircoat and rotated clockwise when it reaches the bone.
Cardiac stimulation should follow ventilatory support through the use of direct chest compressions. If there is no improvement, epinephrine is the drug of choice for neonatal cardiac arrest. It has been shown to increase the mean arterial blood pressure and improve oxygen delivery to the heart. Suggested doses of epinephrine range from 10 µg/kg to 200 µg/kg IV. Caution should be used with higher doses because of the risks of associated hypertension. The preferred route of administration is either via IV through the umbilical vein or via an intraosseous (IO) route through the insertion of a 22- or 25-gauge needle into the humerus or femur. Endotracheal administration should be avoided because of associated vasoconstriction of the tracheal mucosa.
Since bradycardia is usually caused by hypoxemia-induced myocardial depression and not vagal mediation, the use of atropine is not recommended because it can cause a rebound tachycardia and exacerbate myocardial oxygen deficit.
The use of sodium bicarbonate is controversial but potentially could be beneficial in the treatment of neonatal acidosis in cases in which resuscitation takes longer than 20 to 30 minutes. This drug should only be administered to a patient who is well ventilated. The recommendation is to dilute it 1:1 with 5% dextrose (0.5 mEq/ml) and administer at a dose of 0.5 to 1 mEq/kg IV via the umbilical vein slowly over 2 to 3 minutes.
In the past, it was recommended that naloxone (0.1 mg/kg intramuscular [IM]) should be used in all apneic neonates. This was based on the findings that there is a surge of endorphin release during the time of parturition and especially during a stressful birth, which was associated with respiratory depression in newborns. Modern research has showed that the use of this medication is no longer effective and may be detrimental if given to a hypoxemic patient since it may worsen the existing bradycardia. It may be beneficial only in cases in which the neonate shows signs of respiratory depression and the mother received an opioid injection before or during the C-section surgery.
The clinician should examine all puppies and kittens for obvious congenital defects. If severe abnormalities are noted, humane euthanasia of the affected neonate(s) should be considered so that resuscitation efforts can be focused on the healthy ones.