Normal Labor in Bitches and Queens
Stage I labor in bitches and queens normally lasts 12–24 hours, during which time myometrial uterine contractions increase in frequency and strength, and the cervix dilates. No abdominal efforts (visible contractions) are evident during stage I labor.
Female dogs and cats may exhibit changes in disposition and behavior during stage I labor, becoming reclusive, restless, and nesting intermittently, often refusing to eat and sometimes vomiting. Panting and trembling may occur. Normal vaginal discharge is clear and watery.
Tocodynamometry, using a pressure-sensitive device to monitor and measure the strength and frequency of uterine contractions, can detect stage I labor in both bitches and queens (see tocodynamometry images, bitch and queen).
Courtesy of Dr. Autumn Davidson.
Courtesy of Dr. Autumn Davidson.
Normal stage II labor is marked by visible abdominal efforts, which are accompanied by myometrial contractions that culminate in delivery of a neonate. Typically, these efforts should not last > 1–2 hours between puppies or kittens, although great variation exists. The entire delivery can take 1 to > 24 hours; however, normal labor is associated with shorter total delivery time and intervals (30–60 minutes) between neonates, with delivery ideally completed in approximately 7–9 hours. Vaginal discharge can be clear, serous to hemorrhagic, or green (uteroverdin, abnormal).
Typically, female dogs and queens continue to nest between deliveries and may nurse and groom neonates intermittently. Anorexia, panting, and trembling are common.
Stage III labor is defined as delivery of the placenta. Bitches and queens typically vacillate between stages II and III of labor until delivery is complete. During normal labor, all fetuses and placentas are delivered vaginally, although they may not be delivered together in every instance.
Dystocia in Labor and Delivery in Bitches and Queens
Dystocia results from maternal factors (uterine inertia, pelvic canal anomalies), fetal factors (oversize, malposition, malposture, anomalies), or a combination of both. The diagnosis of primary inertia (contractions never begin) requires tocodynamometry. Clinically, uterine inertia developing after delivery of one or more neonates (secondary inertia) is the most common cause of dystocia and can also be diagnosed with tocodynamometry.
Dystocia can be objectively diagnosed if uterine contractility is inappropriate (generally infrequent, weak myometrial contractions) for the stage of labor or if excessive fetal stress results from labor. Subjectively, dystocia is diagnosed if stage I labor is not initiated at term, if stage I labor is > 24 hours without progression to stage II, if stage II labor does not produce a vaginal delivery within 1–2 hours, if fetal or maternal stress is excessive, if moribund or stillborn neonates are present, or if stage II labor does not result in the completion of deliveries in a timely manner (within 4–9 hours).
Uterine and fetal monitors can be used to detect and monitor labor and fetal viability and to manage dystocia. Unresponsive uterine inertia, obstructive dystocia, aberrant uterine contractions, and progressive fetal distress without response to medical management are indications for a cesarean section.
Medical management includes administration of calcium gluconate and oxytocin based on the results of monitoring. Drugs are given only after 8–12 hours of an established contraction pattern (stage I labor) as detected by the uterine monitor and only if inertia is detected when stage II labor is anticipated. Premature administration of drugs results in suboptimal response.
Generally, the administration of calcium increases the strength of myometrial contractions, while oxytocin increases the frequency. 10% calcium gluconate (1 mL/22 kg, SC, every 6 hours)) is given when uterine contractions are ineffective or weak. It can be administered SC (no more than 6 mL/site), avoiding the potential for cardiac irritability associated with IV administration.
Oxytocin (0.5–2 U in bitches; 0.25–1 U in queens, once) is given when uterine contractions are less frequent than expected for the stage of labor. The most effective time for treatment is when uterine inertia begins to develop, before the contractions stop completely. High doses of oxytocin saturate the receptor sites and make it ineffective as a uterotonic. If fetal stress is evident (persistent or worsening bradycardia) and response to medications is poor, cesarean section is indicated.
Postpartum Care in Bitches and Queens
Ultrasonography, radiography, or palpation (less reliable) should be used to determine that all puppies or kittens have been delivered. Routine postpartum administration of antimicrobials is unnecessary in healthy dams with nursing neonates. Placentas can be rapidly consumed, be passed unnoticed, or pass normally within 24 hours.
A single dose of oxytocin (0.25–1 U/dam, SC) at the completion of labor might help uterine involution. The dam’s body temperature and the character of the postpartum discharge (lochia) and milk should be monitored.
Normally, lochia is dark red to black, odorless, and heavy for the first few days after parturition. It is not necessary that the dam consume the placentas. Ligation and disinfection of the neonatal umbilicus with 2% tincture of iodine helps prevent bacterial contamination and subsequent peritonitis.
The neonate should be weighed accurately as soon as it is dry and then twice daily for the first week. Any weight loss or failure to gain 10% of body weight/day beyond the first 24 hours indicates a potential problem, for which the neonate should be given immediate attention (eg, supplemental feeding, assisted nursing, evaluation for sepsis). (See also the discussion on management of the neonate in dogs and cats.)
