Dystocia is a difficult or prolonged parturition that is a reproductive emergency requiring medical or surgical intervention by a skilled team to minimize perinatal . Dystocia is the medical term used to diagnose a difficult birthing experience. Learn more about Dig Birth Difficulties and treatment at Learn about the veterinary topic of Dystocia in Small Animals. Find specific details on this topic and related topics from the MSD Vet Manual.
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Dystocia is a common emergency in canine patients. The clinician must rapidly identify the stage of labor and determine whether veterinary attention is warranted. Physical examination, vaginal examination, abdominal radiography, abdominal ultrasonography, fetal heart rates, and intrauterine pressures assist the clinician in diagnosing and managing patients with dystocia.
Dystocia, the difficulty in passing the fetus through the pelvic canal, is a common small animal emergency. Significant disparity exists between the events of normal and abnormal canine parturition.
Positive clinical outcomes can be expected only when the clinician has a thorough understanding and knowledge of normal canine parturition, the pathogenesis and underlying etiology of dystocia, the criteria for diagnosing dystocia, and the appropriate medical and surgical interventions.
The dam’s whelping date may be determined using breeding dates, time of luteinizing hormone LH peak, ovulation date, or the first day of diestrus. Gestation duration in the bitch is approximately 57 to 72 days average: The gestation length after the first day of diestrus is 56 to 59 days, 1 but this date is rarely known for dystocia patients.
Okkens et al 3 found that gestation duration is negatively correlated with litter size in litters of seven or fewer pups and that there is no difference in length of gestation between primiparous and multiparous bitches.
Once the appropriate gestation time has passed, the complex cascade of events leading to delivery begins. Understanding the neuroendocrine cascade of parturition assists the clinician in managing the dam and understanding the etiology of dystocia. The accepted neuroendocrine model of canine parturition is initiated by the fetus. The fetal hypothalamic-pituitary-adrenal axis is activated by fetal stress and leads to the secretion of fetal glucocorticoids.
Prostaglandins are luteolytic, contribute to the decline in circulating progesterone, remove the inhibition of myometrial contractility, and mediate the effects of oxytocin on the uterus.
Relaxin hormone, produced by the ovary and placenta, assists fetal passage by allowing the interpubic ligament to elongate and the pubic bones to separate. Restless behavior, anorexia, and nesting may all be seen several days before parturition as well as during stage 1 of labor.
A recent study 8 found no association between body temperature decline and impending parturition but did find a significant increase in body temperature 12 hours after the onset of cnaine was identified.
Limited conclusions may be drawn from this investigation owing to its small number of subjects. The authors suggested that direct measurement of progesterone decline and prostaglandin elevation is a more reliable indicator of parturition and that any elevation in the bitch’s temperature at the end of pregnancy without expulsion of fetuses could indicate dystocia. Each stage of labor has a predictable group of clinical signs and duration.
Stage 1 labor begins with indiscernible uterine contractions and progressive cervical dilation. This stage lasts 6 to 12 hours, but primiparous bitches may persist for up to 24 hours. Behavior signs associated with stage 1 labor include nesting, panting, and restlessness. The second stage of labor is the active expulsion of the fetus from the birth canal; the visible abdominal straining matches the strong uterine contractions.
Clear vaginal discharge, the allantoic fluid, is seen as stage 2 labor begins and precedes each puppy. The first fetus is normally delivered within 30 minutes of the start of stage 2 labor but may not be delivered for 2 to 4 hours due to weak or uncoordinated uterine contractions.
Stage 2 labor should be complete within 12 to 24 hours, with a fetus produced every 0. A recent case report 9 described the delivery of a healthy puppy after a hour interval between puppies and hour duration of stage 2 labor—an interesting outlier within the dystocia patient population. Stage 3 labor is the expulsion of the placenta, which takes place 5 to 15 minutes after the delivery of the fetus. Multiple placentas may be passed after several puppies are delivered close together.
It is not uncommon for the bitch to bite the amniotic and allantoic membranes, sever the umbilical cord, and ingest the placenta after parturition. Postpartum findings in the bitch may include mild fever, transient vomiting and diarrhea, and lochial discharge.
Lochial discharge, produced by hemoglobin breakdown, is normal after parturition and is associated with uterine involution.
Veterinarians and their support staff are routinely confronted with phone calls and inquiries regarding canine parturition. The criteria in see Box. The criteria are intentionally stringent to facilitate earlier examination of the dam by veterinary personnel and reduce neonatal complications associated with prolonged dystocia. Dystocia has conventionally been described as being of maternal or fetal origin. Uterine inertia is the failure to expel a fetus from the uterus when no obstruction exists; it can be classified as primary or secondary.
Complete primary uterine inertia occurs when stage 2 labor fails to start and no puppies are delivered. Partial primary uterine inertia is defined as initiation of normal labor but failure to deliver all puppies.
Primary uterine inertia can develop because of litter size: Obstructions can include maternal changes or characteristics such as a narrow pelvis, congenital malformation, pelvic trauma, neoplasia or abscess, vaginal stricture, uterine torsion, uterine or vaginal prolapse, and vaginal hyperplasia. Fetal anatomic and orientation changes accounted for most reviewed cases of fetal dystocia Several dog breeds are associated with an increased risk for dystocia.
Scottish terriers and Boston terriers have inherited characteristics that predispose them to obstructive dystocia. Another study 12 of dystocia cases in Sweden did not find a significant breed disposition. Accurate identification of breed predispositions to dystocia has been limited by local breed popularity and failure of investigators to obtain a representative sample of the dystocia patient population.
Initial evaluation of the dam requires an accurate history and thorough physical examination. Pertinent information includes breeding dates, ovulation date, vaginal cytology, and preovulatory LH peak date, when available, to establish a whelping date.
An accurate history of the dam’s behavior for the previous 24 to 48 hours will help define the stage of labor and assist the clinician in deciding which interventions are indicated. Owners should also be questioned about the dam’s previous reproductive history, age, and breed and any treatments or manipulations performed before presentation. Physical examination of the bitch should be efficient, yet thorough, and should cover all major body systems, with particular focus on the cardiovascular system and urogenital tract.
Canine dystocia–a review of the literature.
Abdominal palpation is performed to check for the presence and position of pups, uterine contractions, and signs of abdominal pain, which may indicate uterine pathology.
Long hair around the vulva should be clipped and the skin cleaned in preparation for a vaginal examination.
Sterile gloves are used during the vaginal examination, during which the clinician may detect a fetus, vaginal septa, masses, strictures, or pelvic abnormalities. Fetal presentation may also be determined.
Canine dystocia–a review of the literature.
Without vaginoscopy, cervical dhstocia is impossible in most bitches, but vaginal vault diameter and muscular tone are described as possible indicators of cervical dilation. The caninne vaginal wall should be digitally stimulated feathering to see if strong abdominal contractions can be elicited Ferguson reflex.
Lack of response to the Ferguson reflex may indicate that the bitch is experiencing uterine inertia, is not cankne labor, or is exhibiting voluntary inhibition because of excessive stress and excitement. Abdominal imaging is important in the continued workup and management of the dam.
Radiographs can detect mineralized fetal skeletons 43 to 54 days after breeding 15 or 45 days after the LH peak. Radiography is a poor modality to assess fetal viability because the typical changes denoting fetal death intrafetal gas, collapse of the spinal dysttocia, and overlap of skull bones do not appear until approximately 6 to 24 hours after fetal death.
Abdominal ultrasonography has not proven useful in estimating gestational age at or around the time of parturition 17,18 ; however, it is an excellent method of assessing fetal viability because it allows visualization of fetal movements and heart rates. An experienced ultrasonographer can also estimate fetal size dystoccia measuring fetal biparietal and thoracic diameters; these measurements can then be compared to the dam’s pelvic diameter on radiographs to determine oversize.
Survey blood work with priority given to packed cell volume and total protein, blood urea nitrogen, glucose, and calcium levels is beneficial to complete the patient assessment. Medical management of the dam may cajine initiated before some of the above diagnostics are completed.
Management includes digital or forcep fetal manipulation and the administration of medications to augment uterine contractions see Box.
When a fetus is detected within the vaginal canal, the clinician may attempt to extract it. Fetal extraction should be accomplished using generous amounts of sterile, water-soluble lubricant and digital manipulation. Based on vaginal anatomy, the fetus should be gently pulled caudoventrally, with care not rystocia exert excessive traction on the fetal limbs.
The puppy’s shoulders or pelvis may be canibe into the dorsoventral plane of the dam’s pelvis to provide cainne greatest cajine for passage of the body. Use of instrumentation to manipulate and extract the fetus is possible but is not recommended due to the risk of fetal and maternal injury. When maternal and fetal obstructions have been ruled out, the stimulation of uterine contractions may be initiated. This may be accomplished by having the owners walk the dam or by the clinician feathering the dam’s dorsal vaginal wall.
While there has been little investigation into the optimum dose or route, the recommended dosage of oxytocin is 1. Investigators have found that oxytocin-induced myometrial contractions are dependent on the influx of extracellular calcium. Human obstetricians routinely use oxytocin as a continuous-rate infusion, with several protocols well described in the literature.
There is evidence in acnine that mothers given higher rates of intravenous fluids have a shorter duration of labor and decreased need for oxytocin administration. An anxious dam that is voluntarily inhibiting uterine activity may caninee a special challenge. If stable, these patients may be placed in a quiet, dimly lit, comfortable room with their owners while their labor is managed veterinary staff should check on the dam and owners every 15 to 20 minutes.
If the clinician believes the dam is excessively agitated, low doses of a sedative, such as an opioid or a benzodiazepine, may be given to facilitate the labor process.
Intrapartum monitoring of the fetus and uterine activity allows the clinician to better medically manage labor and dystocka the need for early surgical intervention. Human medicine sets the standard for the monitoring of uterine activity and fetal physiologic variables. Current monitoring tools available to the veterinarian include B-mode ultrasonography, Doppler fetal heart rate ultrasonography, and tocodynamometry, which can detect changes in intrauterine pressure.
How to Manage the Bitch with Dystocia – BSAVA – VIN
The duration of stage 2 labor has been shown to affect outcome. Gaudet 11 found that the puppy mortality rate increased when the dam had been in stage 2 labor for longer than 6 hours before veterinary assistance was sought. Darvelid and Linde-Forsberg 12 identified an increase in puppy mortality rates from 5. These studies support the efficient and timely management of dystocia cases to reduce neonatal mortality rates.
The Box lists the indications for an immediate cesarean section. The veterinary literature has yet to critically evaluate these indications, and further study in this area may elicit a more precise protocol to improve postoperative outcomes for the dam and puppies. Once the decision to perform a cesarean section has been reached, surgery should be performed in a timely manner. Owners should be counseled about the risks of surgery to the dam and neonates and asked whether they would like the dam spayed during the cesarean section.
Abnormalities in the previously obtained blood work that remain after medical management should be addressed while preparing the patient for surgery. Calm and gentle handling of the dam is also advocated to minimize excitement and catecholamine release, which decreases uterine blood flow and can contribute to fetal hypoxia. Investigators failed to identify any change in systemic arterial blood pressure regardless of position in small- medium- 31 and large-breed bitches 32 up to The unique physiology of the pregnant patient guides the clinician in selecting the most appropriate anesthetic protocol for both the dam and the fetus.
Pregnant dams have decreased lung volume, decreased functional residual capacity, and increased oxygen consumption, which predispose them to arterial hemoglobin desaturation and lung atelectasis. Because the fetus is subjected to any anesthetic agent administered to the dam, and because all drugs that cross the blood-brain barrier can cross the blood-placenta barrier, 33 the clinician should administer as little anesthetic as possible.