What you need to know about the veterinary Caesarean-section patient | VETgirl Veterinary Continuing Education Videos
In this VETgirl online veterinary continuing education video, we review everything you need to know about dystocias and Caesarean-section (C-section) of the veterinary patient. Dystocia refers to the difficulty, or inability to pass a fetus through the birth canal. Dystocia in dogs is defined by prolonged gestation, Stage II labor lasting greater than 24 hours, or greater than 4 hours between puppies. Brachycephlic dogs such as French and English bulldogs are vastly over-represented with rates cesarean section reported of greater than 80%. If you have clients breeding these dogs, it’s worth having a discussion about a planned C-section. Dystocia in cats is less common than in dogs, and accounts for roughly 5% of all cats in labor. Criteria for dystocia in cats includes greater than 4 to 6 hours between birth of kittens, or labor lasting more than 24 hours. Pure-bred cats such as Siamese, Persian and Devon Rex are over-represented compared to domestic short hairs.
In both dogs and cats, protrusion of the fetal membranes and green discharge for longer than 15 minutes also is a criteria for dystocia. Uterine inertia is the most common cause of dystocia and can occur due to litter size or continued contractions with fetal obstruction. An obstructed birth canal may be evident on gentle digital vaginal exam. Rectal exam may also be useful to examine the pelvic canal for narrowing from causes such as pelvic fractures.
It is important to rapidly identify dystocia and proceed with treatment quickly to increase neonate survival. Baseline diagnostics are vital, including bloodwork, radiographs, neonatal ultrasound to determine fetal heart rates and viability, and a digital vaginal exam to stimulate the Ferguson reflex. If uterine contractions are not stimulated by the Ferguson reflex, medical management is likely to be unsuccessful.
If radiographs determine fetal malposition or obstruction, if medical management is contraindicated, if there is fetal distress or fetal death, then Caesarean section is indicated. Ultrasound is less reliable for determining numbers of fetuses and for evaluating fetal malposition but can be useful for evaluating fetal viability and signs of fetal distress as indicated by decreased fetal heart rate. Normal fetal heart rate is 220 beats/min or higher and a fetal heart rate below 150-180 bpm in a non-anesthetized dog or cat is a sign of severe fetal distress.
Anesthesia for C-sections involves walking a line between safety and comfort for the mom and minimal sedation for the puppies so it is important to plan your protocols accordingly. Commonly used medications for Caesarean sections are opioids, such as fentanyl or hydromorphone, in combination with a benzodiazepine, such as midazolam, as these cause minimal respiratory depression in the neonates and can be reversed with naloxone and flumazenil, respectively. Preoxygenate, then induce with propofol or alfaxalone, followed by maintenance with isoflurane gas anesthesia. Line blocks of the skin and linea can be used to decrease the amount of anesthetic gas needed as the gas anesthestics pass easily to the puppies. If you or your anesthetists are comfortable with them, epidural can be very valuable and can often be given under pre-meds to decrease anesthesia amounts and time under anesthesia. Patients should be clipped and prepped as much as possible prior to induction to decrease time of anesthesia.
On the surgery table, tilt the patient slightly to the side to shift the weight of the uterus in order to improve vascular return. When making your ventral midline incision, be aware of engorged mammary vessels and ligate quickly to reduce blood loss. The linea is also stretched and thin and is often in direct contact with the uterus, so incise carefully! Elevate the uterus and make sure the horns aren’t twisted. The uterus can be removed in its entirety if an ovariohysterectomy is elected, then handed off to an assistant to remove each fetus. This is particularly effective and quick if you are using a ligasure device but should only be performed if you have efficient and competent assistants since the puppies will not be getting oxygen from the time of the ligation until the assistants can remove them from the placenta. Alternatively, an incision can be made in an avascular region of the uterine body, or the base of a uterine horn, and each neonate extracted. The fetal sacs can be torn and the placentas gently removed. Be sure to pack off the uterus with lap sponges to reduce abdominal contamination.
The puppies should be handed off to an assistant (Thankfully, it’s not usually difficult to find volunteers to resuscitate puppies!) with the placenta still attached to allow the puppies a little extra time to absorb blood and nutrients from the placenta. Each puppy should ideally have a person to resuscitate it although this may be challenging with large litters. The oral and nasal cavities are suctioned with a bulb suction device. Despite what many of us were taught, puppies should not be slung or swung as this may lead to brain hemorrhage. Poor doer puppies should be revived with flow-by oxygen and vigorous rubbing to simulate a mother tongue. The use of dopram is no longer recommended but reversal of opioids and benzos can be performed if they were used on the mom.
Closure of the uterine body can be routine with appositional or inverting patterns using absorbable monofilament such as PDS, typically in a double layer. An ovariohysterectomy can be performed at this time if elected. Flush the abdomen and inspect for any pathology. Close the abdomen routinely. External skin sutures or staples should not be used as these can injure nursing puppies. Because these dogs and cats usually go home soon after surgery and oral pain meds can be passed to the puppies, Nocita, a long-acting local anesthetic is a great addition to your closure protocol if you have it available.
To improve nursing, clean each mammary gland postoperatively to remove residual disinfectant. Neonates should be resuscitated by drying them off vigorously, reversing any narcotics or benzos, and suctioning nasal or oral secretions. Suture umbilical stumps and provide flow by oxygen. To stimulate breathing, a 25-gauge needle can be used at the acupoint site in the nasal philtrum, level with the lower edges of the nostrils. Epinephrine can be given via injection sublingually, or intraosseously if needed.
Try to get the neonates to nurse as soon as the mom has recovered from anesthesia. Keep the neonates warm and pay close attention to how the mom is treating the neonates, as not all mothers know what to do. In most cases, we try to discharge the mom and puppies within 6 hours or so after surgery to allow the mom a quiet place to care for her puppies. Get them out of the hospital ASAP! Because the effects of most of our pain meds on young puppies is not known, NSAIDs are usually avoided and Tylenol is considered safe for nursing mothers. In summary, dystocia needs to be recognized early and treatment initiated as soon as possible to improve fetal survival.