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Cesarean section in the bitch: Why mine is different from yours (Proceedings)
For the committed dog breeder, what begins with a single pet as a casual hobby evolves into an avocation that is truly life-transforming. Often their every minute and dollar are expended in pursuit of their chosen "dog sport:"
For the committed dog breeder, what begins with a single pet as a casual hobby evolves into an avocation that is truly life-transforming. Often their every minute and dollar are expended in pursuit of their chosen "dog sport:" AKC or UKC conformation shows, hunting, tracking, agility, water rescue, schutzhund, to name but a few. The average purchase price of a well-bred, registered puppy is well over $1200. Prices for so called "show prospects" can be significantly higher. Stud services vary tremendously in cost but generally start at $500. I recently performed a surgical insemination in which we used a single straw of frozen semen. The bitch owner informed us that he had paid $15,000 for that straw of semen. In addition to the stud service fees, the bitch owner also incurs veterinary service fees for breeding management, semen collection and processing, in addition to FedEX or UPS shipping fees, and travel expenses,etc. Consequently, the dog breeder requires and expects the best possible outcome for each litter.
This section might just as well be entitled, "Please don't shoot your breeder client." Almost without exception, when we see a breeder client for the first time each has their own tale of woe regarding a "nightmare" experience with a caesarian section delivery. The one that is at the top of the list of lasting impressions was related to me by a breeder of springer spaniels. Ten puppies were imaged on her bitch, Emily's, term gestation radiograph. When her Emily failed to progress during labor, she ended up at an EVC for an emergency c-section delivery. One doctor and one technician were on duty at the facility. What follows is an excerpt from her written account of the experience.
"Because Emily was still stable (but exhausted and distressed), there was a lengthy delay in getting her into surgery. As they took her away from me, the doctor said "You don't expect these puppies to be alive do you?" After another hour of waiting, I headed down the hall to the surgical area to see what was going on or holding up the show. The door to this room has a side window next to it. I was shocked at what I saw through that window as I came down the hallway. The tech was putting puppies into the big slop surgical bucket on the floor! I couldn't see that they had even pulled the sack off their faces, no forceps used on the cord or for the placenta. I could only see the handing of the puppies to the tech for her to plop in the bucket on the floor. I tried to open the door as I have to say I was furious. It was locked so I knocked on the window and said "WHAT ARE YOU DOING! GIVE ME MY PUPPIES NOW!"
The point is that many breeder clients perceive that they have been judged negatively by veterinarians for being dog breeders. They also perceive that many veterinarians do not have any idea of the investment they have made in the breeding. Often they do not trust the attending veterinarian, and often this lack of trust is justifiable from their previous experiences with our colleagues.
If you commit to providing services to a breeder client, the following tips may be helpful:
• Be patient. You know you know what you are doing, but they need to be confident that you do know what you are doing. Take the time to answer their questions and "pass the test" without getting your feathers ruffled.
• Be available. If you commit to performing an elective caesarian section delivery or providing intervention in the event of a dystocia, then make good on your commitment.
• Be willing to learn from your breeder clients. I tell my clients that I know canine reproduction, but that I also rely upon them to inform me of predispositions that we may encounter relative to breed or familial lines. Once the breeder client realizes that you respect their knowledge and experience, then they will respect you.
• Involve the breeder client as much as you can. Your patient is much more than their family pet. The breeder client rarely will leave the building when their dog is undergoing surgery, particularly a Caesarian section. Embrace their desire to help. Notably, breeder clients are often adept at puppy resuscitation.
When you perform a caesarian section delivery for a breeder client, the surgery is the culminating event of a well thought out and much anticipated breeding. This is the case whether the surgery is planned or as a result of dystocia. The breeder client has infested as much as $20,000 and hundreds of hours of time in planning the breeding, traveling to parts unknown or having semen shipped in from parts unknown to get the breeding done, and getting their bitch through gestation to term. The goal of the section is not to just get the bitch through the procedure, as would often be the case with a pet female that just happened to get pregnant. For the breeder client, a successful caesarian section delivery must conclude with:
• The bitch stable, alert, ambulatory, and able to able to perform her duties as the dam of her litter. The dam's mothering duties include being able to lactate and provide nutrition to her puppies, to maintain the body temperature of the puppies who are themselves, unable to thermoregulate, and to stimulate elimination of urine and feces in the puppies.
• All of the puppies delivered, resuscitated and successfully nursing. The one puppy that is not revived successfully would have been their "best in show" puppy.
• The future reproductive potential of their bitch preserved.
A successful Caesarian section is the result of a well orchestrated team effort. Close coordination of the surgeon, anesthetist, and nursing staff is critical. Good preparation of the dam, correct selection of the anesthetic protocol, efficient surgical procedure, rapid delivery of puppies, rapid recovery of the dam and adequate neonatal care are the keys to success.
Indications for an elective Caesarian section
Compared to most general practices, our theriogenology service schedules many more elective sections. The indications for elective caesarian section delivery include:
• Dam's breed requires obligatory sections (English and French bulldogs)
• Dam has a history of dystocia requiring surgical intervention
• Dam has an anatomic anomaly which prevents vaginal delivery of puppies
• Litter is very large and may put the dam at risk for a secondary uterine inertia
• Litter is small and the puppies over-sized
• Dam is primiparous but has a familial history of dystocia
• Dam is primiparous and ≥ 6 years of age
• Owner-related factors:
• Owner has concerns about his or her ability to whelp the litter
• Owners lives remotely with limited access to after-hours care
• Owner is concerned about the prospect of going to an EVC for an emergency section, should the need arise.
Owners are counseled about the risks to both the dam and neonates if the surgery is, or is not performed. The final decision on a planned caesarian section involves cooperation and extensive discussion between the bitch owner and the clinician.
When is the Caesarian section scheduled?
Elective c-sections are prospectively scheduled for the day prior to the anticipated parturition date. Therefore, every effort must be made to accurately determine parturition date. The best way to do this is through prospective breeding management, including ovulation timing. Novice breeders will often assert that they need not make the investment in ovulation timing because they own the sire and the breeding will be conducted by natural service mating. In such cases, it helpful to point out that the compelling reason for performing ovulation timing is to accurately determine the day (not the week) of parturition.
Parturition date can be calculated by one of the following methods:
• 65 days from the LH (luteinizing hormone) surge
• 63 days from ovulation
• 57 days from the onset of cytological diestrus
• 37 days from measurement of a 1.2 ± 0.1 cm diameter gestational sac, which usually occurs 26 days post-ovulation. [Personal communication, Will Schultz, Schultz Veterinary Clinic, Okemos, MI, www.schultzvetclinic.com.] Dr. Schultz schedules his ultrasound examinations 23 days after breeding.
In the absence of prospective planning, daily serum progesterone measurement has been used to determine the date for the caesarean section. Reportedly, progesterone levels fall below 1-2 ng/ml 24-48 hours prior to parturition. However, not all bitches read the textbook; it has been demonstrated that some bitches have delivered puppies prior to their serum progesterone levels falling to baseline. Indeed, bitches had delivered puppies in the face of progesterone levels as high as 5 ng/ml.
Under normal circumstances, an elective caesarian section can safely be performed 1 to 2 days prior to an accurately calculated date of parturition. As a final note, it is important to ensure that the bitch is, in fact, pregnant prior to scheduling the surgery. Breeder clients will, on occasion, assert that their bitch is pregnant because she "has all the signs," when in fact their bitch is experiencing a pseudocyesis (false pregnancy).
Preparing for the Caesarian section
Preparatory efforts are directed at minimizing the anesthetic and surgical risks to the dam and fetuses. Maternal stress is detrimental to the fetuses. Care is taken to avoid exposure of the dam to physical stress, pain, or anxiety-provoking situations.
Approximately 2 to 3 days prior to the surgery, the bitch is scheduled to come into the hospital for a pre-operative physical examination, blood work and a term gestation radiograph. Physiologic anemia due to blood volume dilution during term gestation is usually present. Blood work includes clotting tests because bitches, on rare occasion, may exhibit platelet dysfunction. At the pre-operative visit, the hair on the ventral abdomen at the surgical site is removed with clippers. The hair on the dorsal aspect of both antibrachii overlying the cephalic veins is also clipped in preparation for catheter placement. Term radiography is performed to determine the number of puppies present. It is important to know puppy number so that sufficient technical staff members can be scheduled for resuscitation of the puppies. We recommend having at least one technician for every 2 puppies.
A precautionary note regarding pregnant bitches undergoing treatment for luteal insufficiency; bitches that are receiving exogenous progestogen therapy will not demonstrate a decrease in serum progestogen until therapy is discontinued. In such cases, timing of progesterone withdrawal is critical for the well-being of the puppies. Administration of progesterone is discontinued two days prior to delivery date.
The owner is instruction to withhold all food for 9 hours prior to surgery.
The dam is administered prednisolone sodium succinate [Solu-Delta Cortef®, Pfizer] at a dose of 10 mg/kg given intravenously 2-8 hours before surgery. Administration of this short-acting corticosteroid stimulates the term gestation drop in serum progesterone, prevents shock development, and stimulates surfactant production in neonates. The use of methylprednisolone is essential when ovulation timing was not performed prospectively and the precise parturition date cannot be accurately determined.
Just prior to surgery, the fetuses are monitored via ultrasonography. Conventional ultrasound machines allow imaging of fetal hearts; fetal heart rates can be counted visually. Doppler ultrasound units offer an accurate, lesser expensive option for fetal heart rate determination. Fetal heart rate determination by Doppler ultrasound also offers the advantage of being easy and simple to perform. Fetal heart rates are normally > 200 pbm (beats per minute). Normal fetuses may experience transient decelerations down to 180 bpm. Fetal heart rates consistently < 180 bpm are indicative of fetal stress and fetal heart rates consistently < 160 pbm means that fetuses are compromised and required immediate intervention. Comparison of multiple fetal heart rates can aid identification of an abnormal or compromised fetus. An attempt can be made to localize the at-risk puppy to either the left or right uterine horn as well as identify its relative (birth order) location within the horn. Then, the initial hysterotomy incision can be made overlying that puppy so that it can be the first puppy delivered.
The dam's physiology is altered during pregnancy. Physiologic that occur with advanced pregnancy include increased maternal blood volume and cardiac output, and decreased vascular resistance. Respiratory rate is usually increased, and tidal volume may be decreased due to the pressure of the gravid uterus on the diaphragm. Anesthesia may further aggravate the reduction in tidal volume.
During pregnancy, the gastrointestinal system is also affected; there is decreased gastric pH, delayed gastric emptying, and reduced gastric muscle tone (including sphincter tone). Together, these factors may increase the likelihood of vomiting or regurgitation with the potential for aspiration of acidic stomach contents into the respiratory system. Protection of the airway with a relatively rapid induction followed by endotracheal intubation with a cuffed tube is indicated in most cases.
Placement of an intravenous catheter is a must. Intravenous fluid therapy is indicated with all anesthetic protocols in order to manage vasodilation and hypotension. The catheter becomes a veritable lifeline for rapid correction of a precipitous drop in blood pressure which can often occur after the rapid delivery of puppies and the accompanying loss of a large volume of fluid in a short amount of time. During anesthesia and dorsal recumbency, venous return may be impaired by drugs which produce vasodilation and by pressure on the caudal vena cava. Thus, cardiac output may be impaired, leading to reduced blood pressure and impaired tissue perfusion. Removal of the gravid uterus from the abdomen during surgery may promote hypotension due to a decrease in the pressure on the abdominal vasculature, potentially leading to a dramatic reduction of blood pressure. Therefore, fluid loading of the dam during the pre-surgical period is recommended. For the average patient, administer 5 mg/kg of a crystalloid solution in intravenously prior to exteriorization of the gravid uterus.
Pre-oxygenation of the dam prior to anesthetic induction is important for prevention of fetal hypoxemia. Most patients tolerate having an induction mask (with the black rubber diaphragm removed) placed over their muzzle. A 5 to 10 minute pre-oxygenation period is recommended.
A perfectly safe anesthetic protocol for caesarian section delivery of puppies does not exist. Almost all anesthetics and adjunctive drugs cross the placenta to a variable degree depending on lipid solubility, protein binding, molecular size, and concentration gradient. Because drugs administered to the dam reach the neonate, it is prudent to use small doses and to use drugs that neonates are capable of exhaling, metabolizing, or excreting. An anesthetic protocol is chosen which minimizes negative cardiorespiratory effects on the bitch and fetuses. Since most injectable and inhaled agents cross the placental barrier, desirable characteristics of an anesthetic agent include rapid and short duration of effect, titratability, and reversibility. In addition, by using multimodal, combination anesthetic and analgesic techniques, the total amount and negative effect of each agent can be reduced.
Considerations also include the need for rapid anesthetic induction, minimal respiratory and cardiac depression, rapid recovery and no lingering side effects. It is important to maintain the physiological status of the dam throughout anesthesia—avoiding hypotension, hypovolemia, hypoxemia, and hypercarbia. Because of the amount of abdominal pressure placed on the diaphragm, many surgeons advocate the use mechanical ventilation on all caesarian section procedures regardless of the patient's ability to ventilate.
There are many options available for anesthesia. The best protocol is the one with which you are most comfortable. There are, however, a few drugs that should be avoided. Phenothiazines, barbiturates, ketamine, tiletamine HCl/Zolazepam HCl (Telazol) and alpha-2 agonists (xylazine, metdetomidine) can all pass through the placenta and can affect the ability of neonates to thrive. Ideally, they should not be used.
Pre-medication with chronotropic agents prior to anesthetic induction is controversial. Atropine crosses the placental and enters fetal circulation, while glycopyrrolate does not cross the placenta. Advocates for the use of atropine maintain that it will aid in preventing bradycardia in the fetuses. Opponents believe that it exacerbates hypoxemia in fetusus.
From Grundy "Clinically Relevant Physiology of the Neonate" Vet Clin NA 2001:
• Despite evidence of structural parasympathetic maturity, chronotropic responses in puppies at any given level of neural stimulus are less as compared with adult dogs, and before 14 days of age, there is minimal increase in heart rate in association with atropine administration, suggestive of a lack of vagal tone. In kittens, vagal stimulation was found to have no effect on heart rate until 11 days of age. These findings suggest a lack of full cardiac autonomic development during the neonatal period and help to explain why atropine is not effective in neonatal resuscitation. One of the most important considerations of cardiovascular physiology in the neonate is that bradycardia is not vagally mediated and is indicative of hypoxemia in the fetus and during the first 4 days of life. Although the neonate seems to be able to resist circulatory failure to a greater extent than the adult animal during this time, it is far more appropriate to supplement oxygen than to give parasympatholytic agents, such as atropine, the administration of which only exacerbates cardiac hypoxemia via increasing oxygen demand in the face of hypoxemia.
Opioids provide good analgesia in the dam. Their use is also controversial. Proponents maintain that although they have some depressive effects on the fetuses, they are easily reversed in neonates. Opioids with a prolonged duration of action should be avoided prior to delivery, as they may outlast the reversal effects of naloxone. Therefore, short-acting opioids are a better option for pre-operative use, whereas longer-acting opioids may be more appropriately used to provide analgesia in the post-operative period.
Anesthetic regimens that are commonly used for caesarian section can be included in one of the following categories:
• Epidural analgesia with or without sedation,
• Sedation and infiltration of the abdominal midline with local anesthetic
• General anesthesia with injectable drugs and/or inhalants.
Epidural analgesia with sedation
The primary advantage of epidural analgesia is minimal depression of the neonates. Epidural analgesia at the lumbosacral junction, using 2% lidocaine, provides a rapid onset of analgesia (usually less than 10 minutes) and an adequate duration of analgesia (1.5 to 2 hours) to facilitate the surgery. Sedation and subcutaneous administration of a small amount of lidocaine (0.25 to 0.5 ml of 2% lidocaine) subcutaneously over the lumbosacral space, prior to placing the spinal needle, facilitate epidural technique and promote the dam's acceptance of dorsal recumbency during surgery. Two per cent lidocaine provides analgesia to the level of the first lumbar vertebra if administered at a dose of 1 ml per 10 pounds (usually adequate for a simple caesarian section without ovariohysterectomy), and to the level of the fifth thoracic vertebra if administered at a dose of 1 ml per 7.5 pounds of body weight.
Several factors should be considered when selecting epidural analgesia:
• Obesity in the dam is an indication for using a smaller dosage of lidocaine.
• Over-dosing lidocaine can lead to respiratory depression, cardiovascular depression, and neurological sequelae.
• Epidural lidocaine causes vasodilation in the affected part of the body, possibly leading to hypotension and/or hypothermia.
• Aseptic technique should be used for placement of spinal needles to avoid contamination and infection in the spinal canal.
• Poor technique with a spinal needle can lacerate and damage the spinal cord.
• The technique of placing spinal needles requires practice, and some patients are more difficult (e.g., obese animals, animals that have had pelvic trauma).
• Patients should be monitored for adequate ventilation and adequate vascular volume, and preparation to manage abnormalities should be made in advance.
• Some patients move spontaneously (not associated with pain) during sedation and epidural analgesia. Thus, an assistant may be needed to control patient movement or administer an additional amount of sedative.
Local infiltration of the ventral midline with sedation
Usually, the dam is heavily sedated with an opioid or an opioid-tranquilizer combination. Then, the ventral midline is infiltrated subcutaneously with a local anesthetic over the distance of the expected incision site; lidocaine is commonly used because of its rapid onset of action and adequate duration. Two to three mg per pound total dose of lidocaine avoids toxicity while providing an adequate volume for infiltration. Dilution of 2% lidocaine with sterile saline to produce a 1% solution can be done if a larger volume is needed to assure adequately blocking the surgical site. This technique is not an appropriate choice if the dam is to be spayed at the time of the caesarian section; analgesia may be inadequate for excision of the ovaries.
General anesthesia is often preferred for caesarian section delivery due to its ability to provide complete analgesia and immobilization. The main disadvantage to general anesthesia is exposure of the fetuses to anesthetic agents and the potential for depression of the fetuses and the bitch. General anesthesia for caesarean section can be accomplished by numerous combinations of preanesthetic medications, induction drugs, and maintenance anesthetics. Choices are often dictated by experience as well as by the expected effects of the drugs used.
Numerous induction options exist. Propofol is a good choice as an anesthetic induction agent. Propofol, a rapid acting, short duration, injectable anesthetic agent, permits immediate orotracheal intubation and control of the airway. It can be administered as a constant rate infusion, and used in combination with low percentage rates (≤ 1%) of sevoflurane or isoflurane (shorter-acting gas anesthetic agents, which are not metabolized but exhaled during ventilation).
Propofol does cross the placenta, but rapidly crosses back, and is also quickly metabolized even with immature livers. Puppies seem to awaken readily after delivery when propofol has been used to induce anesthesia in the dam. Anesthesia can also be induced by mask with an inhalant, and sevoflurane and isoflurane offer two effective options. Because of faster recovery, sevoflurane has gained popularity as an inhalant for caesarian section. If a mask induction is used, careful attention to the airway is essential, and the possibility of regurgitation and aspiration with an unprotected airway should be weighed against the advantages of an entirely inhalant protocol.
Maintenance of general anesthesia for caesarian section is usually accomplished with an inhalant—isoflurane may be more commonly used in veterinary practices. However, sevoflurane has a low blood:gas partition coefficient (low solubility in blood); it is known for fast inductions, fast recoveries, and rapid control of depth, does not irritate the mucous membranes and is a logical choice for caesarian section. Even though sevoflurane crosses the placenta, neonates seem to be able to exhale the drug efficiently. The best practice is to administer the lowest possible amount of sevoflurane to the dam until the neonates have been delivered. This can be facilitated by a ventral midline infiltration with a local anesthetic. Some veterinarians use small doses of propofol to minimize the amount of inhalant anesthetic required to maintain the dam until the uterus is exteriorized, thus reducing the amount of inhalant reaching the fetuses. Neonates should be delivered as quickly as possible. After delivery, attention to the neonates should include clearing the airway, physical stimulation, oxygen, and attention to heart rate and breathing. After delivery is complete, the surgery on the dam can be completed with usual amounts of sevoflurane.
Regardless of the anesthetic regimen chosen, patient monitoring is instituted in every case. A caesarian section surgery, with its rapid, obligatory changes in the patient's circulating fluid volume and blood pressure, demands careful attention to be paid to the patient's vital signs. Early detection of any life threatening status is paramount to the timely and successful correction of the problem. Parameters monitored include body temperature, blood pressure, electrocardiography (ECG), pulse oximetry, tidal volume and end tidal capnography.
Following anesthetic induction, endotracheal intubation and placement on sevoflurane inhalant anesthesia, the bitch is placed in dorsal recumbency. Preparation of the surgical area is completed concurrent with application of patient monitoring equipment. Parameters monitored throughout surgery include electrocardiograph (ECG), heart rate, respiratory rate, tidal volume, blood pressure, pO2, and pCO2. Monitoring is essential because the potential for a precipitous drop in blood pressure is great during the procedure. Lubricant is placed in the eyes to prevent corneal drying. Hot water bottles wrapped in towels are placed next to the patient to aid in combating the effects of heat loss during surgery. Do not place patient on an electric heating pad. During delivery, chorioallantoic fluid may pool dependently under the patient, thereby increasing the risk of thermal injury or electrocution.
After induction and prior to delivery of the first puppy, the patient is pre-loaded with warm, sterile colloidal fluids such as hetastarch at a dose of 1 ml per 10 pounds of body weight intravenously. A synthetic polymer derived from a waxy starch, hetastarch is composed primarily of amylopectin. To avoid degradation by serum amylase, hydroxyethyl ether groups are added to the glucose units. It has an average molecular weight of 450,000, but ranges in size from about MW 10,000-1,000,000. Hetastarch occurs as a white powder. It is very soluble in water and insoluble in alcohol. Hetastarch may also be known as hydroxyethyl starch or HES. Hetastarch acts as a plasma volume expander by increasing the oncotic pressure within the intravascular space similarly to either dextran or albumin. Maximum volume expansion occurs within a few minutes of the completion of infusion. Duration of effect is variable, but may persist for 24 hours or more. Hetastarch is is available as a 6% (6 g/100 ml) solution in 0.9% sodium chloride, in 500 ml IV infusion bags; Hetastarch (Gensia Sicor Pharm).
The recommended surgical approach for a caesarian section in the bitch starts with a ventral midline incision from the umbilicus to the pubis. Use of electrocautery or radiosurgery to simultaneously cut and coagulate vessels encountered facilitates rapid entry into the abdominal cavity and decreases blood loss due to hemorrhage. The subcutaneous vasculature is highly developed in the term pregnant state. Without cautery, many hemostatic forceps may be required to control hemorrhage from these vessels. Therefore, use of cautery also reduces the risk that a hemostatic forceps might inadvertently be left behind in the abdominal cavity.
Care should be taken to identify the linea alba. The linea alba will likely be very thin, due to stretching of the abdominal musculature and fascia. Failure to enter the abdomen through the linea alba will result in two deleterious consequences, more hemorrhage from the abdominal muscles and more hemorrhage and milk seepage from the mammary glands into the wound. Care should be taken to ensure that no underlying abdominal organs are incised during initial entry into to the abdomen. This can be accomplished by lifting the linea and orienting the scapel blade with the cutting edge directed ventrally for the initial stab wound through the linea.
The uterus is isolated and exteriorized from the abdomen using moistened laparotomy pads or towels. Warmed, sterile crystalloid fluids are used for wetting agents. The abdominal wall incision should be extended as needed. The highly dilated uterus is extremely fragile and presents a significant risk for rupture. Care must be taken to manipulate the uterus gently. To improve relaxation of ovarian pedicles and facilitate exteriorization of the uterus, 0.5 to 2 ml of lidocaine is applied to the ovarian suspensory ligaments. This also dramatically reduces postoperative pain potentially associated with traction on the pedicles. Moreover, traction on ovarian pedicles may induce a vagal reflex, leading to hypotension and bradycardia; lidocaine helps prevent such a reflex. If the uterus is difficult to exteriorize through the abdominal opening, the length of the opening is likely insufficient. A tear in the uterine wall can be the consequence of forcing the uterus through too small an opening. With large litters, the uterus can be exteriorized one horn at a time. Moistened laparotomy pads are placed under and around the uterus to reduce leakage of uterine contents in to the abdomen. This is particularly important if the uterus is suspected to contain infectious agents.
Most published sources recommend making a single dorsal midline incision into the uterine body. Recently, an alternative entrance into the uterus has gained popularity. Two separate, as opposed to the traditional single, hysterotomy incisions are made, one in each uterine horn, midway down the length of the horn. Midhorn hysterotomy placement facilitates rapid removal of puppies and avoids a lengthy "milking" process for puppies located in the tip of each uterine horn. Rapid delivery of puppies increases their survival. The disadvantage of two incisions into the uterus is that surgical time for uterine wound closure is doubled.
When incising the uterus, care is taken to avoid inadvertent laceration of an underlying puppy or placenta. Placental lacerations can sometimes bleed profusely. As each puppy is removed from the uterus, the surgeon tears the fetal membranes overlying the puppy's head and wipes the muzzle removing membranes and amniotic fluid from the nostrils and lips. The puppy is held with its head in a dependent position to allow escape of fluid from the airways. This "head down" position is maintained while the puppy's umbilical cord is double clamped with two small mosquito forceps. At least 2 cm of umbilical cord should be present between the abdominal wall and the nearest forceps. The umbilical cord is incised between the two forceps. No time is expended in removing placentae during delivery of puppies. Each puppy is placed in a sterile hux towel and handed off (in "puppy taco" fashion) to a technician for continued resuscitation. Care is taken to avoid tension on the umbilical cord between the forceps and the abdominal wall, and subsequent iatrogenic umbilical herniation.
After all of the puppies in the first uterine horn are delivered, a second hysterotomy incision is made midlength in the contralateral horn. All puppies in the horn are delivered. As the last puppy is delivered, a dose of methergine® (methylergonovine maleate) is administered to the dam. Methergine is a semi-synthetic ergot alkaloid used for the prevention and control of postpartum hemorrhage in the human. Methergine is available from Novartis in sterile ampuls of 1 mL, containing 0.2 mg methylergonovine maleate for intramuscular or intravenous injection and in tablets for oral ingestion containing 0.2 mg methylergonovine maleate. Methergine acts directly on the smooth muscle of the uterus and increases the tone, rate, and amplitude of rhythmic contractions. Thus, it induces a rapid and sustained tetanic uterotonic effect which shortens the third stage of labor and reduces blood loss. The onset of action after I.V. administration is immediate; after I.M. administration, 2-5 minutes, and after oral administration, 5-10 minutes. The most common adverse reaction reported in humans is hypertension associated in several cases with seizure and/or headache. When given to the bitch, methergine is administered at a dosage of 0.1 ml per 20 pounds body weight IM or very slowly (over 1 minute) IV.
After initiation of uterine involution with methergine, the uterus is carefully inspected in its entirety, from ovary to ovary and then palpated into the pelvic canal, to ensure that all puppies have been delivered. Oxytocin is administered (1-4 IUs per dog) IV to the bitch to promote further uterine involution and milk let down. Do not overdose oxytocin.
Once the pups have all been delivered, analgesic agents can be administered to the bitch. Pure agonist opioids such as buprenorphine, hydromorphone or oxymorphone are good choices. Prior to uterine wound closure, fetal membranes exterior to the uterine wall are clamped and trimmed. Usually hemorrhage is minimal and ligation of the membranes is not necessary so long as a placenta proper has not been lacerated. The hysterotomy sites are closed with a 3-0 or 4-0 absorbable, monofilament suture material on a taper needle using a single layer, double inverting suture pattern. A two layer closure is usually not necessary unless the uterine wall is compromised. Care is taken to avoid placement of sutures into the uterine lumen, fetal membranes or placentae. Knots are buried to reduce adhesion formation.
Following hysterotomy wound closure, the uterus and mesometrium are lavaged with warm saline or lactated ringers solution and carefully inspected a final time. Delivery of all puppies is confirmed. Any tears present in the broad ligament are sutured. The uterus is placed back into the abdomen taking care to reposition the horns to their normal site. If the abdominal cavity has been contaminated with fetal fluids, it should be lavaged with warm saline prior to closure.
The abdominal cavity is then closed in routine fashion in 3 layers. The linea is closed with 2-0 to 1 absorbable, monofilament suture such as PDS or monosorb in a simple, continuous suture pattern. Several simple interrupted sutures are evenly spaced and placed along the suture line in a "spot weld" fashion. The subcutaneous layer is closed with a finer gauge (3-0 or 2-0) absorbable,suture material in a simple continuous pattern. The linea and subcutaneous tissues along the length of the incision line are then infiltrated with bupivacaine 0.5% solution. Total dose of bupivacaine used should not exceed 1 ml per 10 pounds of body weight. Often, the bupivacaine is diluted 1:1 with sterile fluids to provide sufficient volume of solution for infiltration of the entire incision line.
Wound closure is completed with a subcuticular layer of absorbable sutures in a simple continuous pattern. Often a softer, braided suture material such as vicryl plus is chosen for this layer. Skin edges are then apposed with thin layer of surgical glue to seal the wound. Skin sutures and staples are avoided to reduce the risk for entrapment of milk, saliva, urine or feces in the sutures.
Anticipating potential complications
The two most common maternal complications experienced during Caesarian section delivery are hypotension and hemorrhage. Intra-operative hypotension requires an investigation into the patient's anesthetic depth, PCV/TS, glucose, electrolytes, and venous blood gas. Abnormalities are rapidly corrected. Excessive hemorrhage from the placental sites can occur, requiring blood transfusion, administration of a hemoglobin-based oxygen carrier, and/or rapid ovariohysterectomy (OHE). It is important that the necessary products be on hand and ready to use should the need arise. In a dire situation, there may not be sufficient time to perform blood collection from a donor dog.
Resuscitation of puppies is initiated with the surgeon. As the puppy is delivered, it is held with its head in a dependent position to promote passage of amniotic fluid out of the respiratory tract. Using a hux towel, the surgeon wipes the muzzle and oral cavity to remove any fluid present. The puppy is maintained in a head down position while the umbilical cord is double clamped and incised between the clamps. Then the puppy is placed in a sterile, dry hux towel and handed off to an assistant for continued resuscitation.
The oral cavity of the pup is suctioned free of amniotic fluids and any remaining fetal membranes using a Delee mucus trap [sterile 8 Fr, transparent 20 cc trap, graduated in 2 ml, Medline Industries] or bulb aspirator and/or a gauze sponge. Swinging the pups to force out fluids from the airway is not recommended because of the risk of neurological trauma. Oxygen is administered via face mask while the puppy is stimulated by rubbing with a clean, warm towel. An oxygen concentrator can concentrate oxygen from 21% at room air to >93%, and provides an inexpensive means of oxygen delivery when a second anesthesia machine is not available for oxygen administration. The puppy is warmed and the warmth is maintained with warm towels, hot water bottles and Snuggle Safes™. If an electric heating pad is used, it should be set on a low setting. Care needs to be taken to avoid over heating or chilling of puppies. When puppies are noticeable chilled, submerging of the puppies in warm water (up to their heads) followed by blow drying has been advocated as a means of rapid warming.
If the pup is not ventilating spontaneously, it can be intubated using any type of catheter or tube. Orotracheal intubation is facilitated by placing the pup in dorsal recumbency and using a laryngoscope with a neonatal blade. Ventilation is performed using 100% oxygen set at 3-5L/min flow rate, and intermittently attaching the end of the oxygen tubing to the catheter hub. Care must be taken not to overinflate the puppy's lungs. Depending on the level on anesthetic acting on the puppy, ventilatory efforts may be required for several minutes before the puppy begins to breathe spontaneously.
The use of acupoint GV 26 for resuscitation and stimulation is widely practiced. Special training and needles are not required for success, as the point, located midline on the philtrum at the junction of its dorsal and medial third, is readily accessed and a 25 g needle can be utilized. Stimulation is provided in a strong manner, with a pecking motion. Stimulation of GV 26 increases blood pressure and stimulates the brain inspiratory centers.
One long standing "must do" procedure for puppy resuscitation has recently become extremely controversial. Many of us learned the "drop of doxapram under the tongue" technique and considered it gospel. Interestingly, there are no published studies that even look at absorption from this route. So we don't know if it is even functional when given this way. Injection under the tongue often results in dramatic tissue sloughing and should not be used at all. More importantly, we now know that doxapram is NOT an appropriate drug to use unless the neonate is being vigorously oxygenated and ventilated via endotracheal intubation.
Doxapram is believed to work via both central stimulation and stimulation of the carotid chemoreceptors. It is not effective unless the brain is oxygenated. It also can decrease cerebral blood flow. It is no longer used at all in human neonatal resuscitation. Doxapram should be used only if the neonate is receiving oxygen, and it should not be administered sublingually. If indicated,doxapram can be administered via the umbilical vessels (which were clamped about 2 cm away from the body wall).
If no heart beats can be palpated or asculted, or the rate is very slow, gentle transthoracic cardiac massage is started. Oxygenation of the puppy should already be in progress. If a narcotic was administered to the bitch/dam, naloxone can also be administered intralingually. An umbilical or intraosseous catheter may be placed for drug administration if necessary. In most neonates, cardiac massage is best done via lateral compressions. In some barrel-chested breeds, it may be more useful to use a D-V compression. Compressions should NEVER take the place of ventilation. Hypoxia is the neonate's biggest problem and puppies must be intubated and ventilated at once. If, after the neonate is intubated, oxygenated, ventilated, warmed, stimulated cardiac massaged and still has no heartbeat, then epinephrine will be administered. Again, we will use the umbilical vein for access. Epinephrine will increase mean blood pressure and improve myocardial oxygen delivery. There are controversies about dosage, but doses typically start at 10 ug/kg IV and can be increased if there is no response.
Atropine was once commonly used, if no heartbeat or if bradycardia was noted. Once again, we must realize that bradycardia in the neonate is essentially always due to hypoxia. Hypoxia in the neonate is due to direct depression rather than vagally mediated, so atropine is not useful. We must intubate and ventilate the neonate to ensure appropriate oxygen delivery occurs. Atropine is actually contraindicated in this instance, as it will increase the myocardial oxygen demand and make things worse for the neonate. Bradycardia can be drug induced, and in that case the antidote can be administered via the umbilical vein (ex: naloxone if due to narcotic).
Once puppies are "beatin' and breathin'" spontaneously and exhibit good perfusion parameters, then the umbilical cords are ligated about 2 cms away from the body wall. With the ligature thus placed, access to the umbilical vessels is permitted should drug administration become necessary. Betadine solution is applied to the end of the umbilical stalk as a disinfectant and drying agent. Each puppy is uniquely identified and weighed. Resuscitative efforts are recorded. If a puppy required more intensive effort to resuscitate then that information should be passed along to the owner. The puppies are placed in a warm environment and are monitored continuously by assistants until the doctor has completed surgery on the dam and can perform an examination on each puppy.
Post-operative care of the dam and neonates
The bitch/dam maintained on oxygen for several minutes following "cut off" of inhalent anesthesia. During this time, the mammae are wiped with a towel moistened with warm water to remove the disinfectant from the nipples. During this process, the mammary glands are evaluated for degree of development and the presence or absence of colostrum or milk. The dam is then placed in a warmed recovery run, covered with warmed blankets and monitored until extubation is performed. Typically, the owner is permitted is sit with the dam during recovery. The patient is maintained on fluid therapy until such time that she is fully awake and assessed to be in stable condition. If excessive hemorrhage, hypoglycemia, hypocalcemia, hypotension, or other systemic illness occurred during surgery, the dam is closely monitored with repeated laboratory and blood pressure evaluation during the recovery period.
The puppies are examined while the dam is recovering from anesthesia. Each puppy is examined carefully to ensure that mucus membrane color is pink and capillary refill time is normal. The thoracic cavity is asculted: heart sounds are checked for normalcy of rate, rhythm and character (murmurs) and the lung fields are checked to ensure that the puppy is free from congestion. Puppies are also examined for congenital defects, such as cleft palate, atresia ani or limb deformities.
Ideally, the dam will be totally awake soon after the procedure. The puppies are placed with her as soon as possible so that the maternal bond can be established. Introduction of the puppies to the dam requires careful supervision. When the puppies are first placed with the dam, an effort is made to get each puppy attached to a nipple and nursing effectively. Sometimes this process can be facilitated by expressing a few drops of milk from the nipple just prior to attachment. Ideally, all puppies have suckled and ingested colostrums prior to being discharged. The dam should be closely monitored for signs of rejection during the initial post-anesthetic period. If she is not lactating within 6 hours, has a systemic illness, or has a prolonged anesthetic recovery, the puppies may require bottle feeding.
The dam and her puppies should be returned to their home environment as quickly as possible to facilitate establishment of the neonatal/maternal bond. Being in the comfort of their own environment reduces postoperative stress and mediates associated behavioral and lactation problems.
• Post-operative analgesics. For post-operative analgesia, tramadol, a synthetic mu-receptor opiate agonist that also inhibits reuptake of serotonin and norepinephrine, is a good choice. Tramadol and its active metabolite enter maternal milk in very low levels, but the drug's safety in neonates has not been established. For post-operative analgesia, the dose is 1-4 mg/kg PO q8-12h. Tramadaol is available as a 50 mg tablet. The use of non-steroidal anti-inflammatory drugs has also come under some controversy because little is known about their effect on the neonatal kidney.
• Antibiotics. An intravenous injection of a cephalosporin (cefazolin) is often administered as the surgeon makes the approach into the abdomen. The decision as to whether or not to prescribed continued antimicrobial therapy is often based upon the amount of spillage of fetal fluids into the abdomen or pre-existence of infectious disease, etc. If antibiotics are continued, it is important to choose a drug that will not have a deleterious effect on the nursing neonates. Generally, cephalexin, amoxicillin and clavamox are good choices in that regard, while enrofloxacin, ampicillin and tetracycline should be avoided.
• Probiotics. Bitches are prescribed a probiotic such as Forti Flora [Purina] to promote and maintain the appropriate resident bacterial flora in the gastrointestinal tract. This is particularly important if the bitch is receiving antimicrobial agents. The probiotic should also be administered daily to the neonates.
• Ecbolic agents. If all of the placentas were not removed at the time of surgery, the bitch is administered a dose of oxytocin (0.5-3 IU/dog SQ) the day following surgery to promote passage of placentas. Oxytocin will also stimulate milk let-down.
• Lactation promoter. Domperidone causes prolactin release and has been used to increase milk supply in women. In rats, it enters milk in small amounts with approximately 1/500th of the adult dose reaching the pups. Domperidone is available as Equi-Tox and is supplied as 25-ml tube apple-flavored paste. With this formulation, the paste is administered 0.1ml/20 pounds po bid. A small animal formulation is available.
• Maternal bonding facilitator. DAP (dog appeasement pheromone) collars placed on the dam may promote formation of the maternal bond. Dog attachment pheromone is a natural chemical found in the amniotic fluid of dogs and is also produced by the lactating mammary gland of the bitch. This pheromone stimulates attachment of the dam to the pups and vice versa. With elective caesarian section deliveries, maternal bond formation to her puppies may be delayed for several days and in some cases, may fail to form altogether. The dam is not exposed to the natural pheromone during the birth process and the problem is compounded by the disinfectant odors that are present. Primiparous bitches, in particular, may fail to attach and effectively mother their puppies. DAP, or dog appeasement pheromone [Ceva Animal Health, Inc., Lenexa KS], is a synthetic version of the naturally occurring pheromone. DAP is available as a collar that lasts up to four weeks, a diffuser, which takes 72 hours to equilibrate in a room, and a spray that dissipates in a couple hours (and contains alcohol. DAP collars can be put on a C-section bitch before she wakes up and kept on her at least until good solid mothering behavior is present.
Following is an example of VSL's written discharge instructions for a Caesarian section delivery:
Congratulations on your lovely new litter of 9 puppies. Bella handled anesthesia very well and her Caesarian section delivery was without complication. We did not observe any significant pathology in her uterus or ovaries at the time of surgery. We believe she should be able to conceive and delivery another litter for you in the future.
Please follow these post operative instructions carefully as it is very important to the health and recovery of both Bella and her puppies. Let us know if Bella experiences any significant post-operative hemorrhage after she is discharged. It is normal to have a little frank, red hemorrhage for the first 24 hours following a Caesarian section delivery. After that, the discharge should turn more brick red in color, appear more like normal post-whelping discharge, and gradually diminish over time. You will see placentas pass and some green/black discharge because the placentas were not removed at the time of surgery. New research has shown that it is better to leave them in the uterus than to take them out if they are not detached already. This greatly reduces the amount of hemorrhage the patient experiences with this procedure.
After two to three weeks, there should be no discharge at all. If, at any time, Bella's vaginal discharge becomes smelly or creamy, please get in touch right away.
Bella's feeding and watering for the first 48 hours following surgery are very important. Her normal digestive process will be slower than normal during this time. So it is very important to feed and water her in very small increments. This is to avoid an episode of bloating. Peristalsis and other digestive processes are slowed for a period of time following any procedure involving sedation or anesthesia. After 48 hours, you may gradually resume her normal feeding schedule.
Please take her temperature twice daily for the first week post-operatively. We would like to be notified if it is higher than 102.5. Because we delivered her puppies prior to the onset of labor, Bella may experience a temperature "drop." She may nest and exhibit signs of crampiness or labor over the next 24 hours.
Please inspect Bella's incision site and gently clean as necessary twice daily. The post operative care of Bella's incision site is crucial for prevention of complications such as infection or non-healing. Baby wipes are good to use for this cleaning. The incision area must be kept clean and dry and free from soured milk. We also want you to check her mammary glands at least twice a day as well. Notify us immediately if a gland becomes painful, hot, swollen, discolored or if the milk has an "off" color or smell.
Also give all medications as directed until gone. Some must be given with food.
For the puppies, please weigh them daily to make sure that they are in a "weight gain" status. If they are not gaining daily, please call so we can figure out why. Neonatal puppies will arouse to nurse on their own every 2 to 3 hours. We would also like to know if they do not appear to be vigorous for any reason.
DO NOT LEAVE BELLA UNATTENDED WITH THE PUPPIES. When puppies are born by Caesarian section delivery, it often takes dams up to 3 days to "decide" that the puppies are not squeak toys, prey items or little aliens. Some new mothers will not willingly allow puppies to nurse. In extreme cases, new mothers can kill their babies in just a few seconds. If you must leave the puppies, even for a moment, please put Bella in a crate and shut the door. Most breeders do not leave the mother and her puppies unattended for the first 7 to 10 days post partum. If Bella is not stimulating the puppies to urinate and defecate, you must take over this task as well.
We appreciate your trust in managing this very important delivery. For the next 3 days, we would like to have a quick call from you just to update us on everyone's condition. Please call anytime if you have any questions or concerns at all. Again congratulations,
Dr. Jane, Star, Suzy, Beth and Jill.
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