Introduction

Cesarean section is typically performed in the case of dystocia which cannot be resolved vaginally. This includes live, malpositioned fetus(s) which cannot be mutated to allow delivery, live fetuses that are too large to exit the vaginal canal, or fetuses which have recently died but are too large. Other indications for cesarean section include exhaustion of the dam and uterine inertia, encountered commonly in swine, and failure of cervical dilation, more frequently diagnosed in small ruminants. Although fetotomy is effective for removal of malpositioned, dead fetuses, it may not be rewarding for very large and/or emphysematous dead fetuses. In the case of the latter, multiple cuts are needed as the fetus is removed piecemeal, and frequently results in severe trauma to the dam. There are several approaches for cesarean section depending on the species, animal temperament, and condition of the uterine contents.

Standing Flank Approach

The standing flank approach is the preferred approach for ruminants as it avoids the cost, potential complications, and difficulty of sedated or anesthetized recumbency. This approach may be utilized in cattle as well as small ruminants. The left paralumbar fossa is preferred over the right, as when displacing a gravid uterus through the incision, the rumen acts as a plug to hold the intestines in the abdomen. Although the rumen may partially prolapse through a left flank laparotomy, it is easier to manage one organ than countless loops of intestine which could be encountered during a right flank cesarean section.

Prior to incising, the incision site must be anesthetized. This can be performed via a line block, “inverted L” block, or a paravertebral nerve block. A paravertebral block is preferred in cattle, as it blocks all layers of the flank uniformly (barring the peritoneum) and allows for elongation of the incision if needed. Additionally, lidocaine within the incision makes the tissues edematous, and may slow healing. However, line block is often easier to accomplish in small ruminants. A limit of 5 mg/kg of lidocaine should be used in goats and sheep due to their increased susceptibility to lidocaine toxicity. If increased volume is needed, 2% lidocaine may be cut with saline to compound 1% lidocaine. Many larger ewes and does will stand throughout a cesarean section procedure, but this may not be the case for smaller breeds such as Nigerian dwarfs and pygmy goats. For these patients, right lateral recumbency is preferred. Most will remain recumbent with minimal restraint, but light sedation may be used. In some cases, anesthesia may be necessary, but runs higher risk for neonatal death.

Flank incisions are made at the caudal ⅓ of the paralumbar fossa. Following incision of the skin, the external abdominal oblique (EAO) muscle, internal abdominal oblique (IAO) muscle, transversus abdominus muscle, and peritoneum are all encountered as discreet layers. In the paralumbar fossa area, the fibers of the EAO run cranial to caudal, while the IAO run from caudodorsal to cranioventral. After left flank incision is performed, the uterus is identified. If the calf is in an anterior position, a pelvic limb foot and hock can be flexed to provide a handle. Steady traction moves the limb to the incision. Frequently the hock can be placed in the ventral aspect of the incision, providing self-retention. An incision is then made from hock to toes, both limbs are exteriorized through the hysterotomy, and the calf delivered.

If the calf is in a posterior presentation, and or a limb cannot be easily exposed, a foot can be pulled close to the incision. Following a small hysterotomy and exposure of the foot, a chain can be placed, and an assistant can apply traction, better exposing the uterus.¹

If the uterus cannot at all be exposed, and the contents of the uterus are relatively aseptic, the uterus may be opened intraabdominally. This can be accomplished with the aid of a sterilized letter opener.

During and following delivery of the calf, an effort should be made to maintain exteriorization of the uterus and minimize abdominal contamination of uterine contents. The fetal membranes should not be removed unless they easily separate, but a portion may be sharply cut away to facilitate uterine closure. The hysterotomy should be closed in an inverting pattern. An Utrecht or Cushing pattern should be used. Typically, a single layer closure is adequate.

If possible, an effort should be made to remove any abdominal blood clots and fibrin prior to closure of the laparotomy. There is little tension on flank incisions and thus large gauge (#2 or #3) chromic gut may be used for closure. Care should be taken to incorporate the external sheath of the EAO in the closure, as this is the holding layer of the flank muscles. Muscle layers may be closed separately or in varying combinations, but at least two layers should be closed beneath skin. When closing skin, a Ford interlocking pattern is used. The pattern should be completed a few centimeters dorsal to the ventral aspect, followed by 1–2 interrupted sutures ventrally. This allows opening of the incision in the case of a seroma/abscess without opening the entire skin closure.

Although calves have a variable survival rate (around ⅔ survival rate overall) depending on the length of dystocia, most dams perform well long-term following this procedure.¹ Less than half of the lambs and kids will survive cesarean section, again, with increased time in dystocia negatively impacting survival, and around 1 in 5 of the dams have been reported to die following the procedure.² Fertility in ruminants is minimally impacted by cesarean section.

Ventral Midline Cesarean Section

Ventral midline c-sections are reserved for ruminants in which the fetus is dead and emphysematous. This usually occurs when dystocia has gone on for 24 hours or more. In these cases, the fetus is bloated, and the uterus is desiccated of normal fluids and is contracted tightly to the fetus. These factors prevent vaginal delivery. Attempted fetotomy results in prolonged attempts in which only small pieces at a time are recovered, massive trauma to the uterus and often uterine rupture occurs. Therefore, cesarean section is the only viable option for removal of the fetus. Unfortunately, flank cesarean sections invariably are associated with minor spillage of uterine contents into the abdomen. In a healthy uterine environment, this is not a significant problem. However, when the fetus is emphysematous and decomposing, even a small amount of contamination can be catastrophic. A ventral midline approach is performed under general anesthesia or heavy sedation and allows full exposure of the uterus and removal of the fetus without contamination. An incision from cranial to the umbilicus to the udder is required. Closure of the body wall should be performed with strong, heavy gauge, multifilament suture in cattle and PDS in small ruminants.

As the uterus is contaminated and inflamed, there is a higher risk of infertility following the procedure. This combined with the higher cost of the procedure should be considered prior to undertaking this technique.

Ventrolateral Cesarean Section in Swine

Although cesarean section in swine is not practical in a true production setting, some veterinarians may find clients who own club pigs intended for exhibition in need of these services. If the gilt or sow in dystocia has been minimally palpated, the veterinarian should first attempt to resolve the dystocia vaginally. However, many owners attempt vaginal extraction for extended periods prior to calling a veterinarian and by this time, the vaginal canal is extremely swollen and traumatized. The underlying cause of dystocia is most commonly fetomaternal mismatch followed by uterine inertia. Pigs may present exhausted or even in shock, and swift action leads to improved outcomes.

The first step should be a lumbosacral or “high” epidural. This will anesthetize the flank and pelvic limbs for surgery. This site is just caudal to an imaginary line drawn between the cranial aspects of the tuber coxae, directly on midline. A 1-inch, 14-gauge needle can be used as a skin trocar and a 6-inch, 18-gauge spinal needle passed through the trocar and used to access the space. The hanging drop technique should be utilized. A dose of 1 ml of 2% lidocaine per 10 kg of body weight should be used, which is typically around 15–20 ml of 2% lidocaine per pig. The lidocaine should be administered slowly. Successful epidural administration is important for success, as it allows for less systemic sedation/anesthesia and increases the prognosis for the dam and piglets.

Following epidural administration, the dam should be heavily sedated or anesthetized. In a clinic setting, flow-by isoflurane works well. In the field, TKX (telozol-ketamine-xylazine) can be utilized, provided a reversal agent is prepared for administration to the piglets as they are delivered.

After induction, a catheter should be placed in an auricular vein for administration of fluids and additional electrolytes such as calcium. This is especially important in swine which present distressed or in shock.

The patient is positioned in lateral recumbency, and the uppermost pelvic limb abducted and tied caudally. An incision through the skin is made parallel to and just dorsal to the mammary chain, from the flank fold to 5 cm cranial to the inguinal region. The incision is extended through the rectus abdominus.

Once the abdomen is entered, the uterus is fully exteriorized. A hysterotomy is made in one of the horns close to the body, and piglets delivered through this incision. After closure with an inverting pattern, the abdominal wall is closed with 2 PDS, and skin with a pattern of the surgeon’s choosing.

Prognosis for survival of piglets and dam is good provided there is early intervention. Sows can farrow normally in subsequent pregnancies if owners attempt re-breeding.³

References

1.  Hiew MWH, Baird AN, Constable PD. Clinical signs and outcomes of beef cattle undergoing cesarean section because of dystocia. J Am Vet Med Assoc. 2018;252:864–872.

2.  Brounts SH, Hawkins JF, Baird AN, et al. Outcome and subsequent fertility of sheep and goats undergoing cesarean section because of dystocia: 110 cases (1981–2001). J Am Vet Med Assoc. 2004;224:275–279.

3.  Lozier JW, VanHoy GM, Jordan BA, et al. Complications and outcomes of swine that underwent cesarean section for resolution of dystocia: 110 cases (2013–2018). Vet Surg. 2021;50:38–43.