History

A 1-year-old primiparous female Boer cross goat was presented to the J. T. Vaughn Large Animal Teaching Hospital at Auburn University College of Veterinary Medicine with a history of prolonged first-stage labor following an otherwise uneventful pregnancy. When checking on the doe, the owner observed visceral organs protruding from the vulva and called the emergency service for assistance.

At the time of presentation, the doe was bright, alert, and responsive. Vital signs included a rectal temperature of 38.5 °C, heart rate of 126 beats per minute, and respiratory rate of 76 breaths per minute. Mucous membranes were pink and capillary refill time was < 3 seconds. Normal ruminations were auscultated at 1 rumination/2 min. The doe weighed 27.25 kg. Abdominal and thoracic viscera, including small intestines, liver, and heart, protruded from the vulva (Figure 1).

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A photograph of the hind end of a 1-year-old primiparous female Boer cross goat upon presentation to the emergency service. The tail is cut out of the top of the image with a portion of the anus in view. Abdominal and thoracic viscera, including small intestines, liver, and heart, protrude from the vulva.

Citation: Journal of the American Veterinary Medical Association 260, 9; 10.2460/javma.22.02.0067

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Question

What is the most likely diagnosis resulting in this dystocia?

Answer

Based on their size, the abdominal and thoracic organs protruding through the vulva were thought to be those of the fetus. Fetal organs can be located external to the fetal abdomen and thorax when congenital anomalies result in a failure of the abdominal and thoracic walls to fuse on the ventral midline. Schistosomus reflexus is a well-described congenital anomaly seen primarily in ruminant species and was the primary diagnostic rule-out based on the presentation of this case. Maternal abdominal organs could potentially exit the abdomen following a vaginal tear, but the thoracic organs would be retained by the diaphragm.

Results

Following examination and evaluation, Caesarian section was selected as the treatment to resolve the dystocia.

Acepromazine was administered at 0.2 mg/kg IM (0.5 mL). An epidural was given in the lumbosacral space using 3 mg/kg (total volume, 4 mL) of 2% lidocaine. The patient was positioned in right lateral recumbency, and the left paralumbar fossa was clipped and surgically prepped. The paralumbar fossa was stimulated to assess the degree of anesthesia provided by the epidural, and a line block using 2% lidocaine was administered to provide supplemental analgesia.

The abdomen was entered routinely through the caudal aspect of the paralumbar fossa. The uterus was located and the gravid horn elevated and exteriorized through the body wall incision. An incision was made through the uterine wall over the greater curvature of the uterine horn. The severely malformed kid with all abdominal organs and some thoracic organs located external to the fetal body wall was extracted from the uterus.

The uterine incision was closed routinely using No. 1 chromic gut in a Utrecht pattern, which was then oversewn with a second Utrecht pattern as a precaution. The uterus was inspected to rule out additional tears and was lavaged with sterile saline prior to being replaced in the abdomen. The abdominal musculature and peritoneum were closed routinely with No. 1 chromic gut. The skin was closed with No. 1 nylon.

Postoperatively, the doe received 1.1 mg/kg (0.6 mL) of flunixin meglumine (Banamine) IV every 24 hours and 2.2 mg/kg (1.2 mL) of ceftiofur sodium (Naxcel) SC every 24 hours. The doe was placed in a stall with ample hay and water and recovered from surgery uneventfully. The flunixin meglumine and ceftiofur sodium were continued for 4 treatments until the doe was discharged from the hospital.

The most remarkable finding of the fetus was a 7-cm-long ovoid defect in the ventral body wall, creating a thoracoabdominoschisis and exposing the pleural and peritoneal cavity with no fusion of the sternum and exteriorization of the heart. All organs were grossly unremarkable, aside from their location outside the body cavities. The lungs were atelectatic and within the pleural space. The vertebral column was U shaped with an almost 180° turn that brought the left forelimb into close apposition with the right hindlimb. All 4 limbs were arthrogrypotic and partially extended (Figure 2).

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Photograph of malformed kid extracted via caesarean section. Abdominal and thoracic organs are located outside the body cavity due to the thoracoabdominoschisis present. All 4 limbs are arthrogrypotic and partially extended.

Citation: Journal of the American Veterinary Medical Association 260, 9; 10.2460/javma.22.02.0067

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Discussion

Schistosomus reflexus is a rare fetal congenital disorder described most often in cattle and only occasionally observed in other ruminant species, horses, swine, dogs, or cats. This disorder is characterized by spinal inversion or retroflexion of the spinal column and failed closure of the ventral abdominal and/or thoracic wall, resulting in herniation of the abdominal viscera through a fissure of the ventral abdominal wall. Ankyloses of the limbs, causing abnormal positioning of the limbs adjacent to the skull, often results in dystocia. Reported components of schistosomus reflexus include scoliosis, cleft sternum, exposure of thoracic viscera, and abnormalities of the digestive and urogenital system. The prevalence of a schistosomus reflexus was reported to be 1.3% of all bovine dystocias in 1996.¹ The prevalence of schistosomus reflexus is not reported in sheep and goats, but in sheep, dystocia due to congenital defects of the fetus occurred in 2% of births, with arthrogryposis accounting for half of those congenital defects.²

Although many other congenital anomalies such as chondrodysplasia, brachyspina, and congenital vertebral malformation are known to be caused by inherited mutations, no specific mutation has been linked to schistosomus reflexus in cattle. Schistosomus reflexus abnormalities cause defects in the abdominal wall, implying that abnormal development of the schistosomus reflexus fetus is initiated as early as the postgastrulation stages of embryonic development.³ There are similar conditions in cattle involving defects of the ventral abdomen, including omphaloceles, but the pathogenesis is still unknown at this time.

An inherited basis for bovine schistosomus reflexus is supported by some reports in cattle of clusters of this deformity from offspring of the same bull, or offspring with that particular bull in their pedigree. A similar syndrome in humans called thoracoabdominal syndrome has been localized to a specific gene.⁴ In a 1999 report⁵ of 2 cases of schistosomus reflexus in the same goat herd, an inbreeding coefficient of 25% suggested that this might be a heritable defect. These reports have led to the recommendation that after the occurrence of a schistosomus reflexus fetus in any species, that specific breeding cross should not be performed again and a sire from a different lineage should be chosen.

Teratogenic plants are a common cause of fetal anomalies in ruminants. The type of fetal abnormality is dependent on the specific toxin, amount of toxin exposure, and time of exposure during fetal development. Teratogenic plants include locoweed, lupines, poison hemlock (Conium maculatum), false hellebore (Veratrum californicum), and many others. Despite many well-documented cases of teratogenic plant exposures in ruminants, no causal link has been established for schistosomus reflexus.

Management of dystocia due to a schistosomus reflexus may sometimes be accomplished with manual traction and vaginal extraction of the fetus, but more commonly requires fetotomy or a C-section for removal. There are several reports of caprine schistosomus reflexus fetuses being removed via manual traction through the vagina. Similarly, in cattle, the fetus can occasionally be delivered intact, but fetotomy is a commonly suggested management strategy. Depending on the degree of scoliosis and ankyloses and the condition and temperament of the patient, a C-section may be preferred.

Outcome

The doe was maintained in the hospital overnight following surgery and discharged to the home farm for postoperative care. No postoperative complications were reported by the owner. Four months after surgery, the doe was presented for a lameness exam, and the surgical site had healed well. At that time, there were no immediate plans to breed the doe again. The owner was advised that the specific cross resulting in the schistosomus reflexus fetus should not be performed again and that a sire from a different genetic line should be used.