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Tracey D. Jensen Wellington Veterinary Clinic, 3706 Cleveland Ave, Wellington, CO 80549.

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James C. Hathaway Wellington Veterinary Clinic, 3706 Cleveland Ave, Wellington, CO 80549.

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History

A 3-year-old 27-kg (60-lb) female mixed-breed dog was evaluated for dystocia of 8 hours' duration. Two years earlier, the dog had whelped a litter of 6 puppies without difficulties. The dog was in stage III labor with active, relentless uterine contractions, and a 12-cm spherical, firm, nonreducible mass was protruding from the vulva. No puppies had been delivered, and except for the mass, no discharge had been detected from the vulva. Abnormalities detected on CBC and serum biochemical analyses included mild, nonregenerative anemia (PCV, 34.4%; reference range, 37% to 55%) and mild hypoalbuminemia (albumin, 2.3 mg/dL; reference range, 2.3 to 3.7 mg/dL), respectively. A radiograph of the caudal portion of the abdomen was obtained (Figure 1).

Figure 1—
Figure 1—

Lateral radiographic view of the caudal portion of the abdomen of a 3-year-old female mixed-breed dog evaluated for dystocia of 8 hours' duration.

Citation: Journal of the American Veterinary Medical Association 229, 5; 10.2460/javma.229.5.673

Determine whether additional imaging studies are required, or make your diagnosis from Figure 1—then turn the page

Radiographic Findings and Interpretation

Seven term fetuses were evident within the abdomen. An additional fetus, which did not appear to be in the abdomen, was located caudal to the abdominal wall at the level of the left femur (Figure 2). The nonreducible mass protruding from the vulva appeared as a soft tissue opacity caudal to the tuber ischii. The mass did not contain a fetus as evidenced by lack of mineralization or gas pattern. On the basis of the physical examination and radiographic findings, differential diagnoses for the cause of dystocia included vaginal prolapse and vaginal obstruction attributable to a fetus herniated through the left inguinal canal. Differential diagnoses for the vulvar mass included vaginal prolapse (vaginal hyperplasia, vaginal hypertrophy, estrual hypertrophy, vaginal eversion, or vaginal protrusion), vaginal neoplasia (benign polyp, leiomyoma, and transmissible venereal tumor), urethral neoplasia, uterine prolapse, and vaginal polyps.1,2

Figure 2—
Figure 2—

Same radiographic view as in Figure 1. Notice an extra-abdominal fetus parallel to the left femur (large arrow). The remaining 7 fetuses are intra-abdominal.

Citation: Journal of the American Veterinary Medical Association 229, 5; 10.2460/javma.229.5.673

Comments

Orthogonal radiographic views are preferred for appropriate radiographic analysis; however, the dog had signs of distress and became aggressive when attempts were made to obtain a ventrodorsal radiographic view. Palpation confirmed the location of the eighth fetus to be extra-abdominal in the left inguinal region.

The radiographic findings were consistent with a term pregnancy; the cause of dystocia was thought to be the extra-abdominal fetus.3 Exploratory abdominal surgery revealed deviation of the left uterine horn through the left inguinal canal causing deviation of the uterine body and cervix also to the left of midline. The result was mechanical dystocia; neither the left nor right uterine horn was able to expel a fetus. The extraabdominal fetus was found to be the most caudal fetus in the left uterine horn. Because of the small size of the inguinal canal, it appeared that the fetus had passed through the inguinal canal early in gestation, developing extra-abdominally during approximately the last 30 days of gestation. Seven viable puppies were recovered via cesarean section.4 An incision was made directly over the extra-abdominal fetus, which was fully developed but not viable. Following ovariohysterectomy, the inguinal defect was repaired and the prolapsed bladder was returned to the abdominal cavity. The dog recovered from anesthesia without complications.

The definition of dystocia is difficult birth or the inability to expel a conceptus from the uterus through the birth canal.5 Dystocia may be caused by maternal or fetal abnormalities. Inguinal hernias entrapping a fetus or entire uterine horns are an unusual cause of dystocia, but they have been reported.5 Maternal factors contributing to dystocia include uterine inertia, small pelvic size, or abnormality in vaginal size or structure. Fetal abnormalities contributing to dystocia include fetal death, ectopic positioning, and large fetal size.

Abdominal imaging is extremely important in determining the cause of dystocia. Radiography, ultrasonography, or both may be used. Radiography is useful in determining the number of fetuses, or assessing fetal abnormalities such as fetal death, large fetal size, or malpositioning. Because mineralization results in radiographically identifiable structures such as vertebrae, ribs, and limbs, it may also be used to crudely assess stage of fetal development.3 Maternal factors, such as pelvic size, can be compared with fetal size, and the presence of a fetus within the pelvic canal can be determined.

Treatment of dystocia may be medical or surgical, depending on the underlying cause. Because of the extra-abdominal location of 1 fetus in the dog of this report, dystocia was caused by mechanical obstruction.

  • 1

    Manothiaudom K, Johnston SD. Clinical approach to vaginal/vestibular masses in the bitch. Vet Clin North Am Small Anim Pract 1991;21:509521.

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  • 2

    Memon MA, Pavletic MM, Kumar MS. Chronic vaginal prolapse during pregnancy in a bitch. J Am Vet Med Assoc 1993;202:295297.

  • 3

    Feeney DA, Johnston GR. The uterus. In:Thrall DE, ed.Textbook of veterinary diagnostic radiology. 3rd ed.Philadelphia: WB Saunders Co, 1998;494499.

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  • 4

    Gilson SD. Cesarean section. In:Textbook of small animal surgery. 3rd ed.Philadelphia: WB Saunders Co, 2003;15171520.

  • 5

    Nelson RW, Feldman EC. Periparturient diseases. In:Canine and feline endocrinology and reproduction. 3rd ed.Philadelphia: WB Saunders Co, 2004;816817.

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