History
A 10-year-old multiparous Quarter Horse mare with a body weight of 500 kg (1,100 lb) was admitted to the Murray Veterinary Services equine hospital for investigation of abnormal findings discovered during a routine prebreeding reproductive examination performed at a breeding farm in November during the Southern Hemisphere breeding season. A single dose of cloprostenola (250 μg, IM) was administered 4 days prior to the prebreeding reproductive examination, and the mare was displaying signs consistent with estrus at the time of the examination. The breeding farm manager reported that during the previous breeding season, the mare had been confirmed pregnant at day 28 of gestation; the mare was then transported to the owner's farm. Subsequently, the mare did not foal. The owner of the mare did not notice signs consistent with abortion, and it was presumed that the fetus was resorbed.
The mare was admitted to our equine hospital, and a complete physical examination was performed. Physical examination revealed the mare to be in good condition (body condition score, 5/9). All vital parameters were within reference limits, and there was no evidence of discharge from the vulva.
The mare was restrained in stocks, and a reproductive examination was performed that included transrectal palpation and ultrasonographyb and a vaginoscopic examination. Transrectal palpation revealed a nongravid uterus and relaxed cervix. The left and right uterine horns were palpably asymmetrical, with the left uterine horn being larger. Palpation revealed no evidence of crepitus. Both ovaries were detected, and ovulation fossae were palpable.
Transrectal ultrasonography revealed that the dominant ovarian structure was a 35-mm follicle on the left ovary. There was a moderate amount of uterine edema. Additionally, luminal fluid (depth of approx 4 cm) was detected. The fluid was of mixed echogenicity and located in an area where hyperechoic linear structures were visible at the base of the left uterine horn (Figure 1).
Transrectal ultrasonographic image of the uterus of a mare containing mixed hyperechogenic luminal fluid and hyperechoic linear structures at the base of the left uterine horn. Tick marks on the right side are at intervals of 1 cm.
Citation: Journal of the American Veterinary Medical Association 254, 2; 10.2460/javma.254.2.209
The perineum was aseptically prepared. A vaginoscopic examination was performed, which revealed a relaxed cervix with no evidence of cervical trauma or discharge. Findings of the examination were consistent with a mare in estrus with a notable intrauterine abnormality.
Question
What additional diagnostic procedure could be used to aid in the diagnosis of the intrauterine abnormality? Please turn the page.
Answer
Hysteroscopy.
Results
The mare was sedated by the administration of detomidine hydrochloride (0.01 mg/kg [0.0045 mg/lb], IV) and butorphanol tartrate (0.01 mg/kg, IV). The perineum was aseptically prepared, and a sterile gloved hand of the clinician was used to guide the distal end of a 1-m videoendoscopec into the vagina. The videoendoscope then was passed through the cervix into the uterus. The cervix was held tightly closed around the videoendoscope to form a seal that facilitated insufflation of the uterus with air. The videoendoscope was advanced toward the base of the left uterine horn and positioned immediately caudal to the hyperechoic linear structures identified during transrectal ultrasonography. Remnants of a fetal skeleton were visible (Figure 2).
Videoendoscopic photograph of a partial fetal skeleton at the base of the left uterine horn of the mare of Figure 1.
Citation: Journal of the American Veterinary Medical Association 254, 2; 10.2460/javma.254.2.209
After the skeletal remnants were identified, an endoscopic snared was passed through the biopsy channel of the videoendoscope. The snare was used to reposition the larger fragments of the fetal skeleton at the internal cervical os, which allowed simple manual removal once the videoscope was removed. Bones removed included skull fragments, 18 pairs of ribs, a scapula, the sacrum, and an ilium. Some small unidentified bones were removed simultaneously with the larger bones. Uterine lavage was performed with 3 L of isotonic fluid,e which resulted in the removal of several other small fetal bones. After the lavage was completed, the mare was administered oxytocin (20 U, IV) and flunixin meglumine (1.1 mg/kg [0.5 mg/lb], IV), and treatment with trimethoprim-sulfamethoxazole (30 mg/kg [13.6 mg/lb], PO, q 12 h) was initiated.
The following day, the mare was placed in the stocks and aseptically prepared as previously described. Repeated hysteroscopy was used to ensure that all fetal bones had been successfully removed. The videoendoscope allowed for visual examination of the entire uterus; there was no evidence of any remaining fetal remnants (Figure 3). After the videoendoscopic examination was completed, the uterus was massaged per rectum to aid in the expulsion of air.
Videoendoscopic photograph of the uterus of the mare of Figure 1 that is devoid of fetal bones following hysteroscopically assisted retrieval and uterine lavage.
Citation: Journal of the American Veterinary Medical Association 254, 2; 10.2460/javma.254.2.209
Discussion
Fetal maceration is a rare condition in horses that most often occurs in midgestation when a mare fails to expel a dead fetus.1 The process of fetal autolysis, which is amplified by bacterial contamination, results in fetal degradation. The presence of a partially mineralized fetal skeleton at this stage of gestation impairs complete uterine resorption of the fetal tissues.2 Uterine inertia, fetal malpositioning, and cervical incompetence have been implicated as causes of fetal retention.3,4 Descriptions of fetal maceration in mares are scarce; however, all of the reports indicate the mares had been bred the year prior to the fetal maceration. Of the published cases, 4 of 5 mares were initially evaluated because of purulent or hemorrhagic discharge from the vulva.1,3,5,f In addition, at the time when they were examined, 2 mares were known to have aborted,1,3 and 1 mare had fetal membranes protruding through a stenotic cervix.4 In the mare described in 1 report,1 hemorrhagic discharge from the vulva was apparent only after the mare had been bred by a stallion. It could be surmised that the physical act of breeding caused the fetal bones to become embedded in the endometrium, which initiated the hemorrhage.1
The mare of the present report had been bred during the previous breeding season. The mare became pregnant but did not give birth to a live foal. Furthermore, the owner did not notice evidence of abortion.
For the present breeding season, there was no mention of cervical incompetence or malformation prior to breeding of the mare, nor did the medical record include evidence of discharge from the vulva. The linear hyperechogenic ultrasonographic images in conjunction with the breeding history led to the presumptive diagnosis of a retained fetus or fetal remnants by the attending on-farm veterinarian. Hysteroscopy was used to confirm the diagnosis and assess the endometrial surface before proceeding with treatment.
Treatment for a mare with a macerated fetus is directed at removal of the fetal remnants, which is followed by treatment of any uterine infection. Authors of case reports have described conservative approaches that include manual removal of fetal bones through a dilated cervix,1–3,f repeated uterine lavage with isotonic solutions,1,2,f or uterine lavage with concurrent intrauterine administration of effervescent antimicrobials.3,f Topical application of prostaglandin E1 has been used to medically enhance cervical relaxation and dilation to facilitate the subsequent manual removal of macerated twin fetuses.5 Surgical resolution via hysterectomy in a Miniature Horse has also been reported.4
On the basis of techniques described in another report6 on the use of hysteroscopic guidance for the retrieval of single foreign bodies from the uterus of mares, we elected to incorporate the use of the videoendoscope with an endoscopic snare to aid in the removal of the fetal skeleton. This decision was based on 2 reasons. First, use of the videoendoscope and snare allowed us to ensure that the fetal bones were freely moveable and not embedded in the endometrium. Second, despite the fact the cervix was relaxed at the time of examination because the mare was in estrus, we did not believe that additional time, IM administration of prostaglandin F2α, or topical application of prostaglandin E1 or any other relaxant to the cervix would result in dilation that would allow the passage of a clinician's gloved hand into the uterine lumen.
Use of the videoendoscope and snare allowed the authors to retrieve most of the larger bones, and additional smaller bones were removed during uterine lavage. Because the entire fetal skeleton was not present, it is possible that the mare may have expelled some bones before the examination and hysteroscopy. For this mare, administration of trimethoprim-sulfamethoxazole was initiated empirically and continued for 5 days; it was selected on the basis of its broad-spectrum antimicrobial activity.
The case described here highlighted the use of hysteroscopy. Hysteroscopy provided a definitive diagnosis for the uterine abnormality, and it also was used for timely transcervical retrieval of the fetal bones, which negated the need to wait for additional natural cervical relaxation or medically induced cervical dilation. The case described here should serve as an example of the importance of performing a prebreeding examination for any mare with a history of fetal loss, especially when a history of a known abortion is lacking. Fetal maceration and the subsequent retention of fetal bones are rare. However, if left untreated, the presence of a uterine foreign body may lead to chronic endometritis and subsequent endometrial fibrosis that could severely impact the future reproductive performance of an affected mare.
Outcome
The mare was discharged 3 days after admission. Discharge instructions included sexual rest for the remainder of the breeding season. Antimicrobial treatment was continued for a total of 5 days. The authors recommended that bacterial culture and cytologic examination of a uterine swab sample be performed prior to another breeding of the mare.
The mare returned to the breeding farm the following breeding season. While the mare was in estrus, a prebreeding reproductive examination was performed; the examination included transrectal palpation and ultrasonography and culture and cytologic examination of a uterine swab specimen. There was no evidence of microbial growth, and results of uterine cytologic examination were within anticipated limits. The mare was bred by a stallion, and transrectal palpation and ultrasonography performed 16 days after mating revealed a single embryonic vesicle at the base of the left uterine horn. The mare was discharged to the owner with the recommendation that she be examined again at days 30, 45, 60, and 120 of gestation to ensure that the pregnancy was developing normally and that the fetus was viable. The mare gave birth to a live healthy foal.
Acknowledgments
No funding support was provided for this report. The authors declare that there were no conflicts of interest.
Footnotes
Juramate, 250 μg/mL, Jurox Animal Health, Rutherford, NSW, Australia.
M-Turbo ultrasound, Sonosite Inc, Bothell, Wash.
Pentax EG-2931K gastroscope, Pentax Medical, Montvale, NJ.
Snaremaster electrosurgical snare, Olympus American Inc, Miami, Fla.
Viaflex Hartmann solution, Baxter Healthcare Corp, Deerfield, Ill.
Nóbrega FS, Beck CA, Ferreira MP. Fetal maceration in pony (abstr). Acta Sci Vet 2011;39:1007.
References
1. Burns TE, Card CE. Fetal maceration and retention of fetal bones in a mare. J Am Vet Med Assoc 2000;217:878–880.
2. Card CE. Fetal maceration and mummification. In: McKinnon AO, Squires EL, Vaala WE, et al, eds. Equine reproduction. Vol 2. 2nd ed. West Sussex, England: Wiley Blackwell, 2011;2373–2375.
3. Vézina J, Marcoux M, Phaneuf JB. Fetal maceration in a mare [in French]. Can Vet J 1975;16:20–21.
4. Santschi EM, Adams SB, Robertson JT, et al. Ovariohysterectomy in six mares. Vet Surg 1995;24:165–171.
5. Frazer GS. Recent advances in equine obstetrics, in Proceedings. Annu Conf Soc Theriogenol 2004;61–92.
6. Card CE, Eaton S, Ghamesi F. How to perform hysteroscopically assisted endometrial biopsy and foreign body retrieval in mares, in Proceedings. Annu Conf Am Assoc Equine Pract 2010;56:328–330.
