Editorial Type: Case Reports
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Online Publication Date: 01 Nov 2014

Regression of a Vaginal Leiomyoma After Ovariohysterectomy in a Dog: A Case Report

BVSc, MVSc and
MS, DVM, DACVS
Article Category: Case Report
Page Range: 424 – 428
DOI: 10.5326/JAAHA-MS-6082
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An 11 yr old female mixed-breed Siberian husky was presented with a history of sanguineous vaginal discharge, swelling of the perineal area, decreased appetite, and lethargy. A single, large vaginal leiomyoma and multiple mammary tumors were diagnosed. Mastectomy and ovariohysterectomy were performed. The vaginal leiomyoma regressed completely after ovariohysterectomy. This is the first reported case of spontaneous regression of a vaginal leiomyoma after ovariohysterectomy in a dog.

Introduction

Vaginal and vulvar tumors account for 2.4–3% of all canine tumors.1–3 The majority of tumors at this site are benign.3 In one study, 78% of those tumors were leiomyomas.1 Leiomyomas are slow growing, noninvasive, nonmetastatic, smooth muscle masses that rarely cause clinical signs.4 When seen, clinical signs may include perineal swelling, dysuria, tenesmus, pollakiuria, tissue prolapse through the vestibule, and pain during breeding.5 The age group of affected dogs is between 5 and 16 yr, with average age of 10.8 yr.1 The cause of reproductive tumors is not known; however, the influence of ovarian hormones is strongly suspected. Surgical excision has been the recommended modality along with ovariohysterectomy for treating and preventing the recurrence of leiomyomas. Surgery may include either episiotomy and mass excision or more aggressive procedures such as vaginectomy, urethroplasty, and ventral pelvic osteotomy.6,7 However, it has been reported that vaginal tumors may regress with ovariohysterectomy.8 To the authors’ knowledge, this is the first case report of a vaginal leiomyoma that regressed following ovariohysterectomy in a dog.

Case Report

An 11 yr old female mixed-breed Siberian husky was presented to the veterinary teaching hospital at the Western College of Veterinary Medicine, with a 3 wk history of sanguineous vaginal discharge, swelling of the perineal area, decreased appetite, and lethargy. On physical examination, the dog was quiet but alert and responsive. Her body condition score was 3/5. The body temperature was 38.4°C, heart rate was 88 beats/min, and respiratory rate was 36 breaths/min. Mucous membranes were pink and the capillary refill time was 1 sec. A serosanguineous, nonmalodorous vaginal discharge was present. Thoracic auscultation and abdominal palpation were unremarkable. The perineal area appeared distorted due to a swelling between the anus and vulva (Figure 1). Vaginal examination revealed a smooth, nonpainful mass measuring 8 cm × 7 cm × 6 cm involving the left lateral vaginal wall and vestibule. The vaginal discharge was coming from a few small, eroded areas on the mass. The caudal extent of the mass could not be fully appreciated on palpation. There were also firm, nonpainful masses in the left fourth and fifth and right fourth and fifth mammary glands.

FIGURE 1. Photograph of the perineal area showing the distortion caused by the vaginal mass.FIGURE 1. Photograph of the perineal area showing the distortion caused by the vaginal mass.FIGURE 1. Photograph of the perineal area showing the distortion caused by the vaginal mass.
FIGURE 1 Photograph of the perineal area showing the distortion caused by the vaginal mass.

Citation: Journal of the American Animal Hospital Association 50, 6; 10.5326/JAAHA-MS-6082

Initial diagnostic tests included complete blood cell count, serum biochemical analysis, urinalysis, prothrombin time, partial thromboplastin time, thoracic radiographs, abdominal radiographs, abdominal ultrasound, and ultrasound of the vaginal mass.

The complete blood cell count revealed a moderate leukocytosis (23.6 × 109/L; reference range, 4.8–13.9) and mild neutrophilia (22.64 × 109/L; reference range, 3–10) with a mild left shift (0.236 × 109/L; reference range, 0.0–0.1). There was lymphopenia (0.472 × 109/L; reference range, 1.2–5) consistent with a stress leukogram. Serum biochemical analysis revealed mild increases in cholesterol (9.82 mmol/L; reference range, 2.7–5.94), total bilirubin (5 mmol/L; reference range, 1–4), and alkaline phosphatase (109 mmol/L; reference range, 9–90). The mild increase in bilirubin and alkaline phosphatase suggested cholestasis. The potassium (3.6 mmol/L; reference range, 3.8–5.6) and urea (3.1 mmol/L; reference range, 3.5–11.4) were mildly decreased, likely due to inappetence. The urinalysis revealed hematuria with 4+ blood on the strip reagent and 60–80 red blood cells/high-power field. The hematuria was likely from contamination from the sanguineous vaginal discharge because the urine was a voiding sample. The prothrombin time was mildly decreased at 6.9 sec (reference range, 7.5–9.9) and the partial thromboplastin time was normal at 13 sec (reference range, 9.6–13.8).

Thoracic and abdominal radiographs and abdominal ultrasound were normal. Ultrasonography of the vaginal mass revealed a moderately vascular structure with 3–4 small, echolucent, centrally located structures suggestive of necrosis (Figure 2).

FIGURE 2. Ultrasound image of the vaginal mass.FIGURE 2. Ultrasound image of the vaginal mass.FIGURE 2. Ultrasound image of the vaginal mass.
FIGURE 2 Ultrasound image of the vaginal mass.

Citation: Journal of the American Animal Hospital Association 50, 6; 10.5326/JAAHA-MS-6082

The dog was anesthetized, and vaginoscopy and cystoscopy were attempted; however, visualization of the urethral papilla was not possible due to the presence of the mass. Samples of the mass were collected for histopathological evaluation, which revealed spindle cells and well-differentiated smooth muscle cells with necrosis and suppurative inflammation. Immunohistochemistry was positive for smooth muscle actin. Based on those findings, the mass was diagnosed as a leiomyoma.

A computed tomography of the caudal abdomen and the perineum was done to further evaluate the size and location of the mass and to localize the urethra relative to the mass. A round, noninvasive mass measuring 8 cm × 7 cm × 6 cm involving the ventral vaginal wall was evident (Figures 3, 4, 5). There were 6–7 small areas of increased lucency suggestive of necrosis. The relationship of the urethra to the mass could not be ascertained, and attempts to catheterize the urethra were unsuccessful because of the size and the location of the mass.

FIGURE 3. A: Computed tomography (CT) of the perineum showing the cranial aspect of the vaginal mass (axial view). B: The corresponding localizer image. L, left; R, right.FIGURE 3. A: Computed tomography (CT) of the perineum showing the cranial aspect of the vaginal mass (axial view). B: The corresponding localizer image. L, left; R, right.FIGURE 3. A: Computed tomography (CT) of the perineum showing the cranial aspect of the vaginal mass (axial view). B: The corresponding localizer image. L, left; R, right.
FIGURE 3 A: Computed tomography (CT) of the perineum showing the cranial aspect of the vaginal mass (axial view). B: The corresponding localizer image. L, left; R, right.

Citation: Journal of the American Animal Hospital Association 50, 6; 10.5326/JAAHA-MS-6082

FIGURE 4. A: CT of the perineum showing the midportion of the vaginal mass (axial view). B: The corresponding localizer image. L, left; R, right.FIGURE 4. A: CT of the perineum showing the midportion of the vaginal mass (axial view). B: The corresponding localizer image. L, left; R, right.FIGURE 4. A: CT of the perineum showing the midportion of the vaginal mass (axial view). B: The corresponding localizer image. L, left; R, right.
FIGURE 4 A: CT of the perineum showing the midportion of the vaginal mass (axial view). B: The corresponding localizer image. L, left; R, right.

Citation: Journal of the American Animal Hospital Association 50, 6; 10.5326/JAAHA-MS-6082

FIGURE 5. A: CT of the perineum showing the caudal aspect of the vaginal mass (axial view). B: The corresponding localizer image. L, left; R, right.FIGURE 5. A: CT of the perineum showing the caudal aspect of the vaginal mass (axial view). B: The corresponding localizer image. L, left; R, right.FIGURE 5. A: CT of the perineum showing the caudal aspect of the vaginal mass (axial view). B: The corresponding localizer image. L, left; R, right.
FIGURE 5 A: CT of the perineum showing the caudal aspect of the vaginal mass (axial view). B: The corresponding localizer image. L, left; R, right.

Citation: Journal of the American Animal Hospital Association 50, 6; 10.5326/JAAHA-MS-6082

Surgical removal of the vaginal mass, removal of the mammary masses, and ovariohysterectomy were recommended. Because the vaginal mass was not causing any clinical signs and would have required fairly extensive vaginectomy and vestibulectomy, the procedures were staged. Ovariohysterectomy, lumpectomy at the left fourth mammary gland and mastectomy of the left fifth and right fourth and fifth mammary glands were performed with the vaginal mass excision to follow at a later date.

The patient was reexamined 2 wk after surgery. The vaginal mass appeared grossly smaller than before, measuring 6.2 cm × 5.2 cm. The vaginal discharge was also reduced. It was decided to monitor the mass for further change in size, and surgery was delayed. Reevaluation 4 and 8 wk after surgery revealed further diminution of the mass. Twelve weeks after ovariohysterectomy, the mass was no longer palpable.

Discussion

Leiomyomas are slowly growing, noninvasive, benign, smooth muscle tumors that result in clinical signs when they reach an appreciably large size.9 Reported clinical signs of leiomyomas include swelling of the perineum, dysuria, tenesmus, pollakiuria, prolapsed tissue through the vulva, and unwillingness to allow copulation.5 The clinical sign that prompted the owners to seek veterinary attention for this dog was primarily the sanguineous vaginal discharge and also the perineal swelling. Although vaginal discharge is not a common clinical sign reported with vaginal masses, the large size of the vaginal mass might have caused it to develop some areas of necrosis resulting in the sanguineous vaginal discharge.

The age of the dog in this report was consistent with previous reports, stating the average age to be 10.8 yr.1,3,10 This dog was also an intact female, which is consistent with previous reports except one in which a uterine leiomyoma was diagnosed in a spayed female poodle.11 However, residual ovarian tissue was found on exploratory laparotomy in that report.

The cause of canine reproductive tumors is unknown, but ovarian hormones are thought to play a strong role.12 Leiomyomas have been reported in association with chronic estrogen stimulation as a result of hormone production either by ovarian follicular cysts or estrogen secreting ovarian tumors.13 Many of those animals also have endometrial hyperplasia and mammary gland tumors, which are known to result from hormonal influence.14 Although the dog described in this report did have mammary tumors, no gross evidence of ovarian tumor was found. However, the absence of hormone-producing ovarian follicular cysts cannot be ruled out because the ovaries were neither closely inspected nor histologically analyzed. The absence of any reports of leiomyomas in spayed dogs suggests that hormones have a role in their occurrence.

In women, although the cause(s) of uterine leiomyoma or fibroids are unknown, the scientific literature now contains a sizeable body of information pertaining to the epidemiology, genetics, hormonal aspects, and molecular biology of these tumors.15 The role of estrogen, progesterone, and growth factors in promoting the development of the tumor has been widely studied and reported. One hypothesis suggests that increased levels of estrogen and progesterone result in an increased mitotic rate that may contribute to myoma formation by increasing the likelihood of somatic mutation.16 The increased incidence of uterine leiomyoma in women receiving hormone replacement therapy also suggests that ovarian hormones have a strong role in tumor occurrence and growth.17

The treatment recommended for vaginal leiomyoma is surgical excision with ovariohysterectomy to prevent recurrence.6,13 Vaginal leiomyomas may be sessile or pedunculated. Pedunculated masses are relatively easy to remove compared with sessile masses. Often, surgical excision requires episiotomy for adequate exposure. Some tumors, depending on size, site of attachment and association to other structures (i.e., urethra), may require more aggressive procedures, such as vulvovaginectomy, urethroplasty, and perineal urethrostomy.7,18,19 Although good success has been reported with surgical excision, potential complications include damage to the urethra or other perineal structures, infection, dehiscence, and scar formation causing urethral obstruction.6

Although ovariectomy/ovariohysterectomy has not been commonly recommended as the sole treatment of vaginal leiomyoma, it has been stated that most vaginal tumors are hormone responsive and regress after ovariohysterectomy.8 In the dog described in this report, ovariohysterectomy led to complete regression of a very large vaginal mass and thus eliminated the risk factors and morbidity associated with surgical excision.

Conclusion

This case appears to be the first published report of spontaneous regression of a leiomyoma after ovariohysterectomy in a dog. In selected dogs, either ovariohysterectomy or ovariectomy as a stand-alone treatment could be considered to treat vaginal leiomyomas.

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Copyright: © 2014 by American Animal Hospital Association 2014
FIGURE 1
FIGURE 1

Photograph of the perineal area showing the distortion caused by the vaginal mass.

FIGURE 2
FIGURE 2

Ultrasound image of the vaginal mass.

FIGURE 3
FIGURE 3

A: Computed tomography (CT) of the perineum showing the cranial aspect of the vaginal mass (axial view). B: The corresponding localizer image. L, left; R, right.

FIGURE 4
FIGURE 4

A: CT of the perineum showing the midportion of the vaginal mass (axial view). B: The corresponding localizer image. L, left; R, right.

FIGURE 5
FIGURE 5

A: CT of the perineum showing the caudal aspect of the vaginal mass (axial view). B: The corresponding localizer image. L, left; R, right.

Contributor Notes

Correspondence: sureshwcvm@gmail.com (S.S.)
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