+ General Considerations

  • Vaginal and vulval tumors are the 2nd most common canine reproductive tumor and account for 2.4%-3.0% of all canine tumors
  • Majority of vaginal and vulval tumors are benign:
  • Leiomyoma and fibroma in cat
  • Leiomyoma and lipoma in dog

+ Leiomyoma

  • 86% of vaginal and vulvar tumors are benign smooth muscle tumors (i.e., leiomyoma and fibroma)
  • Majority of leiomyomas arise from vestibule of vulva rather than vagina
  • Extraluminal and intraluminal forms have been described:
  • Extraluminal present with a slow-growing perineal mass
  • Intraluminal are attached to vestibular or vaginal wall by variably sized pedicle and can be multiple
  • Mucosa is generally intact but ulceration may occur with exposure and irritation
  • Leiomyoma may be hormone dependent:
  • Leiomyoma has not been diagnosed in dogs ovariectomized < 2 years
  • 15% local tumor recurrence rate in intact and 0% in dogs following ovariohysterectomy
  • Mean age 10.8 years
  • Breed predisposition: Boxer
  • Incidence of leiomyoma higher in nulliparous bitches
  • 33% associated with cystic endometrial hyperplasia, ovarian cysts, and mammary gland tumors

+ Lipoma

  • Lipoma can arise from perivascular or perivaginal adipose tissue and attach to tuber ischii
  • Lipoma can lie within pelvic canal and are usually well-circumscribed and relatively avascular
  • Mean age 6.3 years

+ Transmissible Venereal Tumor

  • Transmissible venereal tumors occurs in 4-5-year-old dogs with increased risk in free roaming dogs
  • Cell origin of transmissible venereal tumors is unknown, but an undifferentiated round cell tumor of reticuloendothelial origin is most likely
  • Transmissible venereal tumors have a common origin as chromosomal aberrations are constant and highly specific
  • Virus particles have been identified in transmissible venereal tumors
  • However, viral etiology is unlikely as the disease cannot be transmitted by cell-free filtrates
  • Transmissible venereal tumors are transmitted by contact with genital mucous membranes during coitus
  • Transmissible venereal tumors appear as multiple tumors along the mucosal lining of the vagina and vestibule

+ Other

  • Benign tumors: sebaceous adenoma, fibrous histiocytoma, benign melanoma, myxoma, and myxofibroma
  • Malignant tumors: leiomyosarcoma, ADC, SCC, TCC, HSA, OSA, MCT, and epidermoid carcinoma
  • Carcinoma of bladder or urethra may present with palpably enlarged urethral papilla


+ Clinical Signs

  • Duration of clinical signs longer for extraluminal compared to intraluminal leiomyoma
  • Intraluminal leiomyoma often presents as mass extruding between vulval lips, particularly during estrous
  • Other clinical signs include vulval bleeding or discharge, enlarging vulvar mass, dysuria, hematuria, tenesmus, excessive vulval licking, and dystocia
  • Lipomas usually present with a slowly growing mass impinging on adjacent structures

+ Diagnosis

  • Vaginoscopic examination, retrograde vaginography, and urethrocystography may delineate mass
  • Ultrasonography, FNA, and histopathology


+ Medical Management

  • Local tumor recurrence rate is high for dogs with transmissible venereal tumor and surgery is not recommended
  • Transmissible venereal tumors are very response to chemotherapy and radiation therapy
  • Chemotherapy: vincristine 0.5-0.7 mg/m 2 IV 4-8 times ± doxorubicin

+ Surgical Management – Benign Tumors

  • Exploratory celiotomy for ovariohysterectomy (due to hormonal dependence and local tumor recurrence)
  • Conservative surgical resection
  • Wide resection probably not required if ovariohysterectomy performed concurrently
  • Dorsal episiotomy may be required to provide adequate visualization and ensure complete resection
  • Dorsal episiotomy indicated for extraluminal vaginal and vulvar tumors as tumors are usually well-circumscribed and poorly vascularized resulting in good probability of complete excision
  • Perineal approach or pubic split is rarely required

+ Surgical Management – Malignant Tumors

  • Malignant infiltrative vaginal tumors treated with complete vulvovaginectomy and perineal urethrostomy
  • Sternal recumbency in perineal stand with perineum elevated
  • Urethra catheterized
  • Fusiform skin incision performed around vulva
  • Deeper tissues sharply dissected from labia and vestibule
  • Constrictor vestibuli and constrictor vulvae muscles are dissected from the vestibule
  • Dorsal labial branches of the ventral perineal artery are ligated or bleeding controlled with electrocautery
  • Catheterized urethra identified and dissected free from encircling constrictor vestibuli muscles

alt text From: Bilbrey SA, et al: Vulvovaginectomy and perineal urethrostomy for neoplasms of the vulva and vagina. Vet Surg 18:450-453, 1989.

  • Vagina dissected with transection of ischiocavernosus and ischiourethralis muscles
  • Dissection continued cranially between paired levator ani muscles to level of cervix
  • Vaginal branches of vaginal and uterine arteries and veins ligated
  • Vagina transected immediately caudal to cervix in intact bitches or cervix and uterine stump removed in spayed dogs
  • Deep tissues closed to reduce dead space
  • Perineal urethrostomy performed with transected urethra tractioned caudally, distal end spatulated, and closed in 2 layers with final layer mucosa to skin

alt text From: Bilbrey SA, et al: Vulvovaginectomy and perineal urethrostomy for neoplasms of the vulva and vagina. Vet Surg 18:450-453, 1989.

+ Prognosis

  • Complete surgical excision is usually curative
  • Guarded to poor prognosis with ADC, TCC, and SCC due to high local tumor recurrence and metastatic rates