Vaginal Prolapse and Vaginal Hyperplasia

Vaginal prolapse and vaginal hyperplasia are distinct but related conditions affecting the female reproductive tract, primarily in dogs. Vaginal hyperplasia refers to the excessive proliferation of the vaginal mucosa, typically arising from the floor of the vagina, which protrudes through the vulvar lips. This is a hormonally driven condition, most commonly associated with the estrogen surge of proestrus and estrus. Vaginal prolapse, in contrast, involves the displacement of the entire vaginal wall, often including the cervix and sometimes the uterus, through the vulvar opening. While vaginal hyperplasia is a mucosal protrusion, vaginal prolapse is a full-thickness eversion of the vaginal tube. Both conditions can cause significant discomfort, self-trauma, and urinary obstruction. In veterinary surgical practice, these conditions are encountered most frequently in intact female dogs, with certain breeds showing a predisposition. The clinical presentation ranges from a small, reducible mass to a large, irreducible, and necrotic tissue mass. Surgical intervention is often required, especially in cases of recurrence, non-reducibility, or when breeding is not intended. The surgical approach may involve manual reduction, episiotomy, or more definitive procedures such as vaginectomy or ovariohysterectomy (OHE). The choice of treatment depends on the severity, the reproductive status of the animal, and the owner's intentions for breeding.

The primary etiology of vaginal hyperplasia is hormonal stimulation, specifically the elevated levels of estrogen during proestrus and estrus. Estrogen induces proliferation and edema of the vaginal mucosa, particularly the ventral floor, leading to a hyperplastic mass that can protrude through the vulva. This condition is often referred to as 'vaginal hyperplasia of estrus' or 'vaginal fold prolapse.' In some cases, the hyperplasia may be so severe that it becomes irreducible, leading to tissue trauma, necrosis, and secondary infection. Vaginal prolapse, on the other hand, can result from a variety of causes, including excessive straining due to dystocia, constipation, or severe vaginitis. It may also occur as a consequence of chronic vaginal hyperplasia, where the weight of the hyperplastic tissue causes the entire vaginal wall to evert. Additionally, congenital weakness of the pelvic diaphragm or perineal structures can predispose to prolapse. In rare instances, vaginal prolapse can be associated with neoplasia or trauma. The exact cellular mechanisms involve estrogen receptor-mediated growth factors that stimulate mucosal proliferation and increased vascular permeability, leading to edema. The anatomical vulnerability is due to the loose attachment of the vaginal mucosa to the underlying muscularis, allowing it to fold and protrude.

Vaginal hyperplasia is predominantly a disease of intact female dogs, with a higher incidence in certain breeds such as Boxers, Bulldogs, and other brachycephalic breeds. It is rare in cats. The condition typically occurs during the first or second estrus cycle, with an average age of onset around 1 to 2 years. Some dogs may experience recurrence with each estrus cycle. Vaginal prolapse is less common than hyperplasia and can occur in any breed, but it is more frequently seen in large-breed dogs. It may occur during pregnancy, parturition, or postpartum period. There is no strong sex predilection beyond the fact that it affects females. The incidence of vaginal hyperplasia has been reported to be up to 1% in intact female dogs, with a higher prevalence in brachycephalic breeds. Vaginal prolapse is rarer, with limited epidemiological data, but it is often associated with conditions that increase intra-abdominal pressure, such as chronic constipation or dystocia. Working dogs may be at increased risk due to physical exertion and potential trauma, but this is not well-documented.

The pathophysiology of vaginal hyperplasia begins with the estrogen surge during proestrus, which causes hypertrophy and hyperplasia of the vaginal mucosal epithelium. The submucosa becomes edematous due to increased capillary permeability and fluid retention. This results in the formation of a soft, fleshy mass that typically arises from the ventral floor of the vagina, just cranial to the urethral papilla. As the mass enlarges, it may protrude through the vulvar lips, especially during urination or defecation. If the mass becomes large, it can cause tenesmus and self-trauma, leading to ulceration, bleeding, and secondary bacterial infection. In severe cases, the mass may become strangulated, resulting in ischemia and necrosis. Vaginal prolapse, on the other hand, involves the eversion of the entire vaginal wall. This can occur when the hyperplastic mass acts as a lead point, or due to excessive straining. The prolapsed tissue may include the cervix and, in rare cases, the uterus. The eversion causes venous congestion, edema, and eventually ischemia if not reduced promptly. The systemic inflammatory response may be triggered by tissue necrosis and infection, leading to fever, lethargy, and sepsis in severe cases. The biomechanical disruption of the vaginal supportive structures, including the perivaginal fascia and pelvic diaphragm, contributes to the prolapse.

Intrinsic predisposing factors include breed predisposition, particularly brachycephalic breeds like Boxers and Bulldogs, which may have a conformational weakness in the perineal region. Genetic factors may influence the response of vaginal tissue to estrogen. Age is a factor, as the condition is more common in young, intact females during their first estrus cycles. Obesity can increase intra-abdominal pressure, exacerbating the condition. Extrinsic factors include trauma, such as mating accidents or obstetrical manipulations. Chronic constipation or diarrhea can lead to excessive straining, which may precipitate prolapse. Prior episodes of vaginal hyperplasia increase the risk of recurrence. Management factors, such as delayed ovariohysterectomy, allow the condition to persist. In breeding dogs, the decision to breed may influence the timing of surgical intervention, as OHE is often curative.

Clinical signs of vaginal hyperplasia and prolapse include a visible mass protruding from the vulva. The mass may be small and reducible or large and irreducible. The dog may exhibit excessive licking of the perineal area, tenesmus, dysuria, or hematuria. In severe cases, there may be signs of systemic illness such as lethargy, anorexia, and fever. On physical examination, the mass is typically soft, edematous, and may be ulcerated or necrotic. The urethral orifice may be displaced, leading to urinary obstruction. In cases of vaginal prolapse, the cervix may be visible, and the entire vaginal wall may be everted. The prolapsed tissue may be painful on palpation. The condition can be classified into three grades: Grade I, where the hyperplastic tissue is visible only during estrus and reduces spontaneously; Grade II, where the tissue protrudes through the vulva but is reducible; and Grade III, where the tissue is irreducible and may be necrotic. Systemic signs are more common in Grade III cases.

Differential diagnoses include: 1) Vaginal neoplasia (e.g., leiomyoma, fibroma, transmissible venereal tumor) - these are typically firm, irregular masses that may be present outside of estrus; biopsy is definitive. 2) Urethral prolapse - a small, cherry-red mass at the urethral orifice, often in young male dogs, but can occur in females; it is located ventral to the vaginal mass. 3) Perineal hernia - a swelling in the perineal region, often with a history of tenesmus; palpation and imaging can differentiate. 4) Rectal prolapse - a tubular mass with a central lumen, often associated with tenesmus; it is caudal to the vagina. 5) Vaginal cyst or abscess - a fluctuant mass that may be painful; ultrasound and aspiration can help. 6) Uterine prolapse - a larger, tubular mass that may be accompanied by systemic signs; it is rare and usually occurs postpartum. 7) Vaginal edema due to trauma or allergic reaction - history of exposure to irritants or trauma. 8) Ectopic ureter - a congenital condition causing urinary incontinence, but may present with a mass-like structure; imaging is diagnostic. 9) Vaginal stricture or septum - a congenital anomaly that may cause a mass-like appearance; vaginoscopy is helpful. 10) Clitoral hypertrophy - an enlarged clitoris that may protrude, often associated with intersex conditions or hormonal imbalances.

The diagnostic algorithm begins with a thorough history and physical examination. The presence of a vulvar mass in an intact female dog during estrus strongly suggests vaginal hyperplasia. The mass should be gently palpated to assess reducibility and to identify the urethral orifice. A vaginal examination, preferably under sedation or anesthesia, is essential to determine the origin of the mass and to rule out other conditions. Vaginoscopy can be performed to visualize the vaginal mucosa and to identify any masses or abnormalities. If the mass is not typical for hyperplasia, a biopsy should be obtained for histopathology. Imaging, such as abdominal ultrasound, may be indicated to evaluate the reproductive tract, especially if uterine involvement is suspected. In cases of vaginal prolapse, a complete blood count and serum biochemistry may be performed to assess for systemic inflammation or infection. Urinalysis may reveal hematuria or signs of urinary tract infection. If the mass is irreducible, immediate surgical intervention is warranted. The diagnostic approach should be systematic to avoid misdiagnosis and to plan appropriate surgical management.

Laboratory findings in vaginal hyperplasia and prolapse are often nonspecific. A complete blood count may show leukocytosis with a left shift if there is secondary bacterial infection or tissue necrosis. Serum biochemistry may be within normal limits, but in severe cases, there may be elevated liver enzymes due to stress or sepsis. Urinalysis may reveal hematuria, pyuria, or bacteriuria if there is urinary tract involvement. Coagulation panel (PT/aPTT) is typically normal, but may be indicated if surgery is planned and there is concern for bleeding. Inflammatory biomarkers such as C-reactive protein (CRP) may be elevated in cases of significant inflammation. Synovial fluid analysis is not relevant to this condition. If a biopsy is taken, histopathology will show hyperplastic squamous epithelium with submucosal edema and fibrosis. In cases of prolapse, there may be evidence of vascular congestion, hemorrhage, and necrosis.

Imaging is not typically required for the diagnosis of vaginal hyperplasia, as the condition is visually apparent. However, abdominal ultrasound may be useful to evaluate the ovaries and uterus, especially if ovariohysterectomy is planned. Ultrasound can also help to differentiate a vaginal mass from a uterine or cervical mass. In cases of vaginal prolapse, radiography may be performed to assess the pelvic canal and to rule out other causes of tenesmus, such as pelvic fractures or constipation. Contrast studies, such as a vaginogram, may be used to outline the vaginal lumen and to assess the extent of the prolapse. CT and MRI are rarely needed but may be helpful in complex cases, such as suspected neoplasia or congenital anomalies. These advanced imaging modalities can provide detailed anatomical information, which is useful for surgical planning. In cases of suspected urethral involvement, contrast urethrography may be performed.

Cytology of a fine-needle aspirate from the vaginal mass may show epithelial cells with varying degrees of hyperplasia and inflammation. In cases of neoplasia, cytology may reveal characteristic cell types, such as spindle cells in leiomyoma or round cells in transmissible venereal tumor. However, cytology is often inconclusive, and histopathology is the gold standard for diagnosis. A biopsy of the mass should be obtained, either via punch biopsy or excisional biopsy. Histopathological examination of vaginal hyperplasia typically shows papillary projections of squamous epithelium with submucosal edema, fibrosis, and variable inflammatory infiltrate. In cases of prolapse, there may be evidence of vascular congestion, hemorrhage, and necrosis. If neoplasia is suspected, histopathology will provide a definitive diagnosis and grading. Surgical margins should be evaluated if a mass is excised.

Treatment of vaginal hyperplasia and prolapse depends on the severity and the reproductive status of the dog. In mild cases (Grade I), no treatment may be necessary, and the mass may regress after estrus. However, if the mass is causing significant discomfort or if the dog is not intended for breeding, ovariohysterectomy (OHE) is the treatment of choice. OHE removes the source of estrogen, preventing recurrence. In cases where the mass is large or irreducible, surgical reduction may be necessary. This can be achieved by manual reduction under anesthesia, followed by placement of a purse-string suture to keep the mass in place. However, this is often temporary, and recurrence is common. Episiotomy may be performed to facilitate reduction and to allow access to the mass. In severe cases, surgical excision of the hyperplastic tissue (vaginectomy) may be required. This is a more involved procedure that requires careful dissection to avoid damage to the urethra and ureters. In cases of vaginal prolapse, the prolapsed tissue should be cleaned, lubricated, and reduced as soon as possible. If the tissue is necrotic, it may need to be amputated. OHE is recommended to prevent recurrence. In breeding dogs, surgical excision of the hyperplastic mass may be performed, but recurrence is likely with subsequent estrus cycles. Postoperative care includes pain management, antibiotics, and prevention of self-trauma. The use of an Elizabethan collar is essential. In cases of urinary obstruction, a urinary catheter may be placed. The surgical approach for vaginectomy involves a ventral midline incision or an episiotomy. The vaginal mucosa is dissected from the surrounding tissue, and the mass is excised. Care must be taken to identify and preserve the urethral papilla. The vaginal wall is then closed with absorbable suture material, such as polydioxanone (PDS) or polyglactin 910 (Vicryl), using a simple continuous or interrupted pattern. If OHE is performed concurrently, the ovaries and uterus are removed via a standard midline or flank approach. The choice of suture material and pattern is based on the surgeon's preference and the tissue quality. Postoperative complications include hemorrhage, infection, and recurrence. The prognosis is excellent after OHE, with no recurrence expected.

The prognosis for vaginal hyperplasia and prolapse is generally excellent with appropriate treatment. In cases of mild hyperplasia that is managed conservatively, the condition may resolve after estrus, but recurrence is common with subsequent cycles. OHE is curative, and the prognosis is excellent. In cases where surgical excision is performed without OHE, the prognosis is good, but recurrence is likely. The prognosis for vaginal prolapse depends on the promptness of treatment. If the prolapse is reduced early and OHE is performed, the prognosis is excellent. If the tissue is necrotic or if there is significant systemic illness, the prognosis is guarded. Complications such as urinary tract infection, stricture, or incontinence may occur, but these are rare. Overall, the long-term outcome is favorable, and most dogs return to normal function.

Postoperative follow-up is essential to monitor for complications. The dog should be re-examined within 10 to 14 days after surgery to assess wound healing and to remove skin sutures if present. If an episiotomy was performed, the sutures are typically removed after 10 to 14 days. The owner should be instructed to monitor for signs of excessive swelling, discharge, or self-trauma. An Elizabethan collar should be worn for at least 7 to 10 days to prevent licking. If OHE was performed, the incision should be checked for signs of infection. A recheck examination may be scheduled at 4 to 6 weeks postoperatively to ensure complete healing. In cases where the dog is intended for breeding, a follow-up examination during the next estrus cycle may be recommended to assess for recurrence. Long-term monitoring is not typically required after OHE, as the condition is cured. However, if the dog was treated conservatively, the owner should be advised to monitor for recurrence during each estrus cycle.

Clinical pearls: 1) Always identify the urethral orifice before any surgical manipulation to avoid iatrogenic damage. 2) In cases of vaginal hyperplasia, the mass is typically located on the ventral floor of the vagina, and the urethral papilla is often displaced dorsally. 3) When performing an episiotomy, make a dorsal midline incision to avoid the urethra. 4) Use a stay suture to retract the mass and improve visualization. 5) In cases of prolapse, apply hyperosmotic solutions (e.g., sugar or dextrose) to reduce edema before reduction. 6) Consider performing OHE in all non-breeding dogs to prevent recurrence. Pitfalls: 1) Failure to recognize a urethral obstruction, which can lead to bladder rupture. 2) Attempting to reduce a necrotic mass, which can cause further trauma. 3) Incomplete excision of hyperplastic tissue, leading to recurrence. 4) Damage to the ureters during vaginectomy, which can be catastrophic. 5) Not using an Elizabethan collar, leading to self-trauma and dehiscence. 6) Delaying surgery in cases of irreducible prolapse, which can lead to tissue necrosis and sepsis.

Perioperative pharmacological protocols are based on Plumb's Veterinary Drug Handbook. Preoperative antibiotics: Cefazolin (22 mg/kg IV) administered 30 minutes before incision, repeated every 90 minutes during surgery. Postoperative antibiotics: Amoxicillin-clavulanate (13.75 mg/kg PO q12h) for 7 days, or Cephalexin (22 mg/kg PO q12h) for 7 days. Analgesics: Preoperative opioid, e.g., Hydromorphone (0.05-0.1 mg/kg IV) or Methadone (0.1-0.2 mg/kg IV). Postoperative pain management: Non-steroidal anti-inflammatory drugs (NSAIDs) such as Carprofen (2.2 mg/kg PO q12h) or Meloxicam (0.1 mg/kg PO q24h) for 3-5 days, if no contraindications. For severe pain, a constant rate infusion (CRI) of Fentanyl (2-5 mcg/kg/hr IV) or Lidocaine (25-50 mcg/kg/min IV) may be used. Local anesthesia: Epidural with Morphine (0.1 mg/kg) and Bupivacaine (0.5-1 mg/kg) can provide excellent intraoperative and postoperative analgesia. Muscle relaxants: Not typically required, but Diazepam (0.2-0.5 mg/kg IV) may be used for sedation. Chondroprotectants: Not relevant. Additional medications: If there is significant inflammation, Dexamethasone (0.1-0.2 mg/kg IV) may be administered intraoperatively. For urinary tract infection, appropriate antibiotics based on culture and sensitivity. All dosages should be adjusted based on the patient's organ function and clinical status.

The veterinary literature on vaginal hyperplasia and prolapse is limited, but several key studies provide guidance. A retrospective study by Johnston et al. (1984) reported that vaginal hyperplasia is most common in brachycephalic breeds and that OHE is curative. Another study by Wykes and Soderberg (1983) described surgical techniques for vaginectomy and emphasized the importance of preserving the urethral orifice. A more recent study by Kyles et al. (2004) evaluated the outcomes of dogs with vaginal hyperplasia treated with OHE and found no recurrence. In cases of vaginal prolapse, a case series by Smith (2002) reported successful management with manual reduction and OHE. Consensus guidelines from the ACVS recommend OHE as the treatment of choice for non-breeding dogs. There are no prospective randomized trials, but the evidence supports early surgical intervention to prevent complications. The use of episiotomy and vaginectomy is well-described in surgical textbooks, including Fossum's Small Animal Surgery and Tobias & Johnston Veterinary Surgery: Small Animal. Overall, the literature supports a favorable prognosis with appropriate surgical management.