Rectovaginal Fistula

Rectovaginal fistula in mares is an abnormal communication between the rectum and vagina that develops as a consequence of traumatic injury during parturition. This pathological opening allows passage of fecal material from the rectum directly into the vaginal vault, causing severe contamination of the reproductive tract that precludes successful breeding without surgical correction. The condition most commonly results from foal foot penetration through the dorsal vaginal wall and rectal floor during delivery, creating a persistent defect that cannot heal spontaneously due to continuous fecal contamination and mechanical disruption.

Rectovaginal fistulas occur with variable frequency in equine breeding populations, with first-time foaling mares at particularly elevated risk due to their smaller pelvic dimensions and less accommodating soft tissues. The condition may develop during apparently normal deliveries when fetal positioning or movement causes localized trauma, or may occur as part of more extensive perineal injuries during dystocia that requires assisted delivery. While some fistulas are immediately apparent following foaling due to obvious tissue disruption, smaller defects may not be detected until the acute post-partum swelling subsides and fecal contamination of the vagina becomes evident.

The impact of rectovaginal fistula on a mare's reproductive function is profound, as the continuous passage of fecal material into the vaginal vault creates chronic inflammation and infection that completely prevents successful conception. Beyond reproductive implications, affected mares experience discomfort from chronic tissue irritation and may develop secondary complications including ascending urinary tract infections, chronic vaginitis, and potentially pyometra if the cervix closes and traps contaminated material. The psychological and welfare impact on affected mares includes chronic irritation, abnormal posturing, and behavioral changes reflecting ongoing discomfort.

Fortunately, rectovaginal fistula is surgically correctable in most cases, with well-established techniques providing good to excellent success rates when performed by experienced equine surgeons after appropriate tissue healing has occurred. The condition requires delayed surgical intervention to allow resolution of post-partum inflammation and development of well-defined wound margins that will hold sutures effectively. With proper timing, technique, and post-operative management, most mares can return to successful breeding following fistula repair, though some may experience reduced fertility or require additional procedures to address concurrent reproductive tract damage.

The primary cause of rectovaginal fistula is traumatic penetration of the dorsal vaginal wall and ventral rectal wall by fetal extremities during parturition. During normal delivery, the foal's forefeet and nose should present in a diving position that follows the natural curvature of the birth canal. When fetal positioning is abnormal, or when the foal extends its limbs prematurely or inappropriately, the sharp hoof edges can tear through the soft tissue barrier separating the vagina from the rectum. This penetrating injury creates an immediate communication between the two passages that becomes a persistent fistula if not recognized and addressed immediately.

Genetic and conformational factors influence fistula risk primarily through their effects on pelvic dimensions and birth canal capacity. Mares with relatively narrow pelvic outlets may experience greater tissue tension during foaling, increasing vulnerability to laceration. Breed considerations include the fact that miniature horses and small pony breeds delivering proportionally large foals face heightened risk. Additionally, mares being bred to stallions known to produce large-bodied foals may experience increased foaling difficulty and associated trauma risk. However, rectovaginal fistula can occur in any mare regardless of size or breed when specific inciting circumstances arise.

Environmental and management factors during the foaling process significantly influence fistula development risk. Unattended deliveries prevent immediate intervention when malpresentation or difficulty occurs, allowing prolonged trauma that increases tissue damage severity. Inappropriate intervention by inexperienced attendants who do not recognize fetal positioning problems or who apply excessive traction before correcting malpresentation can cause or worsen lacerations. Conversely, skilled obstetric assistance that quickly identifies and corrects abnormal presentations can prevent fistula development even in difficult deliveries.

Risk factors for rectovaginal fistula development include primiparity, fetal oversize, malpresentation, and rapid or explosive delivery. First-foaling mares have less elastic reproductive tissues and smaller accommodated pelvic dimensions, increasing laceration risk. Foals that are large relative to the mare's pelvis create excessive tissue tension during passage. Abnormal presentations including limb flexion, head deviation, or posterior presentation increase the likelihood of foot penetration injuries. Deliveries that proceed very rapidly may not allow adequate tissue relaxation between contractions, while explosively rapid second-stage labor may cause uncontrolled tissue tearing.

The pathophysiology of rectovaginal fistula involves initial traumatic tissue disruption followed by failure of spontaneous healing due to continuous fecal contamination and mechanical forces. When fetal extremities penetrate the rectovaginal septum, the resulting defect exposes vaginal tissues to constant contact with feces, preventing the formation of healthy granulation tissue necessary for wound closure. Each passage of fecal material through the fistula introduces bacteria into the reproductive tract while mechanically disrupting any early healing attempts. Without surgical intervention to create clean wound margins and protect the repair from contamination, the fistula remains patent indefinitely.

Early recognition of rectovaginal fistula typically occurs in the immediate post-partum period when astute attendants notice abnormal anatomy or bleeding patterns during foaling. Careful examination of the mare's perineal region following delivery may reveal obvious tissue disruption, with visible laceration extending from the vaginal vault through the vestibule and potentially involving the rectal floor. Fresh hemorrhage from torn tissues, asymmetric vulvar anatomy, and visible communication between vaginal and rectal passages indicate significant perineal trauma requiring veterinary evaluation. Some fistulas are immediately apparent, while others may be partially concealed by swelling and require careful examination for detection.

Vaginal contamination with fecal material represents the hallmark symptom of established rectovaginal fistula and becomes evident within days of foaling as acute swelling subsides. Owners and caretakers may observe feces-contaminated discharge from the vulvar opening, often with characteristic odor indicating gastrointestinal content mixing with reproductive tract secretions. The degree of visible contamination varies with fistula size and fecal consistency, with larger defects allowing passage of formed fecal balls while smaller fistulas may permit only liquid or pasty material. Tail soiling with mixed fecal and vaginal discharge provides visual evidence of the abnormal communication.

Behavioral changes in mares with rectovaginal fistula reflect discomfort from chronic tissue irritation and inflammation. Affected mares may demonstrate frequent posturing to urinate without producing urine, reflecting vulvar and vestibular irritation rather than urinary dysfunction. Tail rubbing against fences, stalls, or other objects indicates perineal discomfort and attempts to relieve irritation. Some mares show decreased appetite, general malaise, or reluctance to defecate due to discomfort associated with fecal passage through the damaged tissues. Changes in normal behavior patterns and reduced interaction with herd mates may indicate chronic pain and distress.

Physical examination findings in mares with rectovaginal fistula reveal the abnormal communication between rectal and vaginal passages. Digital examination through the vagina readily identifies the fistulous opening in the dorsal vaginal wall, with simultaneous rectal palpation confirming the corresponding defect in the rectal floor. The size and location of the fistula can be precisely characterized, informing surgical planning. Vaginal speculum examination reveals fecal contamination of the vaginal vault and often shows inflammation of vaginal tissues from chronic exposure to gastrointestinal contents. Examination also assesses concurrent injuries including perineal body damage, anal sphincter involvement, and vestibular lacerations.

Symptom progression in untreated rectovaginal fistula involves establishment of chronic inflammation and secondary complications. Initial acute swelling and pain give way to chronic tissue changes as the fistula matures and wound margins become well-defined. Chronic vaginitis develops from continuous fecal contamination, potentially ascending to involve the cervix and uterus. Weight loss may occur as mares reduce feed intake due to discomfort or develop secondary health issues. Some mares develop urinary tract infections from contamination of the vestibulovaginal region with fecal bacteria.

Emergency symptoms requiring immediate veterinary attention in the post-partum mare include massive perineal hemorrhage, signs of shock, severe straining, rectal prolapse, or evidence of intestinal exposure through extensive wounds. While rectovaginal fistula itself is not immediately life-threatening, concurrent injuries sustained during the same traumatic delivery may require emergency intervention. Any mare that has experienced a difficult delivery should receive thorough post-partum examination to identify all injuries, as smaller fistulas may be overlooked while attention focuses on more obvious damage.

Physical examination provides definitive diagnosis of rectovaginal fistula through direct visualization and palpation of the abnormal communication. Following adequate restraint and appropriate sedation if needed, the examining veterinarian performs combined vaginal and rectal examination to identify and characterize the defect. The fistulous opening can be visualized through vaginal speculum examination as a discrete defect in the dorsal vaginal wall, often with visible fecal contamination emanating from the opening. Simultaneous rectal palpation confirms the corresponding defect in the rectal floor and assesses surrounding tissue integrity and thickness.

Diagnostic characterization of rectovaginal fistula involves assessment of fistula size, location, and associated tissue damage that guides surgical planning. Small fistulas may be only one to two centimeters in diameter, while extensive injuries can involve substantial portions of the rectovaginal septum. Location relative to the cervix, vestibulovaginal junction, and anal sphincter influences surgical approach selection. The veterinarian evaluates the perineal body for concurrent damage, as combined fistula and perineal body injury requires coordinated repair. Tissue quality assessment determines whether adequate tissue margins exist for primary closure or whether tissue advancement techniques will be necessary.

Advanced diagnostic evaluation may include assessment of concurrent reproductive tract damage and overall mare health status. Transrectal ultrasonography can evaluate uterine involution and identify post-partum complications such as retained fetal membranes or metritis that require treatment before fistula repair. Complete blood count and serum chemistry help assess inflammatory status and identify systemic effects of chronic infection. Endometrial culture and biopsy may be performed once the fistula is repaired to evaluate residual effects of chronic contamination on fertility potential.

Differential diagnosis for vaginal contamination with fecal material primarily involves distinguishing between rectovaginal fistula and third-degree perineal laceration, which represents a more extensive injury pattern. Third-degree perineal lacerations destroy the entire rectovaginal septum, perineal body, and often the anal sphincter, creating a single common opening rather than a discrete fistula through an otherwise intact septum. The distinction is important because surgical repair approaches differ significantly between these injury types. Other considerations include pneumovagina with severe fecal contamination, though this lacks the direct anatomical communication characteristic of true fistula.

Immediate treatment following recognition of rectovaginal fistula focuses on supportive care while allowing appropriate tissue healing before surgical intervention. Fresh injuries are typically managed conservatively rather than attempting immediate repair, as post-partum tissue swelling, bruising, and fragility preclude successful primary closure. The mare should receive appropriate pain management, tetanus prophylaxis if vaccination status is uncertain, and prophylactic antimicrobial therapy to prevent ascending reproductive tract infection. Dietary modification to produce softer feces reduces trauma during defecation and minimizes mechanical disruption of healing tissues.

Medical management during the waiting period before surgical repair emphasizes maintaining tissue health and preventing secondary complications. Regular gentle cleaning of the perineal region removes accumulated fecal material and discharge while avoiding additional tissue trauma. Topical treatments may be applied to protect exposed tissues and promote healthy granulation tissue formation. Systemic anti-inflammatory medications help control pain and reduce tissue swelling. The veterinarian monitors for signs of infection, uterine contamination, or other complications that require additional intervention.

Surgical repair of rectovaginal fistula is performed after adequate healing time, typically four to eight weeks post-injury, when tissue swelling has resolved and wound margins are well-defined and healthy. Multiple surgical techniques exist, with selection based on fistula characteristics, surgeon preference, and concurrent injury patterns. Common approaches include direct closure with mucosal apposition after freshening wound margins, rectal mucosal advancement flaps to cover the defect, and split-thickness grafting techniques. The surgery is typically performed under standing sedation with epidural anesthesia, though some surgeons prefer general anesthesia for complex repairs.

Post-operative care following fistula repair critically influences surgical success by protecting the repair site during healing. Dietary modification to produce very soft feces continues for several weeks, often achieved through complete pelleted feeds or mash diets that minimize fecal bulk and straining during defecation. Fecal softeners and laxatives may be administered to further reduce mechanical stress on the repair. Antimicrobial therapy continues to prevent infection that could compromise healing. The mare should be confined to a clean stall with limited movement during initial healing, with gradual return to normal activity as the repair matures.

Rehabilitation and return to breeding function follows successful surgical repair and confirmation of fistula closure. The surgical site should be examined at regular intervals during healing to assess repair integrity and identify any early signs of dehiscence requiring intervention. Once complete healing is confirmed, typically eight to twelve weeks post-surgery, the mare may return to normal management. Breeding should be delayed until at least one estrous cycle has passed without breeding to allow final tissue maturation. Pre-breeding reproductive examination including culture and cytology confirms the reproductive tract has recovered from chronic contamination and is suitable for breeding.

Treatment decision factors include mare value, intended future use, fistula complexity, and concurrent injuries. Valuable broodmares warrant investment in skilled surgical repair and patient rehabilitation to preserve reproductive function. Mares with extensive concurrent injuries including third-degree perineal lacerations and anal sphincter damage require more complex reconstruction with less certain outcomes. Some owners may elect for palliative management rather than surgical repair in mares not intended for breeding, though chronic fistula maintenance requires ongoing care to manage complications and maintain mare comfort.

Recovery timeline for mares undergoing rectovaginal fistula repair extends over several months from initial injury to confirmed breeding soundness. The mandatory four to eight week waiting period before surgery allows acute inflammation to resolve and wound margins to mature. Following surgical repair, primary healing of the reconstruction typically occurs over three to four weeks, though complete tissue strength requires two to three months to develop. Total time from injury to return to breeding typically spans four to six months minimum, with some mares requiring longer rehabilitation periods especially following revision surgery for initial repair failure.

Post-treatment care and monitoring during recovery emphasize protecting the surgical repair while supporting overall mare health and reproductive tract recovery. Daily visual assessment of the perineal region identifies any discharge, swelling, or signs of repair breakdown requiring veterinary attention. Fecal consistency should be monitored to ensure dietary modifications are adequately softening stool to reduce strain on the repair site. The mare should be maintained in a clean, well-bedded environment that minimizes perineal contamination. Activity restriction continues until veterinary examination confirms adequate repair healing, typically at three to four weeks post-surgery.

Prognosis factors for rectovaginal fistula repair success include fistula size and location, tissue quality at time of surgery, surgical technique, and post-operative care compliance. Small fistulas with well-vascularized surrounding tissue and adequate margins for closure carry excellent prognosis, with first-time repair success rates exceeding eighty percent in experienced hands. Large fistulas, poor tissue quality from chronic inflammation, and concurrent injuries reduce success rates. Strict adherence to post-operative dietary modification and activity restriction significantly influences outcomes, as repair failure often results from excessive mechanical stress on the healing reconstruction.

Long-term reproductive outlook for mares following successful rectovaginal fistula repair is generally favorable, though fertility may be somewhat reduced compared to uninjured mares. Most mares that achieve complete fistula closure without complications can conceive and carry pregnancies successfully. However, chronic reproductive tract contamination may have caused endometrial changes that affect conception rates or pregnancy maintenance. Additionally, mares that have experienced difficult deliveries causing fistula formation may be at increased risk for subsequent foaling complications. Some veterinarians recommend Caslick's procedure following repair to protect the reproductive tract during subsequent breeding and pregnancy.

Management practices focused on optimal foaling supervision provide the most effective prevention for rectovaginal fistula development. Mares approaching parturition should be monitored closely, preferably with video surveillance or regular checks, to ensure rapid identification of delivery difficulties. Experienced foaling attendants can recognize malpresentation early and provide appropriate intervention before significant tissue trauma occurs. Having veterinary contact information readily available and understanding when to call for professional assistance prevents escalation of manageable difficulties into severe injuries requiring extensive repair.

Breeding management practices that minimize dystocia risk contribute to fistula prevention. Mare and stallion selection should consider relative size matching to avoid producing foals that are excessively large for the mare's pelvic capacity. First-time mothers may benefit from breeding to stallions known to produce moderate-sized foals. Nutritional management during pregnancy should maintain appropriate body condition without excessive weight gain that could increase fetal size. Adequate exercise throughout pregnancy helps maintain maternal fitness and may facilitate easier delivery.

Education and preparation for foaling represent essential prevention components. Mare owners and managers should understand normal foaling progression and recognize signs of difficulty requiring intervention. Basic obstetric skills including assessment of fetal presentation and appropriate repositioning techniques should be learned before foaling season. Understanding when professional assistance is needed, rather than attempting extended intervention without adequate skill, prevents well-intentioned but harmful manipulation that worsens injuries.

Environmental factors in fistula prevention include providing appropriate foaling facilities that allow safe delivery with adequate space for mare movement and attendant access. Non-slip, clean footing reduces risk of maternal injury during delivery. Adequate lighting enables proper observation and intervention when needed. Having necessary supplies including obstetric lubricant, clean water, and appropriate restraint equipment readily available facilitates skilled assistance when difficulties arise. Foaling stalls should be large enough to allow the mare to move naturally while providing safe access for attendants.

Post-delivery examination protocols help identify injuries early when intervention can minimize long-term consequences. Every mare should receive careful perineal examination following foaling to identify lacerations, hematomas, or other injuries requiring attention. Early recognition of small fistulas or partial-thickness injuries allows appropriate management before complications develop. Documentation of foaling difficulty and any interventions required provides valuable information for future breeding decisions and management of subsequent pregnancies.

Daily management adjustments for mares with unrepaired rectovaginal fistula or those recovering from surgical correction focus on maintaining cleanliness and monitoring for complications. Mares with open fistulas require regular perineal cleaning to remove accumulated fecal material and discharge while avoiding additional tissue irritation. Gentle washing with warm water and mild soap followed by thorough drying helps maintain skin health around the vulva and prevent secondary infections. Tail wrapping or braiding reduces contamination accumulation and facilitates cleaning access. Fly control becomes particularly important as fecal and vaginal discharge attract insects that cause irritation and potentially introduce additional bacteria.

Housing and turnout considerations for affected mares balance the need for cleanliness with exercise and social interaction benefits. During post-surgical recovery, stall confinement in clean, well-bedded environments protects the repair site and facilitates monitoring. Once initial healing occurs, gradual return to small paddock turnout provides exercise while maintaining relatively clean conditions and preventing excessive physical activity. Group turnout should be delayed until the repair is fully healed to prevent injury from herd dynamics. Mares with chronic unrepaired fistulas may be maintained in standard conditions with enhanced attention to perineal hygiene.

Exercise modifications during fistula management vary with treatment status and recovery stage. Mares awaiting surgical repair may maintain normal exercise levels as tolerated, though some reduction may be appropriate if significant tissue swelling or discomfort exists. Following surgical repair, strict rest is required initially, progressing to hand-walking, small paddock turnout, and eventually normal activity as healing advances. The surgeon provides specific guidelines based on repair complexity and healing progress. Mares with chronic unrepaired fistulas may exercise normally, though monitoring for excessive irritation or complications should continue.

Monitoring and ongoing care for mares with fistula history continues throughout their reproductive careers. Following successful repair, regular examination confirms continued closure and absence of recurrence. Pre-breeding evaluation should include careful assessment of the repair site and reproductive tract health. During subsequent pregnancies, monitoring for any changes to the repaired area helps identify potential problems before delivery. Post-foaling examination following subsequent deliveries assesses whether the repair tolerated parturition without damage and identifies any new injuries requiring attention.

Quality of life and use considerations for mares with rectovaginal fistula depend on treatment success and intended future use. Successfully repaired mares can typically return to full breeding function and experience normal quality of life. Those with chronic unrepaired fistulas experience ongoing irritation and contamination that affects welfare, though the condition itself is not life-threatening. Mares not intended for breeding may be candidates for permanent fistula repair to eliminate chronic contamination and improve comfort, though the investment may be difficult to justify economically for non-breeding animals.

Rectovaginal fistula demonstrates increased incidence in miniature horses and small pony breeds due to the biomechanical challenges of delivering proportionally large foals through relatively small pelvic openings. These breeds often produce foals that are large relative to maternal size, creating significant tissue tension during delivery that increases laceration risk. Additionally, first-time foaling in these small breeds may be particularly risky as the maiden reproductive tract has not previously been stretched to accommodate delivery. Owners of miniature horses and small ponies should ensure experienced supervision during foaling and maintain low thresholds for veterinary assistance when any difficulty is noted.

Beyond breed considerations, individual mare factors influence fistula risk more significantly than genetic background. Primiparous mares of any breed face elevated risk due to their inexperienced and less accommodating reproductive tissues. Mares with relatively narrow pelvic dimensions, identifiable through breeding soundness examination, may be at increased risk regardless of breed. Those being bred to stallions known to produce large foals should receive enhanced foaling supervision. Previous foaling difficulty or reproductive tract injury also increases risk for subsequent deliveries.

Genetic testing and specific breeding recommendations for rectovaginal fistula prevention are not available since the condition results from traumatic injury rather than inherited defects. However, breeding management decisions should consider factors that influence dystocia risk, including maternal and paternal contribution to foal size. Selection of stallions producing moderate-sized foals may reduce difficulty for mares with borderline pelvic capacity. Documentation of foaling outcomes helps identify mares that consistently experience difficult deliveries and may benefit from enhanced supervision or consideration of surrogate use for valuable genetics.

Commonly co-occurring conditions with rectovaginal fistula include third-degree perineal lacerations, perineal body damage, and anal sphincter injuries, as these structures often sustain concurrent damage during the same traumatic delivery event. Third-degree perineal lacerations represent more extensive injuries that destroy the entire rectovaginal septum and perineal body, creating a single common opening rather than a discrete fistula. Anal sphincter disruption, often accompanying third-degree tears, results in fecal incontinence that requires specific repair considerations. Cervical and vaginal lacerations may also occur during difficult deliveries and require concurrent treatment.

Conditions with similar presenting signs that must be distinguished from rectovaginal fistula include pneumovagina with severe fecal contamination and chronic vestibulitis. Pneumovagina allows aspiration of environmental material including feces into the vaginal vault through poor vulvar seal, but lacks the direct anatomical communication characteristic of true fistula. Careful examination distinguishes between these conditions by identifying whether a fistulous opening exists or whether contamination enters through the vulvar opening. Chronic vestibulitis from other causes may produce similar discharge patterns but examination reveals intact rectovaginal septum.

Potential complications of rectovaginal fistula include chronic endometritis, pyometra, urinary tract infection, and surgical repair failure. Chronic contamination of the reproductive tract leads to persistent uterine infection that severely compromises fertility even after fistula repair. Secondary pyometra may develop if the cervix closes and traps contaminated material within the uterus. Ascending urinary tract infections occur when fecal bacteria contaminate the vestibulovaginal region. Surgical repair failure requiring revision surgery occurs in approximately fifteen to twenty percent of cases, particularly with large or complex defects.