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Basics ⬇

Outline

BASICS

Definition!!navigator!!

  • The quality/grade of VC is determined by the anatomic orientation of the anal sphincter to the vulva and pubis. This orientation impacts directly on the mare's reproductive health and affects her ability to maintain a healthy uterus and to carry pregnancies to term
  • Good VC—the dorsal commissure of the vulva is at or below the level of the floor of the pubic bone. This generally is coupled with vulvae that exhibit an efficient side-to-side seal and with no cranial slant, effectively protecting the genital tract from manure contamination or aspiration of air
  • Fair VC—the dorsal vulvar commissure is elevated above the floor of the pubis and/or the vulvar lips slope anteriorly, permitting pneumovagina or manure contamination of the vestibule
  • Poor VC—the dorsal vulvar commissure is elevated above the floor of the pubis. This usually is accompanied by an obvious anterior slant of the vulva. Manure contamination of the vestibule occurs frequently to continuously
  • Problems with VC are major contributors to equine subfertility and infertility

Pathophysiology!!navigator!!

Additional factors predisposing mares to poor VC—breeds/individuals with less muscle in the perineal area; perineal lacerations, and being underweight.

Systems Affected!!navigator!!

Reproductive

Genetics!!navigator!!

  • Influences VC (mother/daughter) and should be considered when selecting broodmares. This is particularly important if farm-born fillies are kept for replacement stock
  • Mares with good VC have fewer reproductive problems

Incidence/Prevalence!!navigator!!

  • Abnormal VC can affect all breeds, but is especially common in racing breeds, e.g. Thoroughbreds and Standardbreds
  • More muscular breeds or certain families within breeds have less of a problem with compromised VC

Signalment!!navigator!!

  • All breeds and any stock of breeding age
  • Incidence of poor VC increases in old, pluriparous mares

Signs!!navigator!!

General Comments

  • The condition is fairly easy to evaluate. Assessment of each broodmare's VC should be noted on her record at the start of each breeding season
  • Can worsen with age

Historical Findings

  • History of subfertility or infertility because of failure to conceive or termination of pregnancy
  • In addition to endometritis, vaginitis or cervicitis may be present

Physical Examination Findings

  • Less than ideal VC may result in gross/histopathologic changes of the tubular genital tract, e.g. endometritis, acute or chronic
  • Transrectal palpation—enlargement of uterine horns, increased uterine size, intraluminal fluid accumulation, and aspiration of air (e.g. pneumovagina, pneumouterus); if severe, echogenicities identified at ultrasonography may be caused by manure aspiration into the uterus
  • Vaginal examination using sterile lubricant and a sterile vaginal speculum may reveal inflammation, discharge (e.g. endometritis, cervicitis, vaginitis), urine pooling, and/or adhesions (if chronic)
  • Other physical parameters usually are normal

Causes!!navigator!!

  • Inherited poor VC
  • Perineal laceration resulting from abnormal posture or fetal position at parturition
  • Vaginal or vestibular intrapartum injuries caused by the fetus' feet (extremities) penetrating the dam's tract, e.g. causing tears/damage to the wall of her caudal tubular tract

Risk Factors!!navigator!!

  • Inherited
  • No specific risk factors other than compromising the mare's ability to carry a healthy pregnancy to term
  • Posterior presentation of a fetus, hindlimbs extended, has the potential to cause perineal lacerations
  • Fetal posture and position can change within minutes of birth, so previous examinations for fetal position and posture have little predictive value

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Differential Diagnosis!!navigator!!

N/A

CBC/Biochemistry/Urinalysis!!navigator!!

N/A

Other Laboratory Tests!!navigator!!

N/A

Imaging!!navigator!!

N/A

Other Diagnostic Procedures!!navigator!!

  • Determine the location of the dorsal vulvar commissure in relation to the pubis
  • Careful palpation of the vestibule, vagina, and rectum to identify lacerations
  • Rectovaginal fistulas may be small and not readily identified but result in sufficient contamination of the uterus to affect fertility

Pathologic Findings!!navigator!!

  • Partial- to full-thickness lacerations of the vestibule and/or vagina
  • Aspiration of air into the vagina and/or uterus
  • Fecal contamination of the vagina and vestibule, with resulting inflammation of the vestibule, vagina, and cervix, and, possibly, the endometrium

Treatment ⬆ ⬇

Outline

TREATMENT

Appropriate Health Care!!navigator!!

  • Determine that a laceration does not extend into the peritoneal cavity; rare with perineal laceration or rectovaginal fistula
  • Systemic antibiotics seldom are indicated
  • Local medication is rarely indicated
  • Repair lacerations before attempting rebreeding
  • Boost tetanus toxoid vaccination, if status is not current or is unknown

Nursing Care!!navigator!!

N/A

Activity!!navigator!!

Normal activity, no restrictions.

Diet!!navigator!!

Normal; no restrictions.

Client Education!!navigator!!

  • Review importance of closely observing foaling
  • Many lacerations occur before a foaling problem is noticed, even with trained attendants

Surgical Considerations!!navigator!!

  • Surgical correction for poor VC (episioplasty) was first described by Caslick in 1937, i.e. Caslick's vulvoplasty
  • First, wrap and tie the mare's tail away from the field of surgery, and thoroughly clean the perineal area with cotton and soap
  • Mepivacaine (Carbocaine) or another local anesthetic is infiltrated into the mucocutaneous junction of the vulva; ≅10–12 mL can be used to infiltrate both sides of the vulvar lips
  • The tissue edges are freshened before suturing, either by removing a very narrow strip of tissue from the edge or by incising the mucocutaneous junction with a no. 10 scalpel blade in a upside down “U” shape:
    • The edges of the vulvar lip that have been dilated with local anesthetic open into a nice, approximately 1 cm wide incision
    • The split-thickness technique results in no tissue removal, i.e. it is tissue sparing, in that it helps to retain the normal elasticity of the vulva during labor

It minimizes damage that can be attributed to an annual vulvoplasty. Both described techniques can be used, however, and are acceptable

  • Use nonabsorbable suture material, e.g. no. 1 Braunamid, or staples (increase likelihood of fistula formation), with removal in no less than 10 days
  • Mares will often have sutures left in until they are examined for pregnancy at 15–16 days to avoid 1 extra trip to the barn
  • Ensure adequate mare's tetanus toxoid vaccination status
  • Pouret technique—in cases of severe/extremely poor VC, it may be necessary to dissect the perineal body in a caudal (widest) to cranial (point), pie-shaped wedge to permit the genital tract that lies ventral to the rectum to slide caudally and away from manure contamination, as well as aspiration of air. Only the skin is closed (i.e. no deep reconstruction of dissected tissue)
  • Vestibuloplasty is described as creating an artificial vestibular valve; some success reported in resolving chronic, persistent pneumovagina. The repair is constructed within 2 days following breeding and ovulation. Using either a 1- or 2-step procedure, an upside down U-shaped incision is made, beginning at the dorsum of the vestibule, dissecting subcutaneous tissue sufficiently to suture together the edges from the left and right, leaving at least a 2 cm opening for urination

Medications ⬆ ⬇

Outline

MEDICATIONS

Drug(s) of Choice!!navigator!!

  • No antibiotics are indicated
  • Selection of local anesthetic is at the discretion of the surgeon

Contraindications!!navigator!!

N/A

Precautions!!navigator!!

N/A

Possible Interactions!!navigator!!

N/A

Alternative Drugs!!navigator!!

N/A

Follow-up ⬆ ⬇

Outline

FOLLOW-UP

Patient Monitoring!!navigator!!

Suture removal 10–15 days after surgery to prevent the possibility of stitch abscesses at the suture site.

Prevention/Avoidance!!navigator!!

Select broodmares with excellent VC.

Possible Complications!!navigator!!

  • Primary contraindication for vulvoplasty is the necessity of reopening the vulvar commissure ≅5–10 days before parturition to prevent the perineum from tearing at delivery
  • Failure to place a vulvoplasty after breeding and a confirmed ovulation, if it is necessary, may preclude the mare conceiving or carrying a pregnancy to term
  • Caslick's vulvoplasty should be replaced (i.e. incised and sutured) immediately after foaling, or breeding and confirmation of ovulation in the next season, depending on the severity of VC

Expected Course and Prognosis!!navigator!!

Without surgical correction, mares may remain infertile or abort during pregnancy.

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Associated Conditions!!navigator!!

N/A

Age-Related Factors!!navigator!!

High probability of this condition worsening with age.

Zoonotic Potential!!navigator!!

N/A

Pregnancy/Fertility/Breeding!!navigator!!

Surgery may be necessary to obtain a pregnancy

Synonyms!!navigator!!

Wind sucker

Abbreviations!!navigator!!

VC = vulvar conformation

Suggested Reading ⬆ ⬇

Caslick EA. The vulva and vulvo-vaginal orifice and its relationship to genital health of the Thoroughbred mare.Cornell Vet 1937;27:178–186.

Inoue Y, Sekiguchi M. Vestibuloplasty for persistent pneumovagina in mares. J Equine Vet Sci 2017;48:9–14.

Stickle RL, Fessler JF, Adams SB, et al. A single stage technique for repair of rectovestibular lacerations in the mare. J Vet Surg 1979;8:25–27.

Author(s) ⬆

Author: Carla L. Carleton

Consulting Editor: Carla L. Carleton

Acknowledgment: The author/editor acknowledges the prior contribution of Walter R. Threlfall.