section name header

Basics ⬇

Outline

BASICS

Definition!!navigator!!

Air in the vagina or uterus. Usually results from VC defect.

Pathophysiology!!navigator!!

  • Air accumulates subsequent to poor VC and relaxation of the vestibular sphincter
  • Negative pressure within the genital tract's lumen aids movement of air into the vestibule, vagina, uterus; eliciting a “windsucking” sound
  • With motion, air is forced back out; can hear a characteristic expulsive sound

Systems Affected!!navigator!!

Reproductive

Genetics!!navigator!!

Possibly influencing VC conformation.

Incidence/Prevalence!!navigator!!

Common

Signalment!!navigator!!

  • All breeds, but individuals with less perineal muscle more severely affected
  • Older pluriparous mares most commonly affected

Signs!!navigator!!

General Comments

Described in 1937 by Dr. Caslick and remains a major cause of infertility.

Historical Findings

  • May exhibit signs of chronic pneumovagina coupled with abnormal VC
  • Subfertility/infertility linked with uterine infections and/or inflammation

Physical Examination Findings

  • Determine if VC is normal:
    • Assess relationship of dorsal vulvar commissure to the pubic floor; should lie at or below the floor of the pubis
  • Effect of poor VC on fertility is confirmed by the presence of vaginitis, pneumovagina, or pneumouterus
  • As age/parity increases:
    • Anus is pulled cranially; attached to related soft tissue structures
    • The vulva is pulled in a cranial slant, up over the posterior brim of the pubis

Causes!!navigator!!

Predisposing Factors

  • Changes in general conformation, e.g. sway back
  • Loss of vaginal fat
  • Stretching of the supporting soft tissue structures in the perineal area

Risk Factors!!navigator!!

  • Repeated pregnancies
  • Poor nutritional condition

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Imaging!!navigator!!

Ultrasonography—unnecessary, unless to confirm pneumouterus.

Pathologic Findings!!navigator!!

  • Evidence of vaginitis and endometritis
  • Subfertility, infertility
  • May predispose to abortion after vaginitis and cervicitis develop

Treatment ⬆ ⬇

Outline

TREATMENT

Appropriate Health Care!!navigator!!

Little justification to treat a mare for a uterine infection/inflammation if poor VC is left uncorrected.

Client Education!!navigator!!

Advise clients to critically evaluate the VC of all mares; perform a vulvoplasty if needed.

Surgical Considerations!!navigator!!

  • Wrap and tie the mare's tail and clean the perineal area
  • Local anesthetic into the mucocutaneous junction of the vulva; ≅10–12 mL typically used to infiltrate each side of the vulva; the dorsal portion of the “U” is particularly sensitive
  • The tissue edges are freshened/incised in an upside-down “U”: left and right vulvar lip and connecting the 2 in an arc, across the dorsal commissure. 2 methods:
    • Strip removal—very narrow strip of tissue is cut from the edge of each vulvar lip, or
    • Split-thickness technique—incising at the mucocutaneous junction along the line dilated with local anesthetic, i.e. no tissue is removed. The latter results in less vulvar scarring; preferred for the long-term reproductive welfare of the mare
    • Both techniques are in use and considered acceptable
  • Nonabsorbable suture material (e.g. no. 1 Braunamid), Ford interlocking pattern allows tension adjustment along its length
    • At the time of suture removal, evaluate surgical site for presence of small fistulas through which contamination may continue. If present, repair at that time
  • Pouret technique for severe/extremely poor VC—dissect the perineal body in a caudal (widest) to cranial (point) pie-shaped wedge that permits the tubular genital tract, ventral to the rectum, to slide caudally and away from the anal sphincter. Only the skin is closed, i.e. no deep reconstruction of dissected tissue
  • Gadd procedure, aka deep Caslick, is a technique to reconstruct a torn perineal body
  • Check mare's tetanus toxoid vaccination status

Medications ⬆ ⬇

MEDICATIONS

Drug(s) of Choice

No antibiotics are indicated.

Follow-up ⬆ ⬇

Outline

FOLLOW-UP

Patient Monitoring!!navigator!!

Remove sutures 10–14 days after surgery.

Prevention/Avoidance!!navigator!!

Select broodmares with excellent VC.

Possible Complications!!navigator!!

Necessary to open the vulvar commissure ≅5–10 days prepartum to prevent perineal tearing at delivery. The Caslickls should be replaced, immediately after foaling, or breeding and confirmation of ovulation in the next season, depending on the severity of the mare's VC.

Expected Course and Prognosis!!navigator!!

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

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Age-Related Factors!!navigator!!

High probability of VC worsening with age. Even if a mare is not to be bred, a Caslick's should be placed to protect her genital tract from her poor VC.

Pregnancy/Fertility/Breeding!!navigator!!

Surgery may be necessary to obtain a pregnancy.

Synonyms!!navigator!!

  • Windsucker
  • Windsucking

Abbreviations!!navigator!!

VC = vulvar conformation

Suggested Reading ⬆ ⬇

Colbern GT, Aanes WA, Stashak TS. Surgical management of perineal lacerations and recto-vestibular fistulae in the mare: a retrospective study of 47 cases. J Am Vet Med Assoc 1985;186:265–269.

Rothrock L, Ellerbrock R, Canisso IF. Outcomes on four mares undergoing perineal body reconstruction. Clin Theriogenol 2016;8(3):343.

Author(s) ⬆

Author: Carla L. Carleton

Consulting Editor: Carla L. Carleton

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