Perineal Conformation

Perineal Conformation



Basic Information image



Definition


The perineum is the body wall surrounding the pelvic outlet, anal canal, and urogenital passage. The vulva is composed of the labia and clitoris. Normal conformation is required for normal reproductive health. The vulvar lips should meet evenly to form a tight mucosal seal, and two thirds of the vulvar cleft should lie below the pelvic floor. The vulvar lips should be vertical with no more than a 10-degree slope from cranial to caudal.



Synonym(S)


Vulvar anatomy, angle of declination (slope to vulvar lips)



Epidemiology



Species, Age, Sex




• All Equids used for breeding should be assessed for normal perineal conformation.


• An increase in age results in elongation of the vulvar opening and an increase in slope caused by ligament and muscle relaxation.


• An increase in parity may result in stretching and trauma to the reproductive structures.



Genetics and Breed Predisposition




• Thoroughbreds and American Saddlebreds have an increased likelihood to have more angulation to the vulva.


• Quarter Horses and Standardbreds are more likely to have vertical orientation to the vulva.



Risk Factors




• Repeated vulvoplasty results in vulvar trauma and scarring, often requiring vulvoplasty in subsequent breeding seasons.


• Dystocia or natural cover leading to perineal trauma.


• Trauma to the perineum may result in permanent vulvar pathology.


• Underweight resulting in decreased intrapelvic fat.


• Flat croup or elevated tail results in more vulvar angulation.


• Neoplasia altering the apposition of the vulvar labia.



Geography and Seasonality




• Mares under the influence of estrogen will have decreased vulvar tone.


• Mares under the influence of progesterone will have increased vulvar tone.



Associated Conditions and Disorders


Poor perineal conformation may lead to subfertility or infertility associated with pneumovagina, urovagina, fecal contamination with subsequent endometritis, cervicitis, or placentitis. The most common neoplasias of the external genitalia are squamous cell carcinoma, melanoma, and papillomas. Trauma may occur during parturition, resulting in various degrees of perineal lacerations.



Clinical Presentation



History, Chief Complaint




• Abnormal conformation


image Unsuccessful breeding attempts

image Vulvar discharge

image Vulvar air aspiration during riding or when working

image Discharge present on base of tail

image Pre- or postbreeding endometritis

image Early embryonic death

• Neoplasia


image Vulvar discharge

image Swollen vulva

image Perineal or vulvar mass(es)

image Ulcerations on vulva


Physical Exam Findings




• More than one-third of the vulvar cleft dorsal to the pelvic floor


• Greater than 10-degree slope of the vulvar lips from cranial to caudal


• Urine pooling on vaginal speculum examination


• Positive windsucker test result: Aspiration of air into the vagina upon separation of the vulvar lips


• Vulvar discharge present on vulvar lips or ventral base of the tail


• Disruption of normal vulvar mucosal seal


• Caslick’s index greater than 150: Taken by multiplying the length (in centimeters) of the vulvar opening above the pelvic floor by the angle of declination of the vulva


• Presence of air or fluid on ultrasonographic examination of the uterus

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Jul 24, 2016 | Posted by in SMALL ANIMAL | Comments Off on Perineal Conformation

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