IN-DEPTH INTERACTIVE: REPRODUCTIVE DISORDERS – PATHOLOGY TO TREATMENT


(R. Ferris, unpublished data, 2014) showed that S. equi subsp. zooepidemicus obtained from equine uterine swabs also produced biofilms. Ongoing work is examining effective treatments against biofilm producing bacteria in the equine uterus.


Diagnostic Tools for Endometritis


The evaluation process always starts with an accu- rate history of both general and reproductive health, a full physical examination, and a thorough exami- nation of both the external and internal genitalia. Examination tools that are commonly used include evaluation of the perineal area, transrectal palpa- tion and ultrasonography of the reproductive tract, sampling for uterine culture, cytology, endometrial biopsy, and vaginal examination. Results from these tests help identify obvious, and often correct- able, problems. Additional tests such as low-vol- ume uterine lavage for cytology and culture, hysteroscopy, and karyotyping are sometimes nec- essary to gain needed information.


General Physical and Perineal Examination


Overall, good physical health and conformation are important for reproductive health in mares. Al- though perineal anatomy is often the focus of atten- tion when evaluating a mare for fertility, it is important to consider the impact overall body con- dition has on perineal anatomy. Underweight mares frequently have a pelvic tilt that results in a dependent uterus and sinking of the anal sphincter, both of which indicate risk factors for uterine con- tamination. A first step toward good reproductive health is good body condition, which can help correct perineal defects. Vulvar anatomy is a critical first-line defense against uterine contamination. Poor perineal con- formation predisposes the mare to “wind sucking,” fecal contamination, and pooling of urine in the va- gina. The long axis of the vulva should be vertical, with no more than a 10° angulation. Most of the vulva should be ventral to the pelvic brim. When 2 fingers are placed on the pelvic ischium, no more than 2.5 cm of the vulva should be dorsal to the pelvic floor. The vulvar lips should not have obvi- ous irregularities, and apposition should be good. When the vulvar lips are gently parted, no obvious influx of air should be heard. The vestibule-vaginal seal can be evaluated through the parted vulvar lips and should be intact.


Transrectal Ultrasound Examination


Ultrasound examination is an important and useful component for evaluating reproductive health in mares. Intraluminal uterine fluid around the time of breeding and ovulation has an established rela- tionship to reduced pregnancy rates in cycling and postpartum mares.14–16 Postmating-induced endo- metritis is the most common cause of uterine fluid accumulation during the periovulatory period of mares.4 Mares with delayed uterine clearance of-


278 2015  Vol. 61  AAEP PROCEEDINGS


ten have defects in intrinsic myometrial contractil- ity5 and drainage through the lymphatics that is evidenced by lymphatic stasis.6 The conditions fre- quently manifest themselves as intraluminal fluid accumulation and abnormal uterine edema patterns during estrus.7 Specifically, these mares often have an unusually large amount of uterine edema starting early in the estrus period and persisting after ovulation. Interestingly, mares with bacte- rial endometritis do not consistently develop in- traluminal fluid. Recent studies8,9 reported that mares that had uterine infections caused by E. coli were less likely to have intrauterine fluid accumu- lation identified by ultrasound and less evidence of cytologic inflammation. Mares with uterine infec- tions caused by -hemolytic Streptococcus, K. pneu- moniae, Enterobacter cloacae, or yeast had a higher incidence of ultrasonographically detectable uterine fluid. These findings can be useful when determin- ing the need for additional diagnostic tests.


Uterine Culture and Cytology


Culture and cytology should be performed to eval- uate for potential endometritis. Uterine culture and cytology can be obtained from either a double- guarded swab, cytology brush, endometrial biopsy, or low-volume uterine lavage. Culture and cytol- ogy should be performed together because both tests have a high prevalence of false negatives when used alone. Because the vagina is not a sterile environment, false-positive culture results are common as a result of contamination from the perineum or the vagina. Conversely, aerobic cul- ture may fail to diagnose fungal or yeast infec- tions, which are more easily detected upon cytology. In general, any bacterial growth in con- junction with neutrophils upon cytology is consid- ered diagnostic for uterine infection. In addition, pure growth of a single organism, particularly those that commonly contribute to endometritis, could arguably be considered diagnostic for infec- tion even in the absence of positive cytology. Commonly described reproductive pathogens in the mare include S. equi subsp. zooepidemicus, E. coli, K. pneumoniae, and P. aeruginosa. Historically, the presence of more than two neu- trophils per high-powered field is diagnostic for en- dometritis.17 A recent study18 examined the cytologic sampling methodology (cytology brush vs. endometrial biopsy), interpretation of results, and correlation to endometritis in mares. Conclusions from this study were 2-fold: first, endometritis di- agnosis was more accurate when assessing the per- centage of polymorphonuclear leukocytes (PMNs) in the total cells evaluated (2% PMNs in 300 cells counted) versus the number of PMNs per high- powered field (defined as onePMNper high-powered field); second, endometrial biopsy offered no advan- tage over cytology brush for diagnosing endometri- tis. These interesting data may help lead to more accurate endometritis diagnoses using traditional


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