HOW TO TREAT THE SUB-FERTILE MARE


but they provide an endometrial biopsy score, which is an accepted marker of uterine health and pre- dicted fertility.10 More than one sample from dif- ferent areas of the uterus can be obtained to verify the repeatability of degenerative changes.11 The endometrium is classified according to the presence of inflammation (type and severity), endometrial gland density, periglandular fibrosis and gland nest- ing, and cystic glandular distension.10,12 As the number and severity of pathologies increase so does the category classification, whereas the potential of carrying a foal to term decreases.13 Category I has little or no pathologic changes with an 80–90% foaling rate. Category IIA has either slight-to- moderate diffuse superficial inflammatory changes, infrequent fibrotic changes involving individual glands (less than three layers of fibrosis), mild fi- brotic nesting, or lymphatic lacunae. Mares with a Category IIA endometrium would be expected to carry a foal to term 50–80% of the time. Category IIB is any mare barren for 2 years or more, or with widespread diffuse, moderately severe inflamma- tion, or more extensive fibrotic changes of individual glands with increased gland nesting. These changes lead to a 10–50% expected term foaling rate. Category III has widespread, diffuse, severe inflammation with extensive fibrosis and nesting. Unfortunately, the Kenny-Doig classification system described above does not take into account the amount of edema, lymphatic stasis, mitotic figures within the endometrial glands, or endometrial an- giopathies that may be present within the endometrium.12–14


2. Materials and Methods


Most subfertile mares have a pendulous uterus that sits cranially and ventrally in the caudal abdomen due to stretching of the broad ligaments with in- creased age and parity, decreased uterine contrac- tility, and poor perineal conformation.15 These factors, combined with gravity, cause intraluminal fluid, inflammatory cells, bacteria, mucus, and de- bris to reside in the most dependent part of the uterus, usually the base of the uterine horns. An endometrial sample obtained by a guarded swab or brush would only reach an area of the uterine body just cranial to the cervix due to the swab’s length. Therefore, in the author’s opinion, to obtain a rep- resentative sample of the uterine environment in these problem mares, culture and cytology should be performed with a low-volume lavage or endometrial biopsy.


Low-volume lavage is usually performed during


estrus as described by LeBlanc by infusing the uterus with 60–150 mL of sterile saline or lactated Ringer’s solution.7 The mare’s perineal region is cleansed, especially between the vulvar lips. A sterile closed system is used with a catheter passed per vaginum into the uterus and up into a uterine horn by an examiner whose arm is covered by a sterile sleeve. Commercially obtained uterine la-


vage tubes or medical grade silicone tubing can be used.7 Sterile saline is infused into the uterus by attaching either a 60-mL catheter-tip syringe con- taining 60 mL of saline or a 150-mL bag of sterile saline to the end of the catheter.7 The uterus is massaged by transrectal palpation to distribute the fluid throughout the lumen, and subsequently, the effluent is recovered back into the attached sterile bag.7 If the mare is in heat and the fluid is trapped in the edematous endometrial folds, the administra- tion of 10 IU oxytocin IV to stimulate uterine drainage through myometrial contractions is recom- mended.12 However, when a small volume is placed into a pendulous large atonic uterus it can be very difficult to retrieve, especially if it has dissi- pated into the horns and extensive transrectal ma- nipulation can lead to contamination and increased procedure duration, which, in a field situation may not be optimal. The author therefore performs a low volume lavage using1Lof sterile saline or lactated Ringer’s solution. A sterile flush catheter such as bivonaa with a Christmas tree, and an ex- tension set is connected to a sterile liter bottle of fluids. The catheter system is primed with fluid and placed into the uterus shielding the tip of the flush catheter with a sterile gloved hand as it enters the vagina, cervix, and uterus. The bottle of warmed fluids is inverted upside down and gravity allows influx into the uterus. The fluid disperses throughout the uterus by gravity rapidly. Removal of the fluid occurs with lowering of the bottle toward the ground, thus minimizing contamination. The sterile top is replaced and sealed with tape for de- livery to the laboratory. The recovered effluent is evaluated for cloudiness and the amount of mucus. When using the smaller volume (60–150 mL) to obtain the precipitate, the sample is allowed to set- tle for at least 30–60 minutes or centrifuged at 400 g for 10 minutes and all but 5 mL of the supernatant is discarded. The pellet is then sam- pled with a sterile cotton swab for culture and an- other for cytology. When1Lis used, the laboratory at Hagyard Equine Medical Institute allows the bot- tle to sit for 1 hour. After the lavage effluent has settled, a 10-mL pipet is inserted to the bottom of bottle slowly and 10mLof the sediment is drawn up. Five mL lavage sediment is placed in two 12  75-mm test tubes. The tubes are centrifuged at 400  g for 1 min. The supernatant is discarded, and the pellet is resuspended in the small amount of fluid remaining in the bottom of the tube. One sample is used for culture and the other for cytology. Two cytology samples are made by rolling the cells onto a glass microscope slide. One is then Wright stained and the other Gram stained. A swab of the cellular material from the other tube is streaked on blood and MacConkey agara and incubated for 48 hours. Samples must be processed for culture within 8 hours because saline does not preserve bacteria.


AAEP PROCEEDINGS  Vol. 62  2016 165


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