Uterine health in horses pertains to the condition and functionality of the uterus, an essential component of the mare's reproductive system. The uterus is responsible for supporting the development of the embryo and fetus during gestation. Various factors, such as infections, inflammation, and anatomical abnormalities, can impact uterine health, potentially affecting fertility and reproductive performance. Common conditions affecting the equine uterus include endometritis, pyometra, and uterine cysts. Assessment of uterine health often involves diagnostic tools like ultrasonography, endometrial biopsies, and cytological evaluations. This page compiles peer-reviewed research studies and scholarly articles that explore the anatomy, pathology, diagnostic techniques, and treatment options related to uterine health in horses.
Holtan DW, Squires EL, Lapin DR, Ginther OJ.Pony mares were bilaterally ovariectomized at different stages of pregnancy between Days 25 and 210. Abortion or fetal resorption occurred within 2 to 6 days after operations in all 14 mares ovariectomized between Days 25 and 45 and after an interval of 10 to 15 days in 9 of 20 other ovariectomized between 50 and 70 days. All 12 mares ovariectomized on either 140 or 210 days carried their foals to normal term. The termination of early pregnancy was preceded by a loss of uterine tone and of a palpable uterine bulge. The mean length of gestation in all mares in which pregnancy was not interrupte...
Steven DH, Jeffcott LB, Mallon KA, Ricketts SW, Rossdale PD, Samuel CA.Post-partum placentae and uterine biopsy samples from mares after normal and abnormal foalings are described. After normal delivery there is little damage to fetal or maternal tissues. The villous epitheliochorial palcenta separates cleanly at the maternal-fetal interface and the afterbirth consists almost exclusively of fetal tissue. Uterine involution is well advanced by the 3rd and 4th days post partum and the changes are usually complete by the oestrus 7--10 days after parturition. Placental separation and involution of the uterus appear to proceed normally in malpresented foals and in oth...
Gygax AP, Ganjam VK, Kenney RM.The surprisingly rapid rate of uterine involution detected is consistent with a high rate of conception as the first post-partum heat. Furthermore, many of the immediately post-partum features have attained the pregravid state by the end of the first post-partum oestrus and virtually all by the second post-partum oestrus. There was no specific cause detected for the higher rate of early embryonic death associated with conception at the foal heat.
Shin SJ, Lein DH, Aronson AL, Nusbaum SR.A total of 19 pathogenic bacterial species was isolated from uterine swabs of 498 out of 1539 mares over 4 years. The swabs were taken by 5 veterinary clinicians using 2 different techniques. Bacterial contamination during swabbing was minimized by scrupulous attention to cleansing of the external genitalia and the perineal area, and in the handling of the culture specimen. The most prevalent organisms isolated were beta-haemolytic streptococcus (39%), Escherichia coli (27%) and Klebsiella pneumoniae (7%). Interpretation of microbiological findings correlated well with clinical findings when n...
Zavy MT, Bazer FW, Sharp DC, Frank M, Thatcher WW.Prostaglandin F was measured by radioimmunoassay in uterine flushings of cycling mares on days 4, 8, 12, 14, 16, 18 and 20 post-ovulation. Prostaglandin F was significantly (P less than .05) affected by day of the estrous cycle and reached maximal levels on day 14. Least squares means for days 4, 8, 12, 14, 16, 18 and 20 were: .66, .81, 4.77, 14.31, 5.48, 3.68 and 2.97 ng/ml, respectively.
Digby NJ.Experimental studies of endometrial smears from 26 normal mares showed that after a period of sexual rest exceeding 7 days smears were generally free from inflammatory cells. Smears from 9 mares showing signs of persistent endometritis contained inflammatory cells in 91 per cent while bacterial culture was positive in only 45 per cent. Smears were also taken from 242 Thoroughbred mares as a routine procedure in 1977. It was concluded that endometrial cytology provides a better guide to uterine inflammation than bacteriology. The routine clinical use of endometrial cytology is recommended to ai...
Nitschelm D, Van der Horst CJ.It has been shown that stimulation of the uterus of mares by the daily taking of biopsies can result in the occurrence of oestrous symptoms. This is accompanied by some follicular growth and a progesterone content in the blood often higher than 1 ng/ml. The following observations suggest that this progesterone originates in the uterus and not in the ovaries: (1) no active corpora lutea appeared to be present in the ovaries after ovariectomy, (2) ovariectomized mares showed the same oestrous symptoms in similar experiments and even mating took place, (3) in the uterine biopsies the concentratio...
Kenney RM, Ganjam VK.Focal enlargements of the uterus are palpable through the rectal wall and have various aetiology. Aspects of their diagnosis, possible pathogenesis, significance and treatment are presented. Lymphatic lacunae appear to be quite common in older mares and may occasionally give rise to large endometrial cyst, but more frequently cause widespread change throughout the uterine horns. Three unusual ovarian abnormalities are presented, a large, oestrogen-producing granulosa cell tumour, an oestrogen-producing large follicle in a 4-month-old filly, and an ectopic progesterone-producing adrenal structu...
Engle CE, Foley CW, Witherspoon DM, Scarth RD, Goetsch DD.Three experiments were conducted on the metabolism of stallion sperm. In experiment 1, whole and washed sperm were incubated under aerobic and anaerobic enviroments and analyzed before and after controlled incubation for motility, pH, lactic acid, glucose, fructose, and O2 comsumption. In experiment 2, whole and washed sperm were incubated aerobically and anaerobically with and without uterine tubal fluids. Experiment 3 was the same as experiment 2, except added substrates of glucose and lactic acid were studied. The same examinations were made in experiments 2 and 3 as for experiment 1. Motil...
Stalheim OH, Gallagher JE, Deyoe BL.The luminal surface topography of bovine, equine, porcine, and caprine uterine tubes was studied by scanning electron microscopy. The main types of epithelial cells were secretory and ciliated. Both types were more active during estrus. Cilia were observed in both the infundibular and the ampular parts of the uterine tube, but ciliated cells were more numerous than secretory cells on the surface of the fimbriae. Sperm were observed in the ampulla of the uterine tube of the cow 2 hours after artificial insemination.
Martin RG, Penhale WJ, Williamson P.The influx of protein and polymorphonuclear leucocytes (PMN) into the uterine lumen was examined at different intervals after intrauterine infusion of fluids. The intrauterine infusion of both phosphate buffered saline (PBS) and a solution of lipopolysaccharide (LPS) derived from Escherichia coli resulted in a biphasic influx of protein in the uterine flushings peaking three and six hours after infusion. LPS infusion caused an additional influx of protein at 24 hours. The initial influx of protein preceded a biphasic influx of PMN which peaked six and 24 hours after both infusions. Uterine flu...
Tunón AM, Rodriguez-Martinez H, Haglund A, Albihn A, Magnusson U, Einarsson S.Cyclical accumulation of uterine fluid occurs during oestrus and is often seen in excessive volumes in mares considered susceptible to endometritis. Since the mechanisms behind the formation of free uterine fluid remain to be clarified, the fine structure of the secretory equine endometrium was studied in biopsies collect during videoendoscopy from 14 endometritis-free, 4-9-year-old mares during oestrus. A distinct oedema of the tunica mucosa was evident. The surface epithelium had both ciliated and nonciliated cells and, particularly at the uterine body, often presented intra-epithelial macro...
Turna Yilmaz O, Gunduz MC, Evkuran Dal G, Kurban I, Erzengin OM, Ucmak M.Doppler ultrasonography is a noninvasive technique which enables us to follow the physiologic and physiopathologic changes in blood flow in tissues. It is becoming an essential tool in veterinary medicine, especially in theriogenology. Twenty-seven Arabian mares were grouped by age ('young', 3-10 y, n=15; 'old', 19-23 y, n=12). The uterine arteries of the mares were examined using Doppler ultrasonography when an ovarian follicle ≥35mm was visible (Day -1). After these measurements, human chorionic gonadotropin (hCG; 2500IU) was administered to 14 mares selected randomly. One day later (Day 0...
Sertich PL, Watson ED.Twelve mares were allowed to foal naturally, after which they were monitored to study uterine involution. Starting on day 3 after parturition, the internal genital tract was examined per rectum manually and ultrasonographically every other day for changes in uterine characteristics and ovarian activity. By day 5, gravid and nongravid uterine horns were similar in size, and by day 7, uterine fluid was absent. On day 7 after parturition, endometrial biopsy samples were obtained for histologic evaluation, and uterine swab specimens were obtained for microbiologic culture. Uterine swab specimens f...
LeBlanc MM, Asbury AC, Lyle SK.Uterine response to inoculation with Streptococcus zooepidemicus organisms, 51Cr-labeled 15-microns microspheres, and charcoal was evaluated in 9 mares (4 resistant and 5 susceptible to endometritis) to determine mechanical and cellular clearance rates during the early postovulatory period. Mares were inoculated at estrus prior to ovulation during estrous cycles 1, 3, and 5. Uterine swab specimens for aerobic and anaerobic bacteriologic culture and serum for progesterone determination were obtained on postovulation day 3 during estrous cycle 1, on the day of ovulation during estrous cycle 3, a...
Jones DM, Fielden ED, Carr DH.Two intact and 2 ovariectomized mares aged 3-16 years had bipolar electrodes implanted in the myometrium to measure electromyographic (emg) activity during normal and exogenously simulated (with oestrogen and progesterone) cyclical activity (anoestrus, transition, oestrus and dioestrus). Oxytocin, cloprostenol, propantheline bromide and clenbuterol were administered during each cycle stage. In 1 mare, emg activity was recorded during natural breeding (4 times) and through the first 20 days of pregnancy. Simultaneous intrauterine pressure recordings (IUP) using an open tipped catheter system we...
Acland HM, Allen PZ, Kenney RM.Twenty-three of 24 mares were infected experimentally with contagious equine metritis organisms by intrauterine inoculation, and killed 2-116 days later. From mares killed within 14 days after infection the organism could be recovered from many sites in the uterus, and most sites in the cervix, a few sites in the vagina and oviduct and from one clitoral sinus. At this time the endometrial folds were swollen and there were 10-20 ml of fluid in the uterus. In mares killed after 14 days, the organism was recovered from the ovarian surface (1 mare), oviduct (4 mares), uterus (2 mares) and the clit...
Nitschelm D, Van der Horst CJ.It has been shown that stimulation of the uterus of mares by the daily taking of biopsies can result in the occurrence of oestrous symptoms. This is accompanied by some follicular growth and a progesterone content in the blood often higher than 1 ng/ml. The following observations suggest that this progesterone originates in the uterus and not in the ovaries: (1) no active corpora lutea appeared to be present in the ovaries after ovariectomy, (2) ovariectomized mares showed the same oestrous symptoms in similar experiments and even mating took place, (3) in the uterine biopsies the concentratio...
Günay Uçmak Z, Kurban I, Uçmak M.Endometritis is a major cause of infertility in mares. The aim of this study is to evaluate the preovulatory follicle (POF) vascularization (A mix, A red, A blue), POF diameter, POF wall thickness, and uterine diameters in mares with or without endometritis. Ten healthy mares and 10 mares with endometritis diagnosed by the combination of transrectal palpation, ultrasonographic examination, and cytology brush were enrolled in the study. Data of the groups obtained at 2 days before the ovulation (day -2) were compared with Student's t-test. Correlations of the parameters were determined by the ...
Gündüz MC, Kaşikçi G, Kaya HH.In this study, the effects of oxytocin and an analog of prostaglandin (cloprostenol) on the uterine involution and pregnancy rates were investigated. Mares received 3 ml of 0.9% NaCl in Group C (n=10), 30 IU/mare of oxytocin in Group O (n=10) and 250 microg/mare of cloprostenol in Group P (n=10) within 12h after parturition. The gravid uterine horn's cross-sectional diameter was measured by ultrasonography. The mean uterine diameters did not differ significantly between the treatment (O and P) and the control (C) groups (p>0.05). The difference between the postpartum ovulation periods (Grou...
Steven DH, Jeffcott LB, Mallon KA, Ricketts SW, Rossdale PD, Samuel CA.Post-partum placentae and uterine biopsy samples from mares after normal and abnormal foalings are described. After normal delivery there is little damage to fetal or maternal tissues. The villous epitheliochorial palcenta separates cleanly at the maternal-fetal interface and the afterbirth consists almost exclusively of fetal tissue. Uterine involution is well advanced by the 3rd and 4th days post partum and the changes are usually complete by the oestrus 7--10 days after parturition. Placental separation and involution of the uterus appear to proceed normally in malpresented foals and in oth...
Schatzmann U, Jossfck H, Stauffer JL, Goossens L.The effect of three alpha 2-agonistic sedatives, Detomidine (0.04 mg/kg), Romifidine (0.08 mg/kg) Xylazine (1.1 mg/kg) and placebo (NaCl), on intrauterine pressure was investigated with an intrauterine balloon model in four non-pregnant warmblood mares. Within 6.0 (+/- 2.2) min mean pressure increases of 9.80 (+/- 3.74), 6.88 (+/- 3.95) and 13.95 (+/- 5.19) mmHg were recorded for Detomidine, Romifidine and Xylazine, respectively. Placebo had no significant effect. The mean duration of pressure increase was 30.0 (+/- 5.10), 17.67 (+/- 9.87) and 19.50 (+/- 13.78) min for Detomidine, Romifidine a...
Kelley DE, Schnobrich MR, Gayer S, Scoggin C, Bradcamp E, Canisso IF.The objective of this study was to compare a commercially available leukocyte esterase strip test with endometrial cytology in diagnosing endometritis and establish a cutoff point, sensitivity, and specificity for the leukocyte esterase test (LET). Forty-six light breed mares presented for breeding management were enrolled in this study. Transrectal palpation and ultrasonography examinations were performed to determine when the mares were in estrus. Kalayjian endometrial swabs were used for culture, cytology, and the LET by using the cap to retrieve an endometrial scraping. Thirty-six mares ha...
LeBlanc M, Ward L, Tran T, Widders P.A direct ELISA was used to measure immunoglobulin (Ig) isotypes G, Gt, A, and M recognizing Streptococcus zooepidemicus epitopes in uterine lavage fluids collected during the early post ovulatory period. A S. zooepidemicus isolate, used as the plate antigen in this assay, was inoculated into the uteri of 8 mares (3 resistant and 5 susceptible to endometritis) at oestrus prior to ovulation during Oestrous Cycles 1, 3 and 5. Resistant mares aged 2-5 years were nulliparous, with clinically normal reproductive tracts as determined by physical examination, bacteriological culture of the uterus, and...
Pycock JF, Allen WE.The uteri of normal pony mares in oestrus were infected experimentally with Streptococcus zooepidemicus. Uterine contents were collected 30, 60, 120 or 240 minutes later and were tested for their chemotactic effect on equine-neutrophils both with a morphological assay based on neutrophil shape changes and with a modified Boyden chamber technique. By 30 minutes after infection the uterine contents were markedly chemotactic for isolated peripheral neutrophils and remained so at the 240-minute collection. Uterine contents from uninfected mares had minimal chemotactic properties. These results cou...
Katila T, Lock TF, Ely RW, Smith AR.The study was designed to determine differences between normal mares and mares with endometrial pathology in the inflammatory response after bacterial challenge. Six normal mares (biopsy category I) and 4 mares with pathological endometrial changes (biopsy category II) were given an intrauterine infusion of β-hemolytic streptococci on the second day of estrus. All mares had a similar kind of inflammatory response after the bacterial inoculation as assessed by rectal and vaginal examinations. There were no significant differences in the amount of discharge, uterine tone, uterine size and cervi...
Walesby HA, Venugopal CS, Hosgood G, Eades SC, Moore RM.To characterize the in vitro response of circular and longitudinal myometrial layers of the uterine horn (CMLH and LMLH, respectively) of horses to endothelin (ET)-1 by use of specific ETA (BQ-123) and ETB (IRL-1038) receptor antagonists. Methods: Uteruses from 10 nongravid mares in anestrus. Methods: Muscle strips from the CMLH and LMLH were suspended in tissue baths and connected to force-displacement transducers interfaced with a polygraph. Strips were incubated for 45-minute intervals with no antagonist (control specimens), and 3 concentrations (10(-9), 10(-7), and 10(-5)M) of BQ-123, IRL-...
Niikura T, Tsogtgerel M, Niikura C, Wada H, Kanzawa S, Fujiwara T, Nambo Y.The objective of this study was to examine the effect of prostaglandin F2α (dinoprost) and oxytocin administration on uterine polymorphonuclear neutrophil counts in the Japanese heavy draft mare. To compare polymorphonuclear neutrophil (PMN) counts in the endometrium, a total of 162 samples were collected from 54 estruses of 47 mares (before ovulation, day 0, and day 2) using a double-guarded cytology brush. Dinoprost (PG; 5 mg) was administered intramuscularly (i.m.) only once, on day 0, whereas oxytocin (OT; 20 U i.m.) was administered three times at 12-hr intervals starting on day 0. The p...
Johnson JU, Oxender WD, Berkhoff HA.Effect of estrogen (E2) and progesterone (P4) on uterine antibacterial activity and immunoglobulin concentrations in mares was studied. In 2 in vitro experiments, 6 mixed-breed mares were ovariectomized, and uterine fluid and blood serum were analyzed. Antibacterial assay methods were used to determine inhibitory effects on Streptococcus zooepidemicus of uterine fluid samples collected on days 3, 5, and 8, and serum obtained on day 8 of treatment. Single radial immunodiffusion methods were used to quantify amounts of IgA and IgG in uterine fluid and serum on days 3, 5, 8, and 14 of treatment. ...
LeBlanc M, Neuwirth L, Mauragis D, Klapstein E, Tran T.The effects of oxytocin on the percentage of technetium 99m albumin colloid (99mTc-microAA), cleared from the uterine lumen was measured in 13 mares. Scintigraphy was performed during 4 consecutive oestrous cycles, on Day 3 of oestrus during Cycles one and 3 and 48 h after ovulation during Cycles 2 and 4. Oxytocin (20 iu) was given i.v. after the initial scintigraphy image during Cycles 3 and 4. Seven multiparous mares (Group 1) were classified as 'susceptible' and 6 mares (2 nulliparous and 4 multiparous; Group 2) were classified as 'resistant' to endometritis. All mares cleared > 90% of 99mT...
Kolm G, Gemeiner M, Deichsel K, Budik S, Aurich J, Aurich C.The failure of clearance mechanisms in the mare's uterus results in persistent inflammation and is considered a major cause of subfertility. Eighteen mares, of which three were susceptible to endometritis and four had been ovariectomised, underwent charcoal clearance testing to evaluate their clearance mechanisms. This consisted of installing 500 mg of charcoal (particle size 4 to 90 microm) added to 50 ml of phosphate-buffered saline (PBS) into the uterus. Forty-eight hours later the uterus was flushed out with 0.0012 per cent methylene blue in 50 ml of PBS for determination of the diluting f...
Ball BA, Dobrinski I, Fagnan MS, Thomas PG.To examine glycoconjugates in the isthmic and ampullar regions of the uterine tube (oviduct) of horses during estrus, diestrus, and pregnancy. Methods: Oviductal samples from 17 mares. Methods: Oviducts were collected during estrus (n = 3), diestrus (n = 3), or pregnancy (n = 3), embedded, and snap frozen in liquid nitrogen. Frozen sections (5 to 6 microns in thickness) were stained with 100 micrograms/ml of fluorescein-isothiocyanate-conjugated lectin (30 min at 38.5 C) and were evaluated by use of epifluorescence microscopy and video image analysis. Specificity of lectins was established by ...
Buczkowska J, Kozdrowski R, Nowak M, Sikora M.Endometrial biopsy score is an accepted marker of uterine health and predicted fertility, and it has been suggested that endometrial alternations are correlated with susceptibility to persistent infectious endometritis. The objective of this study was to investigate associations of endometrial biopsy score with: 1) presence of polymorphonuclear cells (PMNs) in the epithelium and stratum compactum in histopathology; 2) presence of PMNs in cytology and 3) presence of infection in microbiology. Methods: The material for examination was collected from 69 mares suspected for subclinical endometriti...
Ginther OJ.Traveling of the fetal-amniotic unit throughout the uterus ceases on ∼ Day 180 followed by closure of each uterine horn. By mean Day 240, the fetus and nearly all of the pool of allantoic fluid are confined to the uterine body. Intrauterine fetal-location changes end, but in-place activity of limbs, head, and body and changes in fetal recumbency and presentation continue, sometimes vigorously. Preference for cranial presentation (fetal sternum toward maternal cervix) has been hypothesized to be stimulated by ∼ 40° incline of uterine body toward the cervix. The uterine body expands forward...
Weitkamp LR, Kenney RM, Bailey E, MacCluer JW, Brown JS, Blanchard TL, Sertich PL, Love CC, Hunt PR.Histological features of the endometrium, as assessed in biopsy samples, were related to Standardbred mare genotypes for transferrin, esterase (as a control) and equine leucocyte antigens (ELA). Pathological changes were found more frequently in each successively older age group of mares. Among mares aged 6-19 years, there were significant pathologic changes on first examination following an infertile breeding season for 46 of 90 (51%) of transferrin homozygotes and 50 of 146 (34%) of transferrin heterozygotes. The difference between the two groups was significant for the total data (chi 1(2) ...
Hawkes M, Richard A, Oldfield C, Toothaker A, Stokes M, Causey R.Postbreeding bacterial uterine infections inflict major losses on the equine industry. Microcurrents propelled by ciliated cells between the folds of the uterus and cervix have been proposed as a means by which contaminants are expelled. Previous data have shown possible ciliary microcurrents propelling carbon particles, occasionally rotating, through cervical folds. However, adherence to the epithelium may have interfered with movement of carbon in these studies. Therefore, we tested potentially nonadherent substances to reveal ciliary microcurrents on the equine cervix under high magnificati...
Miragaya MH, Woods GL, Losinno L.The occurrence of uterine and oviductal inflammation, and fertilisation rates, were measured on Day 3 post ovulation in inseminated mares that had either exhibited intrauterine lumenal fluid during a previous dioestrus (Experiment 1) or had acute endometritis induced by intrauterine infusion of 1% glycogen (Experiment 2). Endometritis was assessed by uterine cytology and histology whereas oviductal inflammation was measured histologically. Fertilisation rates were calculated from the percentage of cleaved ova recovered by retrograde flushing of the oviducts. Mares with or without pre-existing ...
Griffin PG, Ginther OJ.Fetal activity and mobility and changes in diameter of the allantoic fluid compartment in the uterine horns were studied in mares between days 69 and 81 of pregnancy by use of transrectal ultrasonography (n = 12) and transcervical videoendoscopy (n = 8). The insertion tube of the videoendoscope was positioned within the allantoic sac to permit viewing of the fetus and entrance to each uterine horn. Each uterine horn was divided ultrasonographically into 3 segments of equal length, and the horns were designated on the basis of side of umbilical attachment (cord vs noncord horns). The diameter o...
Satoh M, Higuchi T, Inoue S, Gotoh T, Murase H, Nambo Y.This is a retrospective study of uterine torsion (UT) in seven mares. In two cases, serum progesterone and estradiol concentrations were also investigated. The mare and foal/fetus survival rate was 57% (4/7). Four cases presented with clockwise torsion, and two cases presented with counterclockwise torsion. The direction was undetermined in one case. The degree of torsion varied. Correction of torsion was performed by ventral midline celiotomy in all cases. In the two cases with measured hormone levels, elevated levels of P were decreased through medication. All mares discharged from the hospi...
Madej A, Kindahl H, Nydahl C, Edqvist LE, Stewart DR.Two mares received PGF-2 alpha twice daily until abortion and 2 mares received a combined treatment with oestradiol benzoate and oxytocin. The mares were about 150 days pregnant. The PG-treated animals aborted after 37 and 61 h, respectively, and the fetuses were expelled in intact fetal membranes. The other 2 mares aborted 13 and 27 h after the first oxytocin injection, respectively, and showed strong uterine contractions and expelled the fetuses in disrupted fetal membranes. Concentrations of 15-ketodihydro-PGF-2 alpha increased both after PG and oxytocin injections and in association with t...
