A clinical approach to determine false positive findings of clinical endometritis by vaginoscopy by the use of uterine bacteriology and cytology in dairy cows

Innate immunity and inflammation of the bovine female reproductive tract in health and disease

Mammalian reproductive physiology and the development of viviparity co-evolved with inflammation and immunity over millennia. Many inflammatory mediators contribute to paracrine and endocrine signalling, and the maintenance of tissue homeostasis in the female reproductive tract. However, inflammation is also a feature of microbial infections of the reproductive tract. Bacteria and viruses commonly cause endometritis, perturb ovarian follicle development and suppress the endocrine activity of the hypothalamus and pituitary in cattle. Innate immunity is an evolutionary ancient system that orchestrates host cell inflammatory responses aimed at eliminating pathogens and repairing damaged tissue. Pattern recognition receptors on host cells bind pathogen-associated molecular patterns and damage-associated molecular patterns, leading to the activation of intracellular MAPK and NFκB signalling pathways and the release of inflammatory mediators. Inflammatory mediators typically include the interleukin cytokines IL1β and IL6, chemokines such as IL8, interferons and prostaglandins. This review outlines the mechanisms of inflammation and innate immunity in the bovine female reproductive tract during health and disease condition.

Invited review: Systematic review of diagnostic tests for reproductive-tract infection and inflammation in dairy cows

The objective of this study was to conduct a systematic and critical appraisal of the quality of previous publications and describe diagnostic methods, diagnostic criteria and definitions, repeatability, and agreement among methods for diagnosis of vaginitis, cervicitis, endometritis, salpingitis, and oophoritis in dairy cows. Publications (n=1,600) that included the words "dairy," "cows," and at least one disease of interest were located with online search engines. In total, 51 papers were selected for comprehensive review by pairs of the authors. Only 61% (n=31) of the 51 reviewed papers provided a definition or citation for the disease or diagnostic methods studied, and only 49% (n=25) of the papers provided the data or a citation to support the test cut point used for diagnosing disease. Furthermore, a large proportion of the papers did not provide sufficient detail to allow critical assessment of the quality of design or reporting. Of 11 described diagnostic methods, only one complete methodology, i.e., vaginoscopy, was assessed for both within- and between-operator repeatability (κ=0.55-0.60 and 0.44, respectively). In the absence of a gold standard, comparisons between different tests have been undertaken. Agreement between the various diagnostic methods is at a low level. These discrepancies may indicate that these diagnostic methods assess different aspects of reproductive health and underline the importance of tying diagnostic criteria to objective measures of reproductive performance. Those studies that used a reproductive outcome to select cut points and tests have the greatest clinical utility. This approach has demonstrated, for example, that presence of (muco)purulent discharge in the vagina and an increased proportion of leukocytes in cytological preparations following uterine lavage or cytobrush sampling are associated with poorer reproductive outcomes. The lack of validated, consistent definitions and outcome variables makes comparisons of the different tests difficult. The quality of design and reporting in future publications could be improved by using checklists as a guideline. Further high-quality research based on published standards to improve study design and reporting should improve cow-side diagnostic tests. Specifically, more data on intra- and interobserver agreement are needed to evaluate test variability. Also, more studies are necessary to determine optimal cut points and time postpartum of examination.

Differential endometrial cell sensitivity to a cholesterol-dependent cytolysin links Trueperella pyogenes to uterine disease in cattle

Purulent disease of the uterus develops in 40% of dairy cows after parturition, when the epithelium of the endometrium is disrupted to expose the underlying stroma to bacteria. The severity of endometrial pathology is associated with isolation of Trueperella pyogenes. In the present study, T. pyogenes alone caused uterine disease when infused into the uterus of cattle where the endometrial epithelium was disrupted. The bacterium secretes a cholesterol-dependent cytolysin, pyolysin (PLO), and the plo gene was identical and the plo gene promoter was highly similar amongst 12 clinical isolates of T. pyogenes. Bacteria-free filtrates of the T. pyogenes cultures caused hemolysis and endometrial cytolysis, and PLO was the main cytolytic agent, because addition of anti-PLO antibody prevented cytolysis. Similarly, a plo-deletion T. pyogenes mutant did not cause hemolysis or endometrial cytolysis. Endometrial stromal cells were notably more sensitive to PLO-mediated cytolysis than epithelial or immune cells. Stromal cells also contained more cholesterol than epithelial cells, and reducing stromal cell cholesterol content using cyclodextrins protected against PLO. Although T. pyogenes or plo-deletion T. pyogenes stimulated accumulation of inflammatory mediators, such as IL-1beta, IL-6, and IL-8, from endometrium, PLO did not stimulate inflammatory responses by endometrial or hematopoietic cells, or in vitro organ cultures of endometrium. The marked sensitivity of stromal cells to PLO-mediated cytolysis provides an explanation for how T. pyogenes acts as an opportunistic pathogen to cause pathology of the endometrium once the protective epithelium is lost after parturition.

Endometrial cytology, biopsy, and bacteriology for the diagnosis of subclinical endometritis in grazing dairy cows

The objectives of this study were to assess the agreement between endometrial cytology and uterine biopsy for the diagnosis of subclinical endometritis (SEND) in grazing dairy cows, the interobserver agreement of the biopsy's readings, and the bacterial population isolated from the uterus of cows having SEND. In experiment 1, lactating Holstein cows (n=44) 31 to 59 d in milk (DIM) at sampling were enrolled. Clinical endometritis was diagnosed by direct evaluation of vaginal discharge and SEND by endometrial cytology evaluation. Two hundred cells per smear were counted to determine the percentage of polymorphonuclear neutrophilic leukocytes (PMNL). Cut-off values used were ≥8% PMNL at ≤33 DIM, ≥6% PMNL at 34 to 47 DIM, and ≥4% PMNL at ≥48 DIM. Biopsies were assessed blindly by 2 observers who categorized them into 4 groups according to their inflammatory changes: none, minimal, moderate, and severe inflammatory changes. Data were analyzed using the kappa coefficient and logistic regression. In experiment 2, lactating Holstein cows (n=60) 21 to 62 DIM were enrolled. Clinical endometritis and SEND were diagnosed as previously described. Samples were cultured for aerobic and anaerobic bacteria by routine methods of bacteriological testing. Data were analyzed with logistic regression. In experiment 1, little agreement was observed between cytology and biopsy outputs (kappa=0.151), and strong agreement between the 2 operators (kappa=0.854). The likelihood of having a normal biopsy (no inflammatory change) was greater for healthy cows than for those having SEND (odds ratio=13.145). The probability for getting normal uterine tissue decreased 2.1% for every increasing percentage point in PMNL. In experiment 2, no bacteria were isolated from cows with SEND, coagulase-negative staphylococci were commonly isolated from healthy cows, and Trueperella pyogenes was frequently isolated from cows with clinical endometritis. The likelihood of isolating T. pyogenes from uterine samples increased with the percentage of PMNL (odds ratio=1.100). In conclusion, biopsy showed low agreement with cytology for the diagnosis of SEND. Nevertheless, fertility trials using uterine biopsies to predict pregnancy outcomes are needed to determine its diagnostic usefulness. Finally, bacteriology would not be recommended as a diagnostic tool because no bacteria were isolated from cows with SEND.

Strategies for the treatment of dairy cows at high risk for postpartum metritis and for the treatment of clinical endometritis in Argentina

The objectives of this study were to evaluate the efficacy of (1) administering ceftiofur hydrochloride in dairy cows with calving-related disorders to prevent metritis and (2) a combination of GnRH and PGF2α for the treatment of clinical endometritis, under Argentinean dairy farming conditions. Cows at high risk (HRC) for metritis (dystocia, RFM >12 h postpartum, hypocalcaemia, twins, or stillbirth) were randomly assigned to receive either 1.1 mg/Kg of ceftiofur hydrochloride on three consecutive days (HRC treated group HRCT, n = 110) or remained untreated (HRC control group HRCC, n = 126). Cows with low risk (LRC, no calving-related disorders, n = 868) did not receive any treatment (LRC group, n = 868). All cows were examined for metritis between days 4 and 10 and for clinical endometritis between 24 and 30 days postpartum. The body condition score (BCS) was recorded at both examinations. Cows with endometritis at days 24 to 30 postpartum received either 1.5 mg of D-cloprostenol (PGF; n = 129) or 100 μg of GnRH followed by D-cloprostenol after 7 days (GnRH+PGF, n = 119). There was no overall effect of treatment on the incidence of metritis or on time to pregnancy. Treatment, however, reduced the incidence of metritis in cows with high BCS (HRCT = 24.0 %, HRCC = 38.5 %) but had no effect in cows with low BCS (HRCT = 38.7 %, HRCC = 37.5 %). The proportion of pregnant cows by days in milk was greater (P < 0.01) in LRC group compared with that of the HRCT and HRCC groups. No significant differences were found between groups PG and PG+GNRH. GnRH+PGF treatment, however, tended (P = 0.06) to increase pregnancy rate in cows with a moderate loss of BCS (76.5 vs 65.2 %) but tended to reduce pregnancy rate (54.5 vs 76.0 %) in cows with a more pronounced loss in BCS (>0.75 points).

Relationship between bacteriological findings in the second and fourth weeks postpartum and uterine infection in dairy cows considering bacteriological results

The uterine lumen in early postpartum dairy cows is contaminated with different bacteria. The most relevant uterine pathogens are Escherichia coli and Trueperella pyogenes. Prevalence of α-hemolytic streptococci and coagulase-negative staphylococci (CNS) is also high; however, these pathogens are considered opportunistic. The overall objective of this study was to investigate effects of the intrauterine presence of E. coli, T. pyogenes, α-hemolytic streptococci, or CNS at 10±1 d in milk (DIM) on the type of bacteria 2 wk later and their influence on uterine infections and subsequent reproductive performance. Furthermore, we set out to quantify 2 relevant methodological factors (i.e., laboratory and sampling instrument). Bacteriological samples were collected at 10±1 and 24±1 DIM from the uterine lumen using a cytobrush (CB). Vaginal mucus was classified by vaginoscopy. In a subsample, bacteriological results of 3 different laboratories and of CB and cotton swabs (CS) were compared. Samples of uterine discharge were collected at 10±1 DIM and bacteriological samples were taken using CB and CS. Bacteria were identified and bacterial growth quantified on a 4-point scale. Animals infected with E. coli or T. pyogenes at 10±1 DIM had a higher risk for an infection with the same bacterial species at 24±1 DIM [E. coli relative risk (RR)=3.7 and T. pyogenes RR=2.9]. Moreover, the risk of being diagnosed with abnormal vaginal discharge at 24±1 DIM increased in cows with E. coli (RR=1.7) or T. pyogenes (RR=1.7) at 10±1 DIM. Uterine infection with α-hemolytic streptococci or CNS did not increase the risk of an infection with T. pyogenes or E. coli or abnormal vaginal discharge 2 wk later. Cows with E. coli at 10±1 DIM or T. pyogenes at 24±1 DIM had greater days to first artificial insemination than cows positive for the 3 remaining bacterial species. Cows with T. pyogenes at 10±1 DIM had more days to pregnancy and more cows were culled when positive for E. coli at 10±1 DIM. Agreement of bacteriological results of 3 different laboratories were significant for laboratory A + B and A + C for the CB and CS. The highest agreement considering the bacterial species was for E. coli. All results for laboratory A + B and A + C for the CB and CS were significant. The results generated from samples collected with CB agreed nicely with those from CS from each laboratory (laboratory A: 250/272; laboratory B: 264/272; laboratory C: 253/272).

A novel diagnostic technique to determine uterine health of Holstein cows at 35 days postpartum

The objectives were (1) to evaluate the association of uterine lavage sample optical density (ULSOD) with uterine health, and (2) to estimate and evaluate a threshold value that will maximize the accuracy of ULSOD as a diagnostic tool for clinical endometritis. The study enrolled 1,742 cows from 3 dairy farms located near Ithaca, New York. The samples were collected at 35 ± 3 d in milk (DIM) by using low-volume uterine lavage. Cows with a purulent or mucopurulent secretion in the sample were diagnosed with clinical endometritis, whereas a subgroup of all studied cows was examined for cytological evidence of inflammation by endometrial cytology. Data for ULSOD measured at different wavelengths (200, 352, 620, 790, 860, and 960 nm) were available for 554 cows; all 1,742 cows had data for ULSOD measured at 620 nm (ULSOD(620)). Incidences of clinical endometritis, metritis, and retained placenta were 10, 15.2, and 5.6%, respectively. The ULSOD(620) was associated with clinical endometritis. Receiver operating characteristic (ROC) analysis of the accuracy of optical density in the detection of clinical endometritis was conducted for ULSOD measured at different wavelengths; ULSOD(620) was selected for further analysis because it presented the best ROC curve to detect clinical endometritis. The recommended threshold for ULSOD(620) ROC was 0.058, where the sensitivity and specificity were 76.3 and 78.3%, respectively. The ROC analysis of the accuracy of optical density in the detection of endometritis defined as a percentage of neutrophils in the uterine lavage samples higher than 18% was conducted for ULSOD(620). The recommended threshold was 0.059, where the sensitivity and specificity were 100 and 82.2%, respectively. Cows with ULSOD(620) ≤ 0.058 were 1.21 times more likely to conceive than cows with ULSOD(620) >0.058; moreover, the median calving-to-conception interval for cows that had ULSOD(620) ≤ 0.058 was 122 d compared with 148 d for cows that had ULSOD(620) >0.058. Cows that were positive for Arcanobacterium pyogenes, diagnosed with metritis, or had retained placenta had 4.0, 1.4, and 1.7 times higher odds of having ULSOD(620) >0.058, respectively. Cows with ULSOD(620) >0.058 had a higher percentage of neutrophils in the uterine lavage samples than cows with ULSOD(620) ≤ 0.058. Uterine lavage sample optical density measured at 620 nm can be used as an objective indicator of uterine health in dairy cows, principally for clinical endometritis.

Evaluation of vaginoscopy for the diagnosis of clinical endometritis in dairy cows

The objective of the study was to evaluate the visual assessment of vaginal discharge by vaginoscopy for the diagnosis of clinical endometritis (CE) in dairy cows. In an in vivo trial, inter- and intraobserver repeatability of vaginoscopic examination (VE) was determined and the effect of transrectal palpation and experience of the investigator evaluated. Holstein-Friesian cows (n=380) were examined by vaginoscopy between 21 and 27 d in milk by 3 investigators twice. Vaginal discharge was categorized on a 4-point classification system (0=clear mucus, 1=mucus containing flecks of pus, 2=discharge containing less than 50% pus, 3=discharge containing more than 50% pus). Cows with a vaginal discharge score (VDS) of 0 were classified as healthy, whereas cows with a VDS of 1 to 3 were classified as having CE. Vaginal discharge score on a scale from 0 to 3 has moderate intra- (Cohen's kappa coefficient, κ=0.55-0.60) and interobserver (κ=0.44) repeatability. The prevalence of CE was comparable between the 3 investigators (first VE: 42.6, 34.8, and 38.7; second VE 46.8, 36.9, and 43.7%). Transrectal palpation (relative risk=0.96-1.03) or experience of the investigator (relative risk=0.9-1.1) did not affect results of VE. In an in vitro trial, sensitivity and specificity of visual assessment were determined utilizing 33 images showing yellow and pink areas in certain percentages as a reference standard. Pus was represented by yellow areas and the mucosa, including clear mucus, by pink areas. These images were visually assessed by 30 investigators via PowerPoint presentation (experiment 1) and by 23 investigators via a simulated vaginal examination (experiment 2) utilizing the same 4-point classification system. Sensitivity was 99.6 and 96.3% and specificity was 96.7 and 90.1% in experiments 1 and 2, respectively. The results provide evidence that a visual assessment conducted by vaginoscopic examination is not perfect but can be considered a reasonable measurement of vaginal discharge and is a practical tool to distinguish healthy from diseased cows.

The influence of genital tract status in postpartum period on the subsequent reproductive performance in high producing dairy cows

The aim of the present study was to characterize the early postpartum period in clinically healthy dairy cows by ultrasonography (US), endometrial cytology (EC), and white blood cell counts, and determine possible relationships between postpartum findings and subsequent reproductive performance. Fifty-three dairy cows were examined on Days 15 to 21 (Visit 1), 22 to 28 (Visit 2), and 29 to 35 (Visit 3) postpartum. The clinical examination included: examination of vaginal fluid, EC, transrectal palpation and ultrasonography of the genital tract (cervical diameter, endometrial thickness, presence of a corpus luteum [CL] or intrauterine fluid [IUF] and its echogenicity). Luteal activity (presence of a CL in a single visit), return to cyclicity (presence of a CL in 2 consecutive visits), and conception rate at 70 and 120 days postpartum were considered as the dependent variables in four consecutive binary logistic regression analyses. Factors affecting leukocyte counts were established by general linear model (GLM) repeated measures analysis of variance. Based on the odds ratio (OR), the likelihood of luteal activity was higher in multiparous than primiparous cows (OR = 3.75) and tended to diminish in cows showing increased endometrial thickness in Visit 1 (V1) (OR = 0.06). The likelihood of returning to cyclicity decreased for each centimeter increase in cervical diameter in V1 (OR = 0.14) and that of conception on Day 70 was lower in cows showing the presence of echogenic or anechogenic IUF in V1 (OR = 0.09 or OR = 0.13, respectively) compared with cows lacking IUF. Effects of parity and IUF were observed on neutrophil counts. Positive EC results were unrelated to the cumulative conception rate at 70 and 120 days in milk, whereas cows returning a positive EC result in V1 showed a greater likelihood of increased endometrial thickness. In conclusion, measuring cervical diameter, endometrial thickness, and detecting the echogenicity of IUF by ultrasonography from Days 15 to 21 postpartum in clinically normal cows is an appropriate tool to predict subsequent reproductive performance. Vaginal examination and transrectal palpation alone did not emerge as valuable predictors.