Uterine endometrial cytology, biopsy, bacteriology, and serum C-reactive protein in clinically healthy diestrus bitches

The reproductive microbiome in dogs: Friend or foe?

The microbiome of the reproductive tract is an area of research in full development. Specifically, the microbiome may be involved in reproductive health, disease, and pregnancy outcomes, as has been shown in humans and animals, including dogs. The aim of the present review was to summarize current knowledge on the microbiome of the canine reproductive tract, to expose the controversial role that some bacterial agents may play in canine subfertility, and to highlight future research perspectives. This review discussed whether the use of antimicrobials in dogs is appropriate to increase reproductive performance and to treat subfertility without proper diagnosis, and the possible use of probiotics to modulate the reproductive canine microbiome. Finally, we indicate areas in which scientific knowledge is currently lacking, and could be promising directions for future research.

General and comparative aspects of endometritis in domestic species: A review

Endometritis is a leading cause of sub- and infertility in domestic animal species. The healthy uterus is colonized by commensal bacteria, viruses and yeast/fungi that represent the nonpathogenic microbiota. A shift in the number or type of organisms accompanied by immune dysfunction, however, may trigger uterine infection and inflammation. Metritis is associated with inflammation of all uterine layers (endometrium, myometrium and perimetrium), whereas endometritis is a more superficial inflammation involving solely the endometrium. Endometritis generally occurs at two time points in domestic animal species, postpartum and postmating. Postpartum endometritis may chronically persist, either as a low-grade disease that often manifests as a vaginal discharge but not a systemic illness (in some species termed clinical endometritis) or sometimes subclinical where features are only detected by endometrial sampling. Contamination of the uterus at the time of mating occurs by direct deposition of semen (ejaculated or artificially inseminated) into the uterus. Improper drainage of the ejaculatory fluid or an inadequate immune response may result in persistent mating-induced endometritis. Both postpartum and postmating endometritis interferes with fertility by creating a suboptimal environment for embryo development and placentation, and chronic endometritis may have an impact on sperm survival and fertilization ability. In the postpartum animal, there may also be changes in milk production and maternal behaviour, which can affect offspring health and survival. Preventive strategies for endometritis largely depend on monitoring their known risk factors, which are sometimes specific with regard to the species. Effective, nonantibiotic therapy for endometritis is not available to date. Overall, extensive research has been performed in cattle and horses to unravel key aspects of endometritis, but in sows and bitches, the available literature is scant. Thus, the need and opportunity to investigate the condition vary considerably among domestic species and necessitate their comparative assessment. This article reviews general and comparative aspects of the diagnosis and classification, pathogenesis, preventive strategies and therapeutics of endometritis in domestic species with a specific focus on cows, mares, sows and bitches.

Uterine issues in infertile queens: nine cases

This prospective case series investigated potential uterine causes of infertility in queens. Purebred queens with infertility (failure to conceive, embryonic death, or failure to maintain pregnancy and produce viable kittens), but no other reproductive disorders were examined approximately 1-8 weeks before mating (Visit 1), 21 days after mating (Visit 2), and 45 days after mating (Visit 3) if pregnant at Visit 2. Investigations included vaginal cytology and bacteriology, urine bacteriology, and ultrasonography. At Visit 2 or 3, uterine biopsy or ovariohysterectomy was performed for histology. Of nine eligible queens, seven were non-pregnant by ultrasound at Visit 2 and two had lost pregnancies by Visit 3. Ovulation was confirmed by serum progesterone concentration in all queens. Ultrasonic appearance of the ovaries and uterus was compatible with a healthy status except for one queen with signs of cystic endometrial hyperplasia (CEH) and pyometra, a follicular cyst in another, and fetal resorptions in two queens. Six cats had histologic lesions of endometrial hyperplasia, including CEH (n=1). Only one cat had no histologic uterine lesions. Bacteria were cultured from vaginal samples in seven queens at Visit 1, (two were non-evaluable), and in five of seven queens sampled at Visit 2. Uterine cultures were negative except for the cat with pyometra. All urine cultures were negative. In summary, the most frequent pathology observed in these infertile queens was histologic endometrial hyperplasia, which can potentially inhibit embryo implantation and healthy placental development. This suggests that uterine disease might contribute substantially to infertility in purebred queens.

Endometrial Status in Queens Evaluated by Histopathology Findings and Two Cytological Techniques: Low-Volume Uterine Lavage and Uterine Swabbing

Simple Summary

The endometrium health of feline queens can be difficult to assess due to the reduced size of the uterus, which hinders representative biopsy sampling. This may result in limitations in diagnosing endometritis, and consequently in detecting infertility problems. Although histology is considered the most reliable technique for diagnosing endometritis in many species, cytology is also gaining importance and may be an alternative tool for evaluating the endometrium in small species. Two different common cytological techniques (uterine lavage and uterine swabbing) were compared to determine the reliability of cytology for evaluating the endometrium status in queens. Histopathological and bacteriological information was used for the control methods. Our results demonstrated that cytology may be a useful diagnostic tool for assessing the endometrial status. In addition, when comparing cytological techniques, the uterine lavage method was more representative than uterine swabbing.

Abstract

Endometritis is associated with fertility problems in many species, with endometrial biopsy being the main diagnostic tool. In feline queens, the reduced size of the uterus may make it difficult to obtain representative diagnostic samples. Endometrial cytology may represent a valuable diagnostic tool for evaluating the health status of the endometrium in queens. Fifty domestic shorthair queens were included and divided into two cytological diagnostic technique groups, the uterine lavage (UL; n = 28) and uterine swabbing (US; n = 22) groups. Cytological results were compared with histopathological and bacteriological information. Changes in the histopathological patterns were also evaluated and compared with progesterone levels to confirm previous published data. Furthermore, the results from both cytological sampling methods were compared to evaluate the utility of each method. Endometritis was ruled out in all queens by means of histology and microbiology. Leukocyte counts and red blood cell/endometrial cell ratios were significantly higher in US than UL samples. Additionally, UL sampling is less affected by blood contamination and cells are better preserved. The combination of endometrial cytology and uterine culture might be useful for evaluating the endometrial characteristics in queens. The UL evaluation method is more representative of the actual endometrial status than the US technique.

Normal and abnormal response to sperm deposition in female dogs: A review and new hypotheses for endometritis

In mammalian species there are significant physiological responses of the female reproductive tract to the deposition of sperm. These are particularly notable in species where sperm are deposited directly into the uterus, and function both to facilitate sperm transport to the sperm reservoir, and to eliminate introduced contaminants. In the bitch, sperm are deposited into the vagina and are rapidly transported through the open cervix. Sperm are then distributed around the uterus by uterine contractions such that transportation to the tip of the uterine horns occurs within 1 min of the start of mating. The main sperm reservoir appears to be the distal part of the utero-tubal junction which forms a pre-uterine tube reservoir. Sperm remain attached here by their heads to uterine epithelium and remain viable. In non-capacitating conditions sperm slowly detach from this site and this seems important to replenish the uterine tube reservoir, where sperm may re-attach to the epithelium. Post-ovulatory signals trigger capacitation changes and subsequent hyperactivated motility that is associated with detachment of sperm from both reservoirs; thus facilitating fertilization. After mating, a physiological post-mating uterine inflammatory response occurs, evidenced by an influx of polymorphonuclear neutrophils, increased uterine contractions, an increased uterine artery blood flow and a decrease of the resistance index indicating a short-duration vasodilation. Disturbance of this tightly regulated system has the potential to impact fertility by a failure of elimination of the introduced contaminants (such that a clinically-significant post-breeding endometritis ensues) but also by impairing sperm transport.

Serum progesterone concentration, volume, and apoptosis of corpora lutea in early, middle and late diestrus in the bitch

The aim was to study number, volume, apoptosis of corpora lutea (CL), and serum P₄ concentrations in early, middle, and late diestrus of dogs. Thirty-six bitches were ovari-hysterectomized (OVX): Early Diestrus (Group [G]1; OVX 20 days after end of estrus [DEH]); Mid-diestrus (GII; OVX between 21 and 40 days after DEH), and Late-diestrus (GIII; OVX between 41 and 60 days after DEH). Before OVX a blood sample was collected to quantify P₄. After OVX, the number of CL (NCL) was recorded, CL measured using both ultrasonography (US) and caliper (CAL), and the volume (mm³) was calculated. Based on abundances of caspase-3, apoptotic luteal cells were detected. Bitches in early-diestrus had greater P₄ concentrations than bitches in mid- and late-diestrus (23.52 ± 3.78 and 10.86 ± 3.88 ng/mL; P < 0.05). The NCL, cumulative USCLV, and CALCLV were similar among diestrus stages (P > 0.30). Bitches with CL (≥5) had twice the serum P₄ concentrations as bitches with CL1-2 and CL3-4 (22.71 ± 3.70 and 10.97 ± 4.06 ng/mL; P < 0.05). There were correlations between P₄ concentrations with USCLV, CALCLV, and NCL (r = 0.64, r = 0.67, r = 0.44; P < 0.0001). When serum P₄ concentrations were adjusted for stages of diestrus, however, there were only correlations during early diestrus. The percentage of apoptotic cells was greater in GIII compared with GI and GII (13.75 ± 2.26 % compared with 4.5 ± 0.68 % and 4.6 ± 1.5 %, respectively; P < 0.05). As days of diestrus increased, number of apoptotic cells increased, and serum P₄ concentrations decreased.

Endometritis in the bitch: Immunohistochemical localization of cyclooxygenase 2

Background:

In several mammals, subfertility or infertility associated with endometritis was reported. Although there have been studies about endometritis in bitches, the pathophysiological mechanisms are not completely known.

Aim:

This study aimed to evaluate the immunohistochemical expression of Cyclooxygenase 2 (COX2) in clinically healthy bitches with normal uterine tissue and bitches with endometritis.

Methods:

Forty-eight mixed breed bitches in diestrus were used. Uterine biopsies were collected for diagnosis [normal endometrium (n = 15; NE), cystic endometrial hyperplasia (n = 1), atrophy (n= 2), acute endometritis (n = 9; AE), subacute endometritis (n = 7; SE), and chronic endometritis (n = 14; CE)]. Immunostaining and quantification of positively stained cells was performed on full-thickness uterine biopsies. Data were analyzed by the GLIMMIX procedure of SAS.

Results:

COX2 immunostaining was scattered and restricted to cells in the stroma in bitches with NE. However, in bitches with endometritis, strong staining was observed in the luminal epithelium, glandular epithelium, and stromal cells. Staining was also observed in inflammatory cells localized in the stroma as well as inside of the glands. The percentage of COX2 positive stromal cells in bitches with AE, SE, and CE was significantly higher compared with NE (p < 0.005). In addition, the percentage of COX2 positive stromal cells in bitches with SE, and CE was significantly lower compared with AE (p < 0.003).

Conclusion:

COX2 could be involved in the pathophysiological mechanisms producing endometritis without the presence of cystic endometrial hyperplasia in bitches. However, further researches on this topic are required.