Perturbed sperm–epithelial interaction in bitches with mating-induced endometritis

The Impact of Microorganisms on Canine Semen Quality

Various microorganisms, including Mycoplasma spp., have been reported in canine ejaculate. The impact of these microorganisms on semen quality remains unclear. This study included 63 male intact healthy dogs aged 1-8 years. One dog exhibited azoospermia, indicating a relatively low incidence of this condition. Interestingly, 36.5% of the examined dogs tested negative for both aerobic bacteria and mycoplasmas, while 12.7% tested positive for bacterial presence. Additionally, 60.3% of the dogs tested positive for Mycoplasma spp. using PCR, with most carrying 1-2 Mycoplasma species. We found no significant difference in semen characteristics between Mycoplasma-positive and -negative dogs. The detection of Mycoplasma was not significantly linked to the presence of bacteria in semen. All the microorganisms identified were classified as saprophytic flora. Our findings indicate that Mycoplasma spp. is common in canine ejaculate. Semen quality parameters were not correlated with the presence of Mycoplasma spp. in semen. Mycoplasma HRC689 was the most common species. Some dogs exhibited no presence of aerobic bacteria or mycoplasmas in their semen. Our study highlights the common presence of Mycoplasma spp. in canine ejaculate. Semen quality shows no correlation with Mycoplasma presence. Some canine ejaculate is sterile. Our findings suggest the existence of undescribed species of canine mycoplasmas, necessitating advanced diagnostic techniques like NGS for their identification.

Cystic endometrial hyperplasia-pyometra syndrome impairs the preantral follicle reserve in domestic bitches (Canis familiaris)

Cystic endometrial hyperplasia (CEH)-pyometra syndrome is the most common uterine pathological condition reported in breeding bitches, however, their described effects on fertility are limited to uterine disorders and conception rates. As the preantral follicle population represents the available reserve of gametes recruited during the lifespan, the aim of this study was to evaluate the effects of CEH-pyometra syndrome on the: (i) preantral follicle morphology, (ii) developing follicle rates, and (iii) preantral follicle and stromal cell densities. Ovarian fragments from bitches subjected to elective or therapeutic ovariohysterectomy were allocated according to uterine diagnosis as follows: control (n = 7, clinically healthy), CEH-mucometra (n = 8, uterine lumen filled with a sterile mucus), and pyometra (n = 17, presence of a purulent mucus) groups. Overall, the control group had 3.4 and 4.1-fold higher probability (P < 0.0001) of the presence of normal preantral follicles compared with CEH-mucometra and pyometra groups, respectively. Moreover, ovarian fragments from the pyometra group showed an increase in the percentage of developing follicles (P < 0.05) compared to the control. Both CEH-mucometra and pyometra groups showed lower (P < 0.05) preantral follicle and stromal cell densities (P < 0.05) compared to the control. In summary, the CEH-pyometra syndrome decreased the percentage of morphologically normal follicles and enhanced the developing follicle rates. Additionally, a reduction of preantral follicle and stromal cell densities suggests that the inappropriate uterine environment induced by CEH-pyometra syndrome can lead to premature depletion of ovarian reserve.

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.

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.

Impaired inflammatory state of the endometrium: a multifaceted approach to endometrial inflammation. Current insights and future directions

New insights into the complex and fine-regulated inflammatory mechanisms involved in the endometrium reveal multiple facets to the problem of endometrial inflammation. However, the entity termed chronic endometritis is to date restricted to infectious etiology and managed with antibiotics. Conversely, the concept of impaired inflammatory state of the endometrium (IISE) provides a more global approach to defective endometrial inflammation, considering both infectious and non-infectious etiology. A non-systematic review was done through a search on MEDLINE, EMBASE, Global Health, The Cochrane Library, Health Technology Assessment Database and Web of Science, research registers. Pertinent original and review articles, published in English or French until December 31, 2019, were selected. A compelling body of evidence demonstrates transient, repeated and persistent IISE to be a major factor of most problematic disorders in obstetrics/gynecology, such as endometrial polyps, unexplained infertility, miscarriage, placenta-related pathology and endometrial cancer. When scheduled accordingly, hysteroscopy can play a key role in the IISE assessment. Robust data suggests the pertinence of minimal-effective anti-inflammatory regimens for therapeutic IISE targeting. This review provides a comprehensive update on the multiple facets of inflammation in the endometrial physiology and pathology. Further research is needed to improve classification, diagnosis and treatment of IISE.

Small animal reproduction: Scientific facts versus dogmas or unverified beliefs

Small Animal Reproduction is a rather recent topic in the field of Animal Reproduction. Although some continuing educational societies aim to improve the level of general knowledge, published scientific facts are still limited, and there are many hypotheses or affirmations that remain unverified or even sometimes dogmatic or empirical. Through examples, this article reviews the main causes that may sometimes challenge a veterinary practitioner faced with a dog or a cat presenting reproductive problems. It could be difficult to orientate the diagnosis or the therapeutic approach, not knowing if what is found in the literature is a scientific proof or just an unverified affirmation. This problem may result from the fact that there are still physiological processes that remain unclear, but also that some common beliefs are based on old studies that have not been repeated or verifiedIn addition, to make it more challenging to seek for the information, there are unverifiedaffirmations,unclear nomenclature, clinical conditions which have not been standardized in the literature, clinical conditions mostly described through case reports, lack of studies on specific topics, areas of small animal reproduction that have been neglected by researchers, contradictory data or even studies that lack objectivity. The growing interest for research in Small Animal Reproduction will probably reduce the gap between unverified beliefs and scientific facts.

The Female Response to Seminal Fluid

Seminal fluid is often assumed to have just one function in mammalian reproduction, delivering sperm to fertilize oocytes. But seminal fluid also transmits signaling agents that interact with female reproductive tissues to facilitate conception and .pregnancy. Upon seminal fluid contact, female tissues initiate a controlled inflammatory response that affects several aspects of reproductive function to ultimately maximize the chances of a male producing healthy offspring. This effect is best characterized in mice, where the female response involves several steps. Initially, seminal fluid factors cause leukocytes to infiltrate the female reproductive tract, and to selectively target and eliminate excess sperm. Other signals stimulate ovulation, induce an altered transcriptional program in female tract tissues that modulates embryo developmental programming, and initiate immune adaptations to promote receptivity to implantation and placental development. A key result is expansion of the pool of regulatory T cells that assist implantation by suppressing inflammation, mediating tolerance to male transplantation antigens, and promoting uterine vascular adaptation and placental development. Principal signaling agents in seminal fluid include prostaglandins and transforming growth factor-β. The balance of male signals affects the nature of the female response, providing a mechanism of ‟cryptic female choiceˮ that influences female reproductive investment. Male-female seminal fluid signaling is evident in all mammalian species investigated including human, and effects of seminal fluid in invertebrates indicate evolutionarily conserved mechanisms. Understanding the female response to seminal fluid will shed new light on infertility and pregnancy disorders and is critical to defining how events at conception influence offspring health.

Triplex doppler ultrasonography to describe the uterine arteries during diestrus and progesterone profile in pregnant and non-pregnant bitches of different sizes

Hemodynamics of uterine vascularization is modified throughout pregnancy to meet the increasing demand of the growing fetuses and triplex doppler ultrasonography is widely used in human medicine to study the uterine arteries and assess the fetal and placental conditions. The aim of our study was to confirm this observation in the bitch, to evaluate differences between bitches of different sizes and to study abnormal pregnancies. Forty-four bitches were monitored during the estrous period to determine ovulation and every 10 days from ovulation to 50 days post-ovulation: the resistivity (RI) and pulsatility (PI) indexes of the right uterine artery were measured as well as usual assessment of fetal development and follow up of the luteal function. Thirty-three out of forty-four bitches were pregnant, including 6 abnormal pregnancies (resorption of more than 10% of the embryos). We also divided them in four weight categories: 8 were small (<10 kg), 13 medium (10-25 kg), 13 large (>25-40 kg) and 10 were giant breeds (>40 kg). We observed that RI and PI decreased over time and were significantly lower for pregnant bitches compared to non-pregnant ones from 30 days post-ovulation. In contrast, RI and PI did not significantly vary with the size of the bitches and we could not determine a significant impact of abnormal pregnancies either. In conclusion, we found no significant difference related to the size of bitches in the RI and PI. The only significant difference between pregnant and non-pregnant bitches was observed from 30 days post-ovulation.

Spontaneous ovulation in cats-Uterine findings and correlations with animal weight and age

Cats are considered induced ovulating animals but ovulations occur in the absence of mating (i.e., spontaneous ovulations). Factors that stimulate such ovulations remain largely unknown. In this study, ovaries and uterine horn segments from 89 post-pubertal queens presented for ovariectomy were evaluated morphologically and histologically. It was hypothesized that corpora lutea (CL) are present in non-pregnant cats and can be associated with cystic endometrial hyperplasia (CEH). Cats were assigned to three age groups (7-12 months, n = 32; 13-24 months, n = 26 and ≥ 24 months, n = 31) and three weight groups (2.1-2.8 kg, n = 28; > 2.8-3.3 kg, n = 32 and > 3.3 kg, n = 29). Uterine horn diameter and thickness of the endometrium and myometrium were determined. Corpora lutea were detected in 39.3% of the cats and presence did not differ between age groups. The percentage of queens with CL increased with bodyweight (2.1-2.8 kg: 14.3%; > 2.8-3.3 kg: 37.5%, > 3.3 kg: 65.5%; P < 0.01). In cats with CL, the thickness of all layers of the uterus were greater than in cats without CL (P < 0.05). Of the cats, 22.5% had CEH but there was no difference between cats without and with CL. The percentage of CEH increased with age (P < 0.001) but did not differ between weight groups. In conclusion, ovulations occurred in the absence of mating in approximately one third of all queens.

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

The aim of this work was to assess the agreement between endometrial cytology and uterine biopsy for the diagnosis of endometritis (END), the bacterial populations isolated from the vagina and uterus of bitches having END, and the measurement of C- reactive protein as a diagnostic tool for diagnosis of END in clinically healthy bitches. Fifty privately-owned intact, clinically healthy bitches, in diestrus, without a history of progestin administration, aged between 8 months and 6 years old and weighing between 5 and 28 kg were used in this study. Bitches were included in a program for breeding control at a municipal pet public shelter. Before ovariohysterectomy (OVX) samples for vaginal cytology and bacteriology, and blood samples were taken. After OVX endometrial cytology, bacteriological samples and biopsy were collected. Histologic examination was performed to confirm the uterine condition. Blood samples were centrifuged and stored at -20 °C until progesterone (P₄) and C-reactive protein was measured. Samples for bacteriological culture were collected, and swabs were placed into Stuart's transport medium and transported to the laboratory. On histopathologic examination, the most common observation was END (27/50), followed by normal endometrium (NE; 18/50), cystic endometrial hyperplasia (CEH; 2/50), atrophy (2/50) and fibrosis with degeneration of the endometrial glands (1/50). Low degree of agreement was observed between results obtained by endometrial cytology samples and results obtained by biopsy in endometrial diagnosis (Kappa Coefficient: -0.19). In vaginal samples, β-hemolytic Streptococcus, Staphylococcus spp., Escherichia coli, Proteus spp., Corynebacterium spp., and Klebsiella pneumoniae were the bacteria most often found. In uterine samples, only four samples from END showed bacterial grow. C-reactive protein frequency was higher in END (6/23, 23%) vs NE (0/16, 0%; Van der Waerden P-value = 0,0302). Our results support the hypothesis that END is a frequent finding in uterine biopsy and could be associated with subfertility and infertility in the bitch. A low degree of agreement was observed between the diagnostic results from the uterine biopsy and endometrial cytology. Bacteriology would not be recommended as a diagnostic tool because no bacteria highly associated with uterine diseases were isolated from bitches with END. Finally, the usefulness of C-reactive protein concentration as a marker for END in bitches could not be conclusively demonstrated.

Deep sequencing of the uterine immune response to bacteria during the equine oestrous cycle

Background

The steroid hormone environment in healthy horses seems to have a significant impact on the efficiency of their uterine immune response. The objective of this study was to characterize the changes in gene expression in the equine endometrium in response to the introduction of bacterial pathogens and the influence of steroid hormone concentrations on this expression.

Methods

Endometrial biopsies were collected from five horses before and 3 h after the inoculation of Escherichia coli once in oestrus (follicle >35 mm in diameter) and once in dioestrus (5 days after ovulation) and analysed using high-throughput RNA sequencing techniques (RNA-Seq).

Results

Comparison between time points revealed that 2422 genes were expressed at significantly higher levels and 2191 genes at significantly lower levels 3 h post inoculation in oestrus in comparison to pre-inoculation levels. In dioestrus, the expression of 1476 genes was up-regulated and 383 genes were down-regulated post inoculation. Many immune related genes were found to be up-regulated after the introduction of E. coli. These include pathogen recognition receptors, particularly toll-like receptors TLR2 and 4 and NOD-like receptor NLRC5. In addition, several interleukins including IL1B, IL6, IL8 and IL1ra were significantly up-regulated. Genes for chemokines, including CCL 2, CXCL 6, 9, 10, 11 and 16 and those for antimicrobial peptides, including secretory phospholipase sPLA₂, lipocalin 2, lysozyme and equine β-defensin 1, as well as the gene for tissue inhibitor for metalloproteinases TIMP-1 were also up-regulated post inoculation.

Conclusion

The results of this study emphasize the complexity of an effective uterine immune response during acute endometritis and the tight balance between pro- and anti-inflammatory factors required for efficient elimination of bacteria. It is one of the first high-throughput analyses of the uterine inflammatory response in any species and several new potential targets for treatment of inflammatory diseases of the equine uterus have been identified.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-2139-3) contains supplementary material, which is available to authorized users.

Diseases of the canine uterus

Lesions most commonly found in the canine and feline uteri fall primarily into two categories: (i) abnormalities of endometrial growth and repair and (ii) uterine infections with associated endometritis. Neoplastic conditions of the tubular genitalia of the bitch, with the possible exception of leiomyomas (tumours that arise from smooth muscle cells), are uncommon. Congenital lesions involving the uterus are relatively rare. The primary object of this paper is to provide a summary of the most common uterine lesions found in the canine and feline uterus using a series of images that underscore the most prominent and important gross diagnostic features of each.

Prevalence and effect of uterine luminal free fluid on pregnancy and litter size in bitches

Free fluid within the uterine lumen has been identified ultrasonographically as a transient finding in normal bitches in the period immediately after mating, and delayed clearance of the fluid has been documented in bitches with endometrial hyperplasia. This study used B-mode ultrasonography to investigate the prevalence of free fluid in the uterine lumen in normal bitches (n = 53) and bitches with endometrial hyperplasia (n = 10) on Days -7, 0, +5, and +14 in relation to estimated ovulation. For normal bitches without endometrial hyperplasia, 47 (86.6%) bitches become pregnant, whereas for bitches with endometrial hyperplasia, 3 (30%) become pregnant. In both the groups, the presence of uterine fluid on Days -7 and 0 was not associated with the probability of a bitch becoming pregnant, whereas the presence of uterine fluid on either Day +5 or +14 was significantly associated with a reduced likelihood of pregnancy. In pregnant bitches, uterine luminal fluid present on Day 0 was associated with a smaller litter size. This is the first study to establish the prevalence and effect of uterine luminal free fluid in bitches. We postulate that as the uterine luminal free fluid may be detected in normal bitches before mating and has no effect on the pregnancy rate or litter size in either group, this fluid is "physiological." However, it seems that the later in estrus the uterine fluid is present, the more likely it is to have an adverse effect on fertility. In some cases, this is manifest as a reduced litter size, while, importantly, the presence of fluid 5 to 14 days after ovulation is strongly associated with an absence of pregnancy, both in bitches with and without endometrial hyperplasia. We propose that ultrasonographic detection of uterine luminal free fluid after mating may be a useful prognostic indicator for pregnancy outcome, which may allow the targeting of treatments specifically to a population of animals that presumably develop mating-induced endometritis.