Morphological changes in bitches endometrium affected by cystic endometrial hyperplasia - pyometra complex - the value of histopathological examination

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.

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.

A study on the correlation between intrauterine microbiota and uterine pyogenesis in dogs

Pyometra is a common and high-incidence reproductive system disease in female dogs, and its development involves both hormonal and bacterial factors. Characterization of the endometrial microbiome in healthy dogs and diseased dogs with pyometra remains unclear at present, however. In this study, dogs with pyometra were identified based on the clinical examinations, hematology examinations, vaginal smears and uterine histopathology. The endometrial samples of healthy dogs (n = 30) and diseased dogs (n = 41) were then collected and sequenced by 16S rRNA high-throughput sequencing technology. Dogs with pyometra suffered from inflammation, and their endometrial microbial diversity (ACE and Chao 1 indices) was significantly lower than that of healthy dogs (P < 0.05). The endometrial samples of both groups were enriched in four phyla (Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria), with a greater abundance of Firmicutes in diseased dogs (P < 0.05). At the genus level, the most prevalent microbes in diseased dogs belonged to Pseudomonas, Escherichia-Shigella, Mycoplasma, Enterococcus, Haemophilus, Vibrio and Ralstonia, with lower levels of Mycoplasma, Enterococcus and Haemophilus in the healthy control. Principal co-ordinates analysis and non-metric multi-dimensional scaling showed that the endometrial microbiome of diseased dogs clustered separately from that of the healthy controls (P < 0.05). In the LDA effect size analysis, 18 members of the endometrial microbiome were screened. Of these, the bacterial species Pseudomonas_aeruginosa and microbes within the genera Mycoplasma, Enterococcus and Haemophilus were found to be enriched in the uteruses of diseased dogs. Furthermore, the Random Forests model further confirmed that Mycoplasma and Haemophilus could be considered as biomarkers of diseased endometrium. In conclusion, this study provided a theoretical basis for the development of probiotic preparation in the future.

Identification of Canine Pyometra-Associated Metabolites Using Untargeted Metabolomics

Canine pyometra frequently occurs in middle-aged to older intact bitches, which seriously affects the life of dogs and brings an economic loss to their owners. Hence, finding a key metabolite is very important for the diagnosis and development of a new safe and effective therapy for the disease. In this study, dogs with pyometra were identified by blood examinations, laboratory analyses and diagnostic imaging, and fifteen endometrium tissues of sick dogs with pyometra and fifteen controls were collected and their metabolites were identified utilizing a UHPLC-qTOF-MS-based untargeted metabolomics approach. The results indicated that the elevated inflammatory cells were observed in dogs with pyometra, suggesting that sick dogs suffered systemic inflammation. In the untargeted metabolic profile, 705 ion features in the positive polarity mode and 414 ion features in the negative polarity mode were obtained in endometrium tissues of sick dogs with pyometra, with a total of 275 differential metabolites (173 in positive and 102 in negative polarity modes). Moreover, the multivariate statistical analyses such as PCA and PLS-DA also showed that the metabolites were significantly different between the two groups. Then, these differential metabolites were subjected to pathway analysis using Metaboanalyst 4.0, and Galactose metabolism, cAMP signaling pathway and Glycerophospholipid metabolism were enriched, proving some insights into the metabolic changes during pyometra. Moreover, the receiver operating characteristic curves further confirmed kynurenic acid was expected to be a candidate biomarker of canine pyometra. In conclusion, this study provided a new idea for exploring early diagnosis methods and a safe and effective therapy for canine pyometra.

Expression of Transforming Growth Factor Beta Isoforms in Canine Endometrium with Cystic Endometrial Hyperplasia-Pyometra Complex

Simple Summary

Pathomorphological changes and functional disorders of the uterus have long been a significant problem in the reproduction of dogs. The most commonly identified uterine disorders leading to permanent loss of fertility in dogs include cystic endometrial hyperplasia (CEH) and pyometra. These diseases may occur jointly as a CEH–pyometra complex. Despite numerous studies, the etiology of this disease remains unclear. TGF-β is considered to be one of the key factors in pathophysiological uterine disorders. The results indicate the significant expression of TGF-β1 in endometrial tissues in bitches affected by CEH–pyometra complex. Consequently, among all TGF-β isoforms, TGF-β1 is a potential biomarker involved in the regulation of a dog’s endometrium with proliferative and degenerative changes.

Abstract

Cystic endometrial hyperplasia (CEH) and pyometra are the most frequently diagnosed uterine diseases affecting bitches of different ages. Transforming growth factor beta (TGF-β) has been classified in females as a potential regulator of many endometrial changes during the estrous cycle or may be involved in pathological disorders. The aim of this study was to determine the expression of TGF-β1, -β2 and -β3 in the endometrium of bitches suffering from CEH or a CEH–pyometra complex compared to clinically healthy females (control group; CG). A significantly increased level of TGF-β1 mRNA expression was observed in the endometrium with CEH–pyometra compared to CEH and CG. Protein production of TGF-β1 was identified only in the endometrium of bitches with CEH–pyometra. An increase in TGF-β3 mRNA expression was observed in all the studied groups compared to CG. The expression of TGF-β2 mRNA was significantly higher in CEH and lower in CEH–pyometra uteri. The results indicate the presence of TGF-β cytokines in canine endometrial tissues affected by proliferative and degenerative changes. However, among all TGF-β isoforms, TGF-β1 could potentially be a key factor involved in the regulation of the endometrium in bitches with CEH–pyometra complex.