Histopathologic findings in uterine biopsy samples from subfertile bitches: 399 cases (1990-2005)

Causes of pregnancy arrest in the canine species

In the canine species, early pregnancy arrest before 30-40 days of pregnancy will induce intra-uterine embryonic or foetal resorption, with very few clinical signs. If no genital examination by ultrasound is performed at that time, it will often remain unnoticed and the bitch will be qualified as infertile. It is only when pregnancy stops at a later stage, mostly after 40 days, that clinical signs will be seen. Expulsion of aborted foetuses or placentas may be observed, although the dam frequently eats the expelled tissues. Intra-uterine mummification may also occur. This article reviews the causes of pregnancy termination in the bitch, both at the embryonic and the foetal stages, reported in the literature. Canine brucellosis is by far the most important disease concerned in this aspect. There is an important current concern about this disease, due to the fact that several outbreaks have been observed recently in Europe, and that it is a very contagious disease; it may be an underestimated zoonosis. Other bacterial causes of pregnancy arrest are sporadic. There is, however, a growing attention towards the microbiological content of raw food diets which are more and more popular among dog breeders and may-if badly prepared-contain abortifacient bacteria such as Campylobacter jejuni or Listeria monocytogenes. The abortifacient role of endogenous vaginal bacteria and mycoplasms remains unclear and may be related to an imbalanced vaginal flora with subsequent ascending bacterial contamination of the uterus. The role of Canine Herpesvirus on abortion is controversial and probably not frequent. Other viruses have been shown experimentally to induce abortion but their natural occurrence in this respect remains unknown. The same applies to the parasite Neospora caninum which is suspected, but not proven, potentially to induce pregnancy arrest in bitches. Among non-infectious causes, uterine pathology such as cystic endometrial hyperplasia (CEH) or sub-clinical post-mating endometritis which can cause infertility and may also induce embryonic resorption. The role of luteal insufficiency in pregnancy arrest is probably overestimated.

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.

Infertility In Queens: Clinical approach, experiences and challenges

CLINICAL CHALLENGES

It is not easy for a veterinarian to determine the cause of infertility in a queen. The simplest method is to start by investigating the most common causes and then progress by successive elimination to the less common causes. For example, mating problems are commonly responsible for reproductive failure, and owners should be particularly vigilant in checking that the mating is progressing satisfactorily. Frequently, a veterinarian may have to determine, among other things, if there is a uterine or hormonal disorder or if an infectious pathology may be involved. In the case of a queen that is not cycling, it is important to differentiate a lack of onset of puberty in a young queen from a lack of cyclicity in an adult queen.

AIM

This review sets out a practical, step-by-step approach that veterinarians can follow, starting with the most common causes of infertility in queens and moving towards more rare or specific causes.

EQUIPMENT AND TECHNICAL SKILLS

Simple techniques such as vaginal smears are essential to determine if a queen that is ready to be mated is in full oestrus, if a queen is cycling or not and to diagnose inflammation of the genital tract. Veterinarians should be familiar with the peculiarities of the swabbing technique in cats, as well as the interpretation of feline vaginal cytology. Progesterone assays are useful on many occasions in the diagnosis pathway. A laboratory capable of performing karyotypes should ideally be available. Finally, it is important to be able to perform an ultrasound examination of the ovaries and uterus in a queen.

EVIDENCE BASE

Although it appears that infertility is a problem among purebred queens, there is a lack of knowledge in this area and too few published studies. Some causes of feline infertility remain poorly investigated.

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

BACKGROUND

Cystic endometrial hyperplasia-pyometra complex (CEH-P) is one of the most common uteropathies in bitches. In diseases with mild or obscure clinical signs and normal uterine size, a diagnosis based on a clinical assessment might be incorrect. The main aim of the research was to determine the morphological variables accompanying uterine diseases in bitches in microscopic evaluation. Consequently, the obtained results can be used to create a new classification system for uterine pathological changes during the development of the CEH-P, diagnosed by microscopic examination in bitches. Material for the study consisted of the uteri of 120 female dogs, aged 1-16 years, obtained during routine ovariohysterectomies. Macroscopic observation after a longitudinal incision of the uterine horns, allowed a preliminary classification of the uteri into research groups: control group (physiological uteri), and groups GI-III uteri collected form bitches with varying degrees of endometrial pathology. These preliminary classifications were then verified by histological analysis (H&E stain).

RESULTS

The obtained results made it possible to determine and describe the prevalence (%) of pathological changes characteristic of the analyzed uterine diseases in the examined bitches. Histopathological analyses that were conducted have confirmed preliminary macroscopic evaluation for the control group, group GII (CEH), and group GIII (pyometra). In the uteri of the GI group, a severe congestion of the endometrium has been observed - this is typical of inflammation - which was not confirmed during histopathological examinations. However, these examinations revealed acute endometrial haemorrhage of varying severity.

CONCLUSIONS

Early reproduction disorders in bitches are, in general, not confirmed by clinical signs in the examined animals. The results show that during classification of typical morphological changes in the endometrium over the development of the CEH-P complex in bitches microscopic examinations are required. The obtained results indicate a frequent lack of consistency in the macroscopic assessment and histological analysis of the endometrium, observed in the analyzed uterine diseases, which in most cases is not followed by clinical symptoms. The presented classification of uterine diseases may be useful as a diagnostic tool in reproductive disorders in bitches and in examination in the field of basic research.

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.

Infertility in purebred cats - A review of the potential causes

Although purebred cat breeding is growing in popularity in European countries, most research and publications concern dog reproduction. Infertility in queens has been poorly studied. It may not come as a surprise as common domestic shorthair cats are well known for their excellent fertility. However, even in the latter, the infertility rate is around 20%. Only recently, published articles have analyzed the reproductive performances in different breeds, for example in UK, Sweden, France and Italy, and found similar figures. In cats, infertility may arise from many factors such as mismating, prolonged anestrus or silent heats, hormonal, nutritional, genetical or chromosomal causes. Also, infectious diseases, probably frequent in breeding facilities, include pathological agents that are well recognized as having a negative effect on pregnancy or other pathogens for which the involvement in fertility problems is unclear. However, analyzing the literature, it appears that the most prevalent causes of infertility in pedigree cats may well be, in females, uterine pathology (sub-clinical endometritis, cystic endometrial hyperplasia, or mucometra), and in males, teratospermia, which may be "permanent" and linked to reduced heterozygosity or "transient" in tomcats that present normal quantitative spermatogenic parameters. The influence of the breed is unknown. There is an urgent need to study the origin of infertility in purebred cats in order to improve the diagnosis and to develop treatments that may restore normal fertility in subfertile or infertile animals.

Contrast-Enhanced Ultrasound in Cystic Endometrial Hyperplasia-Pyometra Complex in the Bitch: A Preliminary Study

Simple Summary

In canine cystic endometrial hyperplasia–pyometra (CEH) syndrome, toxic factors and endometrial inflammatory reactions are responsible of increased blood flow and lower vascular resistance in uterine arteries. Color Doppler ultrasound is regarded as an adjunctive tool for quantitative assessment of endometrial vascularization during uterine disorders. The aim of this study was to assess, through contrast-enhanced ultrasound (CEUS) exam, the vascularization in endometrial microvessels in CEH-pyometra in order to evaluate the possibility of application in this syndrome. In twelve female dogs with clinical symptoms related to pyometra, echographic, Color Doppler and CEUS exams were performed. Histopathological examination revealed severe CEH and pyometra, immunohistochemical stain with CD 34 confirmed the presence of angiogenesis. CEUS exam revealed a widespread, intense and rapidly developing homogeneous enhancement of the hyperplastic endometrium with absence of signal only in cystic areas. All parameters of the quantitative analysis were not significantly influenced by region of interest dimension and position. CEUS may improve not invasive evaluations in the CEH-pyometra syndrome and virtually in CEH-mucometra.

Abstract

In cystic endometrial hyperplasia (CEH)–pyometra syndrome, toxic factors and endometrial remodeling culminate in changes characterized by exudative and degenerative inflammatory reaction. Recent studies on hemodynamic found an increased blood flow and lower vascular resistance in uterine arteries, suggesting color Doppler ultrasound as an adjunctive tool for quantitative assessment of endometrial vascularization during pyometra. The aim of this study was to assess, through contrast-enhanced ultrasound (CEUS) exam, the vascularization in endometrial microvessels in CEH-pyometra in order to evaluate the possibility of application in this syndrome. In twelve female dogs with clinical symptoms related to pyometra, B-mode, color Doppler and CEUS exams were performed. In CEH-pyometra uteri, histopathological examination revealed severe CEH and pyometra, immunohistochemical stain with CD 34 confirmed the presence of angiogenesis. CEUS exams revealed a widespread, intense and rapidly developing homogeneous enhancement of the hyperplastic endometrium, with absence of signal only in cystic areas. All parameters of the quantitative analysis were not significantly influenced by region of interest dimension and position. CEUS has the potential to improve clinical not invasive evaluations in the CEH-pyometra syndrome and virtually in CEH-mucometra.

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.

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.

Infertility associated with the absence of endometrial progesterone receptors in a bitch

A three-year-old intact female Old English sheepdog was presented for evaluation of infertility. A uterine biopsy was performed during dioestrus, and the microscopic appearance was inconsistent with progesterone stimulation; the glands were sparse, simple and failed to show coiling, while the glandular epithelium was cuboidal instead of columnar. There was very little evidence of glandular activity. Due to the inappropriate appearance of the glands for the stage of the cycle, immunohistochemistry for progesterone receptors was performed. No progesterone receptor-positive immunoreactivity was identified in the endometrial luminal epithelium, glandular epithelium or stroma. Weak intranuclear immunoreactivity was identified within the smooth muscle cells of the myometrium. The absence of progesterone receptors within the endometrial glands is the most likely explanation for the abnormal appearance of the endometrium and for this bitch's infertility. To our knowledge, this is the first report of endometrial progesterone receptor absence in a bitch.