Measurement of C-reactive protein and Prostaglandin F2αMetabolite Concentrations in Differentiation of Canine Pyometra and Cystic Endometrial Hyperplasia/Mucometra

Canine Pyometra: A Short Review of Current Advances

Pyometra, characterized by the accumulation of purulent exudate in the uterus, is the most prevalent reproductive disease in canines. While the disease often begins with mild local symptoms, it can escalate into peritonitis, sepsis, and multi-organ dysfunction, thereby posing a significant threat to life. Despite the high incidence and recognized significance of canine pyometra, gaps persist in our understanding of its epidemiology, etiology, and pathogenesis. Recent studies have, however, broadened our comprehension of this disease, shedding light on potential new infection sources, etiologies, and the application of clinical predictive biomarkers and new therapeutic protocols. This study aimed to review the current understanding of canine pyometra, with particular emphasis on the latest research concerning its etiology and epidemiology. Furthermore, it addressed key research questions and proposed directions for future investigations into various facets of canine pyometra.

The assessment of haematologic and serum chemistry parameters in canine pyometra: a systematic review and meta-analysis

OBJECTIVES

Pyometra is common in non-spayed adult female dogs requiring early diagnosis and treatment to increase the survival rate. The diagnosis of pyometra is mainly based on clinical examination and anamnesis. Radiography, ultrasonography and laboratory analyses are recommended to support a diagnosis. The aim of this study was to assess blood parameters associated with pyometra by performing a systematic review and meta-analysis.

MATERIALS AND METHODS

The review was conducted in accordance with PRISMA guidelines. A search of three databases (PubMed, Google Scholar and CAB abstracts) was performed in July 2022. Studies providing information about laboratory parameters for both the pyometra group and healthy control group dogs were eligible for inclusion. Data extraction included the first author's name, publication year, country, number of participants in both groups, mean values of selected studies, standard deviation values, and blood parameters. The risk of bias for each study was evaluated, and a random-effects meta-analysis was performed.

RESULTS

We included 44 studies which investigated 12 blood parameters. High heterogeneity was detected in all parameters in these meta-analyses. The following blood parameters were increased in dogs with pyometra: white blood cell (mean=27.75×109  L-1 , mean difference (MD)=17.16, 95% confidence interval (CI) 14.85 to 19.47), monocytes (mean=2.06×1012 /L, MD=1.37, 95% CI 0.99 to 1.74), blood urea nitrogen (mean=41.42 mg/dL MD=18.06, 95% CI 12.26 to 23.85), alkaline phosphatase (mean=212.78 IU/L, MD=137.51, 95% CI 81.81 to 88.62), and aspartate aminotransferase (mean=48.31 IU/L, MD=16.96, 95% CI 10.61 to 23.30). The following parameters were reduced: red blood cell (mean=5.42 1012 /L, MD=-1.37, 95% CI -1.68 to -1.05), haemoglobin (mean=121.20 g/L, MD=-30.57, 95% CI -39.70 to 21.45), albumin (mean=23.71 g/L, MD = -8.16, 95% CI -11.46 to -4.86). Lymphocyte, creatinine, urea, and alanine transaminase parameters were increased in some studies and decreased in others.

CLINICAL SIGNIFICANCE

In canine pyometra, some blood parameters are consistently increased, some consistently decreased, and some increased or decreased depending on the study.

Analysis of the concentrations of some haematological parameters, C-reactive protein and anti-Müllerian hormone in bitches affected by pyometra

The work was aimed to research into the vital signs, haematological and biochemical parameters, acute-phase protein concentrations (CRP, albumin), progesterone (PG) and anti-Müllerian hormone (AMH) concentrations in bitches with pyometra and their comparison with those in healthy bitches. In addition, the goal of this work was to assess if some of the tested parameters may be used as a biomarker in the diagnostics of pyometra and the monitoring of the postoperative recovery. Forty 3-6-year-old bitches of various breeds were included in the research and allotted to two groups: the control (C, n = 20) and the diseased - bitches diagnosed with pyometra (P, n = 20). Blood samples for the analyses were taken immediately before surgery (0 h), and 12 h, 24 h, 48 h and 72 h after, excepting for AMH and PG concentrations, which were determined only at 0 h. Clinical examination detected significantly higher respiration rates in bitches with pyometra in comparison to healthy ones at all time points, higher heart rates before and 12 h after surgery, and higher body temperature before and 12 h, 48 h and 72 h post operation (p < .01). Significantly higher concentrations of CRP (p < .01) and lower concentrations of albumin were detected in bitches with pyometra in comparison to their healthy counterparts at all time points. Progesterone and AMH concentration analysis immediately before surgery detected significantly higher levels of the hormone in bitches with pyometra than in the control (p < .01). The inflammatory reaction of the endometrium resulted in a significant AMH concentration increase, whilst increased CRP concentrations and lower albumin concentrations throughout the research may be used as biomarkers of proinflammatory activities, that is of the acute-phase response.

Effect of systemic inflammatory response syndrome (SIRS) on prostaglandin metabolite and oxidative stress in canine pyometra

Pyometra, either open or closed cervix, inevitably progresses to systemic inflammatory response syndrome (SIRS), if ovariohysterectomy is not done timely. The aim of the study was to investigate the effect of pyometra led SIRS on certain serum biochemical and prostaglandin metabolite, 13,14-dihydro-15-keto PGF2 alpha (PGFM) and oxidative stress indices in the canine. The pyometra positive bitches were categorized as SIRS+ (n=29) and SIRS- (n =16) based on temperature (<100.5 or >102.5°F), respiration rate (>20/min), heart rate (>102/min), and total leukocytes count (<6×103 or >16×103 per μL). The SIRS+ bitches showed hypoalbuminemia, hyperglobulinemia, elevated blood urea nitrogen and creatinine, decreased super oxide dismutase (SOD) activity with moderate increase in the lipid peroxidation. Further, the SIRS+ bitches had significantly higher serum PGFM concentration (6.83±0.7 vs. 4.12±0.4 ng/mL) than SIRS- and the level was influenced by cervical patency. It was concluded that elevated serum PGFM along with hyperglobunemia, blood urea nitrogen, creatinine would be useful in diagnosis and monitoring of pyometra led SIRS in bitch.

Whole genome sequencing for the investigation of canine mammary tumor inheritance - an initial assessment of high-risk breast cancer genes reveal BRCA2 and STK11 variants potentially associated with risk in purebred dogs

Background

Although, in general, cancer is considered a multifactorial disease, clustering of particular cancers in pedigrees suggests a genetic predisposition and could explain why some dog breeds appear to have an increased risk of certain cancers. To our knowledge, there have been no published reports of whole genome sequencing to investigate inherited canine mammary tumor (CMT) risk, and with little known about CMT genetic susceptibility, we carried out whole genome sequencing on 14 purebred dogs diagnosed with mammary tumors from four breed-specific pedigrees. Following sequencing, each dog’s data was processed through a bioinformatics pipeline. This initial report highlights variants in orthologs of human breast cancer susceptibility genes.

Results

The overall whole genome and exome coverage averages were 26.0X and 25.6X, respectively, with 96.1% of the genome and 96.7% of the exome covered at least 10X. Of the average 7.9 million variants per dog, initial analyses involved surveying variants in orthologs of human breast cancer susceptibility genes, BRCA1, BRCA2, CDH1, PTEN, STK11, and TP53, and identified 19 unique coding variants that were validated through PCR and Sanger sequencing. Statistical analyses identified variants in BRCA2 and STK11 that appear to be associated with CMT, and breed-specific analyses revealed the breeds at the highest risk. Several additional BRCA2 variants showed trends toward significance, but have conflicting interpretations of pathogenicity, and correspond to variants of unknown significance in humans, which require further investigation. Variants in other genes were noted but did not appear to be associated with disease.

Conclusions

Whole genome sequencing proves to be an effective method to elucidate risk of CMT. Risk variants in orthologs of human breast cancer susceptibility genes have been identified. Ultimately, these whole genome sequencing efforts have provided a plethora of data that can also be assessed for novel discovery and have the potential to lead to breakthroughs in canine and human research through comparative analyses.

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.

Sterile Pyometra in Two Dogs

Two young dogs were referred to the Veterinary Medical Teaching Hospital of Konkuk University, one for examination of vaginal discharge and the other after being hit by a car. Dog 1 exhibited a high neutrophil count on Gram-stained vaginal smears, marked leukocytosis on a complete blood count, and uterine enlargement on ultrasonography. In dog 2, a markedly enlarged right uterine horn containing echogenic debris was found incidentally on ultrasonography. A tentative diagnosis of pyometra was made in both cases and ovariohysterectomy was performed. Purulent material was collected from each uterine horn and submitted separately for aerobic and anaerobic bacterial culture; all culture results were negative. The white blood cell count revealed normal limits 2 days post operation in dog 1 and 4 days post operation in dog 2. Positive bacterial cultures are usually obtained from dogs with pyometra, and antibiotic selection is based on the results of culture and sensitivity testing in the event of failure of empiric antibiotic therapy. However, in the cases reported here, no bacterial growth was identified from the uterine samples despite the presence of purulent material. A short course of empiric antibiotic therapy was administered. This is the first known report describing sterile pyometra in dogs.