Clinical symptoms
According to the clinical investigation, 30 dogs presented with varying degrees of clinical manifestations at the time of treatment, including depression, loss of appetite, fever, thirst and greed, polyuria, abnormal vulvar secretions, increased abdominal circumference, gastrointestinal disorders and other signs. Among them, 70% had an open cervix and 30% had a closed cervix. The dogs with a closed cervix had a poor presentation condition.
Ultrasonography
Figures 1A and 1B are typical B-ultrasound-confirmed image maps in this case collection[23]. The uterine horns were significantly dilated, and dark regions (shown by white arrows) were observed in the uterine cavity, suggesting uterine fluid. In panel 1A, the uterine wall was significantly hyperplastic and thickened (shown by red arrows), and the free side of the endometrium was wrinkled in appearance. In Figure 1B, the dark areas in the uterine cavity account for a relatively large area, and the uterine wall is significantly thinned (shown by the red arrow) .
Endo/Myo Ratio
Based on the clinical presentation, each of the 40 cases was divided into one of two groups, those with clinical endometritis and those that were healthy. Through the measurement of the Endo/Myo ratio, it was observed that the ratio of all cases in this test was within the parameters described by DeBosschere et al. Therefore, the two groups of patients were further classified anatomical, pathological and hematological diagnosis. For the no clinical signs group (healthy class, Endo/Myo ratio was 0.753 ± 0.044, n = 7; endometrial hyperplasia class, Endo/Myo ratio was 1.057 ± 0.048, n = 3) and clinical signs group (no inflammation, Endo/Myo ratio was 1.057 ± 0.048, n = 1; mild inflammatory infiltration, Endo/Myo ratio was 0.940 ± 0.172, n = 9; proliferative severe inflammatory infiltration, Endo/Myo ratio was 1.255 ± 0.234, n = 12; atrophic severe inflammatory infiltration, Endo/Myo ratio was 0.474 ± 0.146, n = 8).
Gross pathological examination
In Figure 2A, an example of a healthy uterus from this study is presented, the appearance of uterine tissue is small, the uterine horns have a uniform diameter, no bulging, a smooth endometrial surface, and a healthy pink color. Figure 2B shows an uterus with endometrial hyperplasia and a small uniform diameter with no apparent bulging appearance of the uterine horn. The uterine wall was smooth with normal coloration, and there was no endometrial proliferative lesions were observed in the uterine wall. These observations were not significantly different from that of the healthy uterus at the gross observation level.
Figure 2C shows an inflammation-free uterus, and such cases originate from affected dogs with abnormal secretions from the vulva. The uterine horn was bulging slightly, and the uterine cavity contained turbid fluid. No obvious lesions were present on the surface of the uterine wall. Figure 2D shows mild inflammatory cells infiltrating the uterus, insignificant uterine horn bulge, less uterine cavity content, darker uterine wall color, and grain obviously. Figure 2E shows a proliferative severe inflammatory infiltrate of the uterus with exposed endometrium, which is covered with transparent or translucent vesicles of different sizes on the endometrial surface, accompanied by many papillary vegetations. Several blood clots were observed attached to the endometrial surface. Figure 2F shows atrophic severe inflammatory infiltration of the uterus, and dissection shows endometrial atrophy in the uterine horn with dark red honeycomb depressions on the surface.
Histopathological examination
Figure 3A shows a representative healthy uterus with intact endometrial epithelium and a typical monolayer columnar epithelial structure on microscopic examination. The number of endometrial lamina propria glands is small with typically sized glands. The glandular epithelial cells are cuboidal, the structure is intact without destruction, and the glands contain an appropriate amount of secretions. The stromal cells in the lamina propria are evenly distributed, devoid of inflammatory cells, and evidence of intrastromal vessels congestion is absent.
Figure 3B represents the characteristic proliferative lesions in the endometrium. The structure of the intimal epithelium was intact, and some glands of lamina propria showed different degrees of dilation. The lamina propria is mostly occupied by both superficial and deep uterine glands, with the area varying greatly between individual glands. Although the glandular dilation was large, the structure was intact, with glandular epithelial cells transitioning slightly from cuboidal to flat, and reduced stromal cell composition.
Figure 3C shows an inflammation-free uterus with mild endometrial atrophy, intact epithelial structure. The lamina propria uterine glands were uniformly distributed, and no significant dilatation was observed. There was a significantly reduced stromal cell composition, and no uterine lesions or inflammatory infiltrates were noted upon microscopic examination. Figure 3D shows mild inflammatory cell infiltration of the uterus, occasional partial detachment of the endometrial epithelium, and flat folds with dilation of the superficial glands of the lamina propria. Marked congestion of blood vessels was observed along with local inflammatory cell infiltration in the stroma. Figure 3E shows a proliferative uterus with severe inflammation. Complete detachment of the endometrial epithelium and extreme dilatation of the lamina propria uterine glands. This resulted in glandular rupture into adjacent glands and infolding into the glandular lumen to form a labyrinthine view. In addition, morphological hypertrophy with vacuolation of glandular epithelial cells was observed. Figure 3F shows atrophic severe inflammatory infiltration of the uterus. Most of the endometrial epithelium is necrotic and detached, and the lamina propria uterine glands are extremely atrophic with inapparent lumen. Stromal cells are reduced, and the entire thickness of the endometrium is covered with a large number of inflammatory cells.
Complete blood count (CBC) value
WBC test results. In the detection of 30 dogs, the proportion of the abnormal total white blood cell count and the abnormal neutrophils were high. In addition, among the indicators with abnormal values, except the number of lymphocytes and eosinophils, the proportion of abnormal increase was greater than the proportion of abnormal decrease. See Table 3 for the variation range and detection value distribution of each indicator.
RBC test results. In the detection of 30 dogs, the number of cases with normal index was more than the number of cases with abnormal index. The highest number of cases had abnormal red blood cell counts. See Table 4 for the variation range and detection value distribution of each indicator.
Expression of the pro-inflammatory cytokines IL-1β, IL-6 and IL-8
Figures 4A, 4B, and 4C show that the mRNA expression levels of IL-1 β, IL-6 and IL-8 in uterine samples with histological features of inflammation were significantly higher than those in healthy uterine tissue samples. Among them, the three genes in the uterine tissue of endometrial proliferative/atrophic severe inflammatory infiltration were significantly increased compared with the other two groups (p < 0.001). Expression of IL-1β and IL-8 genes in the uterine tissues with mild inflammatory infiltration were significantly and extremely significantly increased compared with the healthy group (p < 0.05 and p < 0.01), respectively. In uterine samples with severe inflammatory infiltration, IL-1 β and IL-6 mRNA in the endometrial atrophy type were significantly increased (p < 0.05 and p < 0.001), respectively. Expression levels of IL-8 were not significantly changed.
Pathological classification
After testing the uterine tissues of 10 clinically asymptomatic healthy dams who underwent sterilization, and 30 clinically symptomatic dogs with endometritis in terms of clinical symptoms, imaging examination, hematological examination, and histopathological examination. The disease cases were divided into 2 groups and 4 sub-group classifications, which are outlined in Table 5.