Pseudoplacentational endometrial hyperplasia (PEH) and cystic endometrial hyperplasia (CEH) are both hyperplastic conditions that may occur in the canine uterus during diestrus. CEH can impair fertility, and, although the consequences of PEH are poorly known, this condition is significantly associated with pyometra. The aim of this study was to investigate frequencies of both PEH and CEH in female dogs according to age, size, breed, and breed group. Uteri from 300 female dogs were sampled and processed for histopathologic analyses. Lesions were identified, and frequencies were statistically compared. PEH was significantly more frequent in dogs between 4 and 12 years of age and significantly less frequent in Yorkshires than Shih-tzus, as well as in the breed group that includes Brazilian Terriers and Yorkshires. CEH was significantly more frequent in dogs older than 12 years, but no breed predisposition was observed. The frequency of PEH was significantly higher than that of CEH. The frequency of pyometra in PEH cases was significantly higher than endometritis or uterus without inflammation. This study identified age, breed group, and size as predisposing factors for PEH and further demonstrated the association between this condition and pyometra in dogs.

Background/Objectives: Trained innate immunity refers to the enhanced responsiveness of innate immune cells, particularly macrophages, following exposure to stimuli such as β-glucan or zymosan, enabling improved defense against unrelated pathogens. This phenomenon has been widely investigated to better understand host–pathogen interactions and to support the development of improved infection control strategies. This study evaluated whether these training stimuli could enhance the protective efficacy of attenuated or inactivated vaccine models against Brucella ovis and Listeria monocytogenes infection. Methods: Trained innate immunity was induced in vivo using β-glucan or zymosan, and seven days later mice were vaccinated with attenuated or gamma-irradiated formulations and subsequently challenged with B. ovis or L. monocytogenes. Vaccine-induced protection and immune responses were assessed through multiple experimental approaches. Results: β-glucan significantly reduced bacterial infection in vitro in bone-marrow-derived macrophages and in vivo in target organs compared with zymosan. Although β-glucan did not enhance the efficacy of the attenuated B. ovis ΔabcBA vaccine, it markedly reduced bacterial colonization in mice vaccinated with gamma-irradiated B. ovis. β-glucan also did not improve the efficacy of the gamma-irradiated L. monocytogenes vaccine; however, 50% of the trained and vaccinated mice showed no detectable bacterial recovery. Increasing the number of β-glucan doses negatively affected infection control, suggesting that overstimulation may impair trained immunity. Conclusion: Trained innate immunity enhances the protective effect of inactivated experimental vaccines against B. ovis and L. monocytogenes, while exerting a detrimental influence on the efficacy of a live attenuated B. ovis vaccine model.

Zoonotic infections constitute a major cause of reproductive failure and perinatal mortality in humans and animals. Among the most relevant etiological agents are Listeria monocytogenes , Brucella spp., and Toxoplasma gondii , which, despite distinct biological properties, share the capacity to breach placental defenses, establish intracellular niches, and impair fetal development. This review aims to synthesize current knowledge on the pathological and pathogenic mechanisms underlying fetal and neonatal death associated with these pathogens, with a focus on placental infection, vertical transmission, and tissue injury. The outcome of infection is highly dependent on the gestational stage at exposure: early gestational infection is frequently associated with embryonic loss or resorption, whereas infection in later stages more commonly results in abortion, stillbirth, or congenital disease. Elucidation of these mechanisms is essential for the development of targeted preventive and control strategies for zoonotic reproductive diseases.