The renin–angiotensin–aldosterone system (RAAS) plays a pivotal role in regulating cardiovascular function, fluid balance, and blood pressure. Recent research has revealed the RAAS’s influence extends beyond cardiovascular physiology, encompassing key roles in inflammation, fibrosis, immune regulation, cancer progression, and organ-specific disease mechanisms. This review provides a comprehensive overview of classical and alternative RAAS pathways, focusing on the dual roles of angiotensin II (Ang II) and angiotensin-(1–7) (Ang 1–7), mediated through AT1R, AT2R, MasR, and MrgD receptors. We discuss molecular signaling cascades, including mitochondrial, nuclear, and caveolae-mediated mechanisms, and explore the impact of RAAS modulation on hepatic fibrosis, vascular remodeling, and autoimmune inflammation. Genetic models and emerging pharmacologic strategies illustrate tissue-specific RAAS actions, emphasizing the therapeutic potential of enhancing the ACE2/Ang 1–7/Mas axis while inhibiting the deleterious ACE/Ang II/AT1R signaling. Furthermore, we highlight implications for veterinary medicine, particularly in canine chronic inflammatory enteropathies, where RAAS dysfunction may contribute to treatment resistance. Understanding RAAS complexity and inter-receptor crosstalk is essential for developing new therapeutic strategies targeting cardiovascular, hepatic, and inflammatory diseases in both human and veterinary contexts.

In the poultry industry, measures related to combating antimicrobial resistance have accelerated the search for safe and effective alternatives capable of sustaining production while limiting the spread of pathogens in livestock farms. Among these, postbiotics have recently emerged as a promising solution to overcome the use of traditional in-feed additives. Defined as a preparation of inanimate microorganisms and/or their components that confer a health benefit to the host, postbiotics appear to combine biological effects with improved technological stability. Numerous studies have highlighted their beneficial effects on gut morphology, mucus production, immune modulation, microbiota composition and feed conversion ratio. Moreover, several postbiotic formulations exhibit protective effects against pathogens, suggesting a potential role in disease prevention. Overall, current evidence indicates that postbiotics are a valuable tool for improving poultry health, productivity and food safety while reducing reliance on antibiotics. This review summarises the studies on the use of postbiotics in poultry, providing a framework for their documented benefits. It also aims to highlight the limitations associated with their application and the existing knowledge gaps—particularly regarding mechanisms of action, optimal dosages, and methods of administration—in order to support standardisation and ensure reproducibility within the livestock industry.

The interest for in ovo feeding has grown in the last decades mainly concerning probiotics, live microorganisms that can actively interact with the embryo. The aim of this study was to evaluate the effects of a multi-strain probiotic diluted in Marek’s disease vaccine (MDV) on zootechnical performances, intestinal morphology and Eimeria spp. infection. One hundred and twenty eggs of Ross 308 broiler chickens were incubated until 18 d, when 105 fertilised and vital eggs were randomly allocated into three groups. A control group (C) was inoculated with MDV; two treated groups (P1 and P2) were inoculated with MDV and different concentrations of probiotics: 1 × 10⁵ CFU/100 μL in P1 and 1 × 10⁶ CFU/100 μL in P2. After hatching, chickens were separated into three replicates (10/replicate). Zootechnical parameters were determined. At the end of the cycle (35 d), chickens were slaughtered, and the intestine was collected for morphological analysis from nine chickens per group (three/replicate). Eimeria spp. oocyst shedding was determined weekly, and parasitic lesions were analysed on the histological sample. In ovo treatment with probiotic did not influence hatching rate but significantly improved body weight and positively influenced intestinal morphometric data compared to C. Oocyst shedding in faeces resulted in an increase in C, with significant differences at sampling performed at 14, 21 and 28 d of age. These results suggest that the tested probiotic compound is safe for in ovo supplementation and effectively improves zootechnical performances and coccidian resistance.

The yolk sac (YS) plays a pivotal role in avian embryonic development, contributing to both haematopoiesis and immune maturation. This study aimed to evaluate the effects of in ovo administration of a commercial probiotic blend (Slab51^®) on YS cellular dynamics in chicken embryos. At embryonic day (ED) 18, Ross308 broiler eggs were injected with either the probiotic suspension (P) or sterile saline solution (C). YS tissues were sampled at 8, 12, 24 and 36 h post-inoculation for histological and immunohistochemical analysis. Probiotic-treated embryos exhibited a significant reduction in granulocytic foci within the YS, potentially reflecting enhanced peripheral migration of mature granulocytes. Concurrently, a progressive increase in Iba-1+ macrophages was observed in the probiotic group, suggesting accelerated macrophage differentiation. Immunophenotyping revealed a predominance of M1-iNOS+ macrophages across all timepoints, although a significant increase in M2-CD204+ macrophages was detected at 36 h in probiotic-treated embryos, indicating a possible anti-inflammatory shift. Furthermore, a marked increase in CD31+ endothelial cells in the probiotic group supports an associated rise in neo-angiogenesis. These findings suggest that in ovo probiotic administration modulates the YS microenvironment by promoting early macrophage recruitment, macrophage polarization and vascular remodeling. To our knowledge, this is the first report to demonstrate probiotic-induced structural and immunological alterations in the chicken embryo YS. These results provide novel insights into the early immunomodulatory effects of probiotics and highlight the potential of the YS as a key mediator of host–probiotic interaction during embryogenesis.

Oral cavity lesions in sea turtles, particularly Caretta caretta, are relatively rare, and are typically linked to infectious agents as well as anthropogenic factors, including ingestion of marine debris or fishing gear. This report describes a juvenile Caretta caretta found in the northern Adriatic Sea with severe oral lesions affecting the choanae, alimentary tract, and larynx. A comprehensive clinical and histopathological evaluation was conducted, which revealed traumatic injuries caused by the ingestion of a polychaete, Laetmonice cf. hystrix. Mucosal biopsies in the areas of spine penetration revealed the presence of strong sub-epithelial inflammation, characterised by micro-abscesses. In addition, around some fragments of spines, the formation of microgranulomatous lesions with a tendency to encapsulation was observed. Treatment protocol involved the removal of embedded spines and administration of a broad-spectrum antibiotic to prevent secondary infections. Recently, the detection in polychaetes of the aetiological agents of two newly emerging diseases of shrimps, suggests that these worms can be a host or/and passive carrier of these pathogens. This case study underscores the necessity to consider both biological and anthropogenic factors in diagnosing and managing oral lesions in marine turtles. Furthermore, it draws attention to the ecological risks posed by interactions between sea turtles and benthic organisms.