The eye is a sensitive target of sublethal stress in aquaculture-reared fish due to its direct exposure to the aquatic environment. This study tested a photoelectrocatalytic (PEC) water treatment system, integrated into a standard recirculating aquaculture system (RAS), to improve water quality and evaluated ocular health in Oncorhynchus mykiss (rainbow trout) reared at 30 kg/m³ for 28 days, with particular emphasis on the cornea as an indicator of fish welfare. Ocular analyses focused on the cornea and retina, two anatomically and functionally distinct structures. PEC significantly reduced ammonia levels and modulated nitrate concentrations compared to the control group (CTR), represented by a standard RAS. No differences in growth performance or body condition were observed between groups. Corneal integrity was assessed using optical coherence tomography, histology, and mucous cell staining to evaluate epithelial structure and protective responses. Corneal tissue was examined to detect local oxidative effects through morphological analysis and immunohistochemistry for 8-hydroxy-2′-deoxyguanosine (8-OHdG). Alcian Blu–Periodic Acid–Schiff (AB–PAS) staining did not reveal significant differences in mucin-producing cells among groups. CTR fish exhibited epithelial disruption and increased 8-OHdG immunoreactivity, whereas fish reared in the RAS equipped with the PEC system, ensuring improved water quality, showed preserved corneal architecture despite mild oxidative stress. Molecular analysis of ocular tissues revealed no differential expression of oxidative stress-related genes, such as GPx1, GR, or sod1, in the two groups. Overall, these findings support the use of the cornea as a sensitive indicator of sublethal environmental stress in farmed fish and suggest that PEC treatment may contribute to improved water quality management and welfare monitoring in intensive aquaculture systems.

Feline injection-site sarcomas (FISSs) are malignant skin tumors of mesenchymal origin arising at local post-vaccination (or injection) sites. In recent years, a fluorescence imaging technique based on probes targeting α_vβ₃ integrin has been effectively applied for the surgical complete resection of the tumor. In our study, we investigated the utility of a commercially available anti-α_v integrin polyclonal antibody for the histopathological evaluation of FISS’s surgical excision margins. We collected 10 formalin-fixed paraffin-embedded (FFPE) feline excisional biopsies with a histopathological diagnosis of FISS (7 fibrosarcomas and 3 pleomorphic sarcomas) and wide margin tissue, along with one subcutaneous injection-site granuloma and 6 osteosarcomas. Samples were processed for histology, and slides were stained for IHC with the anti-α_v integrin antibody. Immunostained slides were evaluated for the cellular localization and intensity of the staining in different neoplastic and non-neoplastic cell populations. Neoplastic and non-neoplastic spindle cells had cytoplasmic positivity in all fibrosarcomas. Inflammatory cells, including macrophages of the injection-site granuloma, were negative. Multinucleated giant cells in the pleomorphic sarcomas had an intense membranous positivity. Although the anti-α_v integrin antibody was ineffective for the histopathological evaluation of surgical excision margins, the membranous localization of α_v integrin in multinucleated giant cells of pleomorphic sarcomas suggests that it plays a role in the oncogenesis of this FISS variant.

Neoplasia of the cornea is overall rare, with corneal squamous-cell carcinoma (c-SCC) being most commonly reported in all species. C-SCC pathogenesis has been related to UV exposure in humans and horses, and to papillomavirus infection in humans. In dogs, brachycephalic conformation and chronic keratitis were associated with c-SCC. Corneal vascular tumors have also been exceptionally reported in humans, and rarely in animals. In dogs, they have been suggested to be UV-related. Except for equine c-SCCs, most studies on corneal neoplasms are case reports. The present study aimed to review the literature on epithelial and vascular corneal tumors in dogs, cats, and horses, adding new cases from our archives. Pubmed and Web of Science were searched (1980–2025) using the following keywords: cornea, neoplasia, carcinoma, hemangioma, hemangiosarcoma, dog, cat, and horse. Additionally, 94 new cases of corneal neoplasia were retrieved: 47 dogs (40 epithelial and seven vascular); 29 cats (14 epithelial and 15 vascular) and 18 horses. Signalment, clinical history, and histopathological characteristics were analyzed and compared with the literature. The combined results supported a strong association between brachycephalic dogs and c-SCC occurrence and highlighted the frequent coexistence in the feline species of symblepharon and corneal perforation, with corneal tumors.

Aquatic systems throughout the world are increasingly under a wide array of anthropogenic stressors, including the release of a myriad of toxic substances into the environment. The presence of twenty-seven heavy metals, vitamins, and minerals was investigated in muscle tissues collected from 46 wild fishes distributed among Thunnus thynnus (TT), Pagellus bogaraveo, and Dentex dentex (DD) from the Mediterranean Sea. The mean concentration of each element was calculated and compared to the provisional tolerable daily or weekly intake (PTWI) or to the established tolerable upper intake when possible. Specie-specific distribution was documented for the following chemical elements: aluminum (Al), potassium (K), cobalt (Co), molybdenum (Mo), silver (Ag), cadmium (Cd), tin (Sn), and thorium (Th). For the elements without regulated maximum dietary limits, iron (Fe) was highest in TT, while Th was significantly predominant in DD. Several metals were found, often simultaneously, in quantities above the acceptable levels. Specifically, the median concentrations of mercury (Hg) and Cd in the pooled species were significantly higher than their relative PTWI. Significant differences among species were reported for selenium (Se), inorganic arsenic (As), nickel (Ni), and zinc (Zn). Other elements [Al, chromium (Cr), copper (Cu), Sn, lead (Pb), and manganese (Mn)] were found to be at or below the corresponding acceptable levels. The maximum safe consumption calculated for mercury (Hg) leads to advising a limited recommended weekly intake for all the tested Mediterranean Sea fish species.