Transmissible Spongiform Encephalopathies (TSEs) or prion diseases are a fatal group of infectious, inherited and spontaneous neurodegenerative diseases affecting human and animals. They are caused by the conversion of cellular prion protein (PrP^C) into a misfolded pathological isoform (PrP^Sc or prion- proteinaceous infectious particle) that self-propagates by conformational conversion of PrP^C. Yet by an unknown mechanism, PrP^C can fold into different PrP^Sc conformers that may result in different prion strains that display specific disease phenotype (incubation time, clinical signs and lesion profile). Although the pathways for neurodegeneration as well as the involvement of brain inflammation in these diseases are not well understood, the spongiform changes, neuronal loss, gliosis and accumulation of PrP^Sc are the characteristic neuropathological lesions. Scrapie affecting small ruminants was the first identified TSE and has been considered the archetype of prion diseases, though atypical and new animal prion diseases continue to emerge highlighting the importance to investigate the lesion profile in naturally affected animals. In this report, we review the neuropathology and the neuroinflammation of animal prion diseases in natural hosts from scrapie, going through the zoonotic bovine spongiform encephalopathy (BSE), the chronic wasting disease (CWD) to the newly identified camel prion disease (CPD).

Background: Due to the limited information and lack of studies on neoplasms in domestic ruminants, i.e., cattle, sheep, and goats, and domestic swine, the objective of the present study was to systematically review the scientific literature to verify the occurrence, type, organ system, and organs most affected by neoplasms in these animals. Methods: The recommendations of the PRISMA methodology were followed for the elaboration of this study. The research consisted of a systematic review of neoplasms in domestic cattle, sheep, goats, and swine. Results: The number of neoplasms found was 1873. The most affected organ system was the integumentary system with 35.0%, followed in descending order by the alimentary system with 16.90%, the hematopoietic system with 13.50%, the special senses (i.e., eyes and ears) with 10.51%, the female and male genital systems with 7.31%, the urinary system with 4.38%, the liver and biliary system with 3.152%, the endocrine glands with 3.91%, the respiratory system with 2.67%, the nervous system with 2.35%, bones and joints with 0.43%, muscles and tendons with 0.37%, the cardiovascular system with 0.21%, and the pancreas with 0.16%. Of the animals with neoplasms studied, cattle were affected in 69.80% of cases, goats in 10.52%, sheep in 10.46%, and swine in 9.18%. In all species, the most frequent neoplasms were squamous cell carcinomas in ruminants, while melanoma was the most frequent in swine. Few studies carried out in slaughterhouses were found, and the existing ones referred to cattle and swine. No data were found on economic losses with carcass condemnation. Conclusions: In view of the above, it is necessary to carry out extensive and detailed studies that provide knowledge about the impact of neoplasms on the production and condemnation of carcasses in domestic cattle, sheep, goats, and swine and the respective risk factors.

Wasting disease in small ruminants is frequently detected at slaughterhouses. The wasting disorder is manifested by the deterioration of the nutritional and physiological state of the animal indicated by thinness, emaciation, and cachexia. Evidence of emaciation and cachexia, alone, are pathological conditions leading to carcass condemnation during an inspection. Several diseases are associated with a wasting condition, including scrapie, pseudotuberculosis, tuberculosis, paratuberculosis, Maedi Visna, and tumor diseases. On the other hand, parasitic diseases, nutrition disorders, exposure or ingestion of toxins, metabolic conditions, inadequate nutrition due to poor teeth, or poor alimentary diet are conditions contributing to poor body condition. Classical and atypical scrapie is naturally occurring transmissible spongiform encephalopathies in small ruminants. The etiological agent for each one is prions. However, each of these scrapie types is epidemiologically, pathologically, and biochemically different. Though atypical scrapie occurs at low incidence, it is consistently prevalent in the small ruminant population. Hence, it is advisable to include differential diagnosis of this disease, from other possibilities, as a cause of wasting conditions detected during meat inspection at the abattoir. This manuscript is a review of the measures in force at the abattoir for scrapie control, focusing on the differential diagnosis of gross lesions related to wasting conditions detected in small ruminants during meat inspection.

Feline mammary carcinoma (FMC) exhibits aggressive behavior, with limited treatment options. Given the relevance of the PD-1/PD-L1/PD-L2 axis in human breast cancer immunotherapy, this study assessed PD-1 and its ligands in rare FMC histotypes (n = 48) using immunohistochemistry on tumor cells (TCs), intratumoral lymphocytes (iTILs), and stromal tumor-infiltrating lymphocytes (sTILs). PD-1 was expressed in 13% of TCs, 85% of iTILs, and 94% of sTILs, while PD-L1 was observed in 46% of TCs, 96% of iTILs, and 100% of sTILs. PD-L2 was expressed in 79% of TCs and 100% of both iTILs and sTILs, with PD-L1/PD-L2 co-expression in 42% of TCs. Higher PD-1 IHC scores in TCs were associated with a less aggressive biological behavior; PD-L1 in iTILs was linked to skin ulceration, whereas PD-L2 in TCs was associated with its absence. Our findings highlight the relevance of the PD-1/PD-L1/PD-L2 immune checkpoint in rare FMC subtypes and support further investigation into checkpoint-blockade therapies.

With the aim of improving animal health and productivity, plants or plant extracts that have antimicrobial, antifungal and antioxidant properties are often used in studies with broilers. The aim of this work was to investigate the effect of Urtica urens in broilers. Ninety male Ross chicks were used, randomly placed in 30 pens (three broilers per pen). The broilers were assigned to three treatment groups: group CT (control) received a basal diet; group UU1 received a basal diet with 1% dried Urtica urens; and group UU2 received a basal diet with 2% dried Urtica urens. Each treatment consisted of two feeds, distributed from day 1 to 15 (starter) and from day 15 to 36 (grower). As a result of this study, broilers in the UU1 treatment group had higher weight on day 15 (p = 0.029) and day 36 (p = 0.014) than those in treatments CT and UU2 and a higher daily weight gain between days 1 and 15 (p = 0.028) and days 1 and 36 (p = 0.014). Broilers in the UU1 and UU2 groups had lower serum HDL cholesterol (88.8 and 88.9 mg/dL, respectively) than the CT (96.1 mg/dL). In conclusion, the use of dried Urtica urens at 1% as an additive in broiler diets may affect growth performance and blood HDL cholesterol.

Canine cutaneous histiocytoma (CCH) represents a significant proportion of dog skin tumours, often manifesting as the most common neoplastic skin condition in young animals. Predominantly affecting dogs under four, these tumours appear primarily as solitary lesions that may regress spontaneously. This study, conducted over five years at the University of Trás-os-Montes e Alto Douro, involved a detailed histopathological and ultrastructural examination of 93 CCH cases. Histologically, these tumours showed distinct patterns of lymphoid infiltration, which contributed to their classification into four groups based on the inflammatory response and histological architecture. Most tumours displayed signs of epidermal invasion and frequent mitotic figures, with necrosis present in over half of the cases. Ultrastructurally, the neoplastic cells were characterised by pleomorphism, abundant organelles, and adherens-type junctions. This study offers significant insights into the pathophysiology and morphological characteristics of CCH, underscoring the importance of detailed histological and ultrastructural analysis in accurately diagnosing and understanding this common canine tumour.