Antimicrobial resistance (AMR) presents a growing global threat, driven by widespread antibiotic misuse across human and veterinary medicine. Companion animals, particularly dogs and cats, harbor complex natural microbiota—including skin, mucosal, and gastrointestinal communities—that are essential to their health yet also serve as reservoirs of antibiotic resistance genes (ARGs). These ARGs can spread through horizontal gene transfer (HGT), especially during bacterial imbalances such as endogenous infections or surgical interventions, increasing the risk of difficult-to-treat infections. Documented zoonotic and anthroponotic transmissions of resistant strains such as MRSA, MRSP, and ESBL-producing E. coli highlight the bidirectional nature of ARG flow between animals and humans. This underscores the critical importance of the One Health approach, which promotes interdisciplinary collaboration to monitor, understand, and combat AMR across the human–animal-environment interface. Key mechanisms of ARG dissemination, the role of companion animal microbiota, and real-world examples of resistance transfer between species illustrate the complexity and urgency of addressing AMR. Targeted surveillance, rational antibiotic use, and public awareness are essential to preserving antimicrobial efficacy and safeguarding both human and animal populations.

Hyperthyroidism is considered the most common endocrinopathy in middle-aged and old cats. The increased level of thyroid hormones influences many organs, including the heart. Cardiac functional and structural abnormalities in cats with hyperthyroidism have indeed been previously described. Nonetheless, myocardial vasculature has not been subjected to analysis. Also, no comparison with hypertrophic cardiomyopathy has been previously described. Although it has been shown that clinical alterations resolve after the treatment of hyperthyroidism, no detailed data have been published on the cardiac pathological or histopathological image of field cases of hyperthyroid cats that received pharmacological treatment. The aim of this study was to evaluate the cardiac pathological changes in feline hyperthyroidism and to compare them to alterations present in cardiac hypertrophy due to hypertrophic cardiomyopathy in cats. The study was conducted on 40 feline hearts divided into three groups: 17 hearts from cats suffering from hyperthyroidism, 13 hearts from cats suffering from idiopathic hypertrophic cardiomyopathy and 10 hearts from cats without cardiac or thyroid disease. A detailed pathological and histopathological examination was performed. Cats with hyperthyroidism showed no ventricular wall hypertrophy in contrast to cats with hypertrophic cardiomyopathy. Nonetheless, histological alterations were similarly advanced in both diseases. Moreover, in hyperthyroid cats more prominent vascular alterations were noted. In contrast to hypertrophic cardiomyopathy, the histological changes in hyperthyroid cats involved all ventricular walls and not mainly the left ventricle. Our study showed that despite normal cardiac wall thickness, cats with hyperthyroidism show severe structural changes in the myocardium.

This review comprehensively compares lymphoma in humans and dogs, highlighting the canine model’s utility in translational research. Canine lymphoma (cL), predominantly diffuse large B-cell lymphoma (DLBCL), mirrors human non-Hodgkin’s lymphoma (NHL) in its clinical presentation, including lymphadenopathy, systemic symptoms (e.g., fever, weight loss), and hematological abnormalities. Morphologically, cL and NHL share similarities in DLBCL subtypes (centroblastic, immunoblastic, anaplastic), although some variations exist, such as the presence of macronuclear medium-sized cells in canine polymorphonuclear centroblastic lymphoma, not observed in humans. Canine and human lymphomas share molecular mechanisms, including the activation of key pathways like NF-κB and mTOR, and genetic and epigenetic alterations. The tumor microenvironment influences tumor growth and immune evasion in both species. Both species exhibit similar responses to chemotherapy, primarily CHOP-based protocols, although canine lymphoma often progresses more rapidly, offering advantages for shorter clinical trials. Molecular targeted therapy is emerging as a promising treatment, with human therapies like rituximab and chimeric antigen receptor T-cell therapy showing efficacy, and canine treatments still developing. Epidemiological data reveal overlapping risk factors, including exposure to environmental carcinogens (e.g., household chemicals, pollution) and the potential influence of sex hormones, although the role of sex hormones requires further investigation in canines. While staging systems differ slightly (Lugano modification of Ann Arbor for humans, WHO system for dogs), both consider disease extent and systemic involvement. Prognostic factors, such as lactate dehydrogenase (LDH) levels, are relevant in human NHL but have not shown consistent utility in cL. This study concludes that the spontaneous development of cL in immunocompetent dogs, coupled with its clinical, histological, and therapeutic similarities to human NHL, makes the canine model invaluable for preclinical research, accelerating the development of novel diagnostic tools and therapies for both human and canine lymphoma. The shared environmental risk factors and shorter disease progression in dogs further enhance the translational potential of this model, promoting a One Health approach to cancer research.

Probiotics play a critical role in promoting the health of both humans and animals, with growing interest in the potential of animal-derived strains. Safety and efficacy assessments are crucial, with rigorous testing required to ensure the absence of harmful effects. The health benefits of animal-derived probiotic strains include improved digestion, balanced microbiota, behavioral impact, reduced inflammation, and minimized risk of infections. Probiotics of animal origin show promise as complementary or alternative options to antibiotics, with potential applications in both veterinary and human medicine. While promising, the usage of animal-derived probiotics requires careful evaluation of safety and regulatory aspects. This research underscores their potential for promoting health across species and contributing to future therapeutic approaches.

Recent advancements have significantly enhanced our understanding of the crucial role animal microbiomes play in veterinary medicine. Their importance in the complex intestinal environment spans immune modulation, metabolic homeostasis, and the pathogenesis of chronic diseases. Dysbiosis, a microbial imbalance, can lead to a range of diseases affecting both individual organs and the entire organism. Microbial disruption triggers inflammatory responses in the intestinal mucosa and disturbs immune homeostasis, increasing susceptibility to toxins and their metabolites. These dynamics contribute to the development of intestinal lymphoma, necessitating rigorous investigation into the role of microbiota in tumorigenesis. The principles explored in this study extend beyond veterinary medicine to encompass broader human health concerns. There are remarkable parallels between the subtypes of lymphoproliferative disorders in animals and humans, particularly Hodgkin’s lymphoma and non-Hodgkin’s lymphoma. Understanding the etiology of a cancer of the lymphatic system formation is critical for developing both preventive strategies and therapeutic interventions, with the potential to significantly improve patient outcomes. The aim of this study is to discuss the optimal composition of the microbiome in dogs and cats and the potential alterations in the microbiota during the development of intestinal lesions, particularly intestinal lymphoma. Molecular and cellular analyses are also incorporated to detect inflammatory changes and carcinogenesis. A review of the literature on the connections between the gut microbiome and the development of lymphomas in dogs and cats is presented, along with potential diagnostic approaches for these cancers.

Hypertrophic cardiomyopathy (HCM) is the most frequent type of cardiac disease in cats. Due to its high prevalence and risk of sudden and severe signs, the disease is an important topic of various research. Despite the focus on the clinical course of the disease, studies presenting the pathological and histopathological patterns are rare. The study was conducted as a retrospective analysis of feline patients subjected to postmortem examination in the Cardiopathology Unit due to a clinical diagnosis of hypertrophic cardiomyopathy based on echocardiographic examination and ACVIM guidelines. Thirty-four cats clinically diagnosed with HCM were enrolled in the study. During the postmortem examination, hearts were subjected to gross morphometric and histopathological evaluation. Our results show that the histopathological pattern in cats with clinically stated HCM is very diverse, affecting both ventricles and atria. The histopathological picture is more complex in animals diagnosed earlier and treated for a longer period. Moreover, it is generally unrelated to wall thickness, with only left ventricular fibrosis affecting the thickness of the left ventricular wall. In conclusion, further research combining clinical and pathological results is required to unambiguously determine the histopathological remodelling that takes place in the myocardium of cats with hypertrophic cardiomyopathy.