The use of the HOMA (Homeostatic Model Assessment) index in veterinary medicine is emerging as a promising and valuable method for evaluating insulin resistance and beta-cell function in companion animals, particularly in dogs and cats. Originally developed for use in human medicine, HOMA enables a minimally invasive assessment of glucose and insulin homeostasis, offering clinicians a practical tool for diagnosing and monitoring diabetes mellitus in animals. Its application in veterinary practice brings several advantages, including cost-effectiveness, ease of use, and the potential for early detection of metabolic disturbances before clinical symptoms appear. Nonetheless, important limitations persist, such as inter-individual variability, the effects of stress and comorbidities on glucose and insulin values, and the absence of standardized, species-specific reference ranges. These factors highlight the need for methodological refinement and the establishment of validated protocols tailored to the unique physiological characteristics of dogs and cats. Despite these challenges, HOMA represents a promising avenue for advancing the understanding of diabetes pathophysiology in veterinary patients. Future longitudinal studies and controlled trials are essential to confirm its reliability and enhance its clinical relevance. With further development, the HOMA index could become an essential tool in improving diagnostic accuracy and optimizing the management of diabetes in companion animal practice.

Interspecies variability in diabetes mellitus (DM) represents a critical challenge for translational medicine, as metabolic pathways, pancreatic architecture, and therapeutic responses differ substantially across animal models. This systematic review, conducted according to PRISMA 2020 guidelines, synthesized evidence from 86 eligible studies published between 2001 and 2025. Comparative data from rodents, dogs, cats, pigs, non-human primates, and humans were analyzed to identify species-specific patterns in insulin secretion, insulin resistance (IR), β-cell dysfunction, microbiota–metabolism interactions, and susceptibility to diabetic complications. Results indicate that spontaneous diabetes in dogs closely mirrors human type 1 diabetes (T1DM), whereas feline obesity-associated diabetes reflects key features of human type 2 diabetes (T2DM). Rodent models remain essential for mechanistic and genetic studies but show limited chronicity and lower predictive fidelity for long-term outcomes. Non-human primates exhibit the highest physiological similarity to humans, especially regarding β-cell structure and incretin response, supporting their role in advanced translational studies. Major limitations included methodological heterogeneity and inconsistent molecular reporting. Integrating spontaneous models with standardized protocols and multi-omics approaches enhances translational relevance and supports more accurate model selection in diabetes research.

Stress is a major influencing behavior, health, and welfare in free-roaming dogs, particularly in environments characterized by unpredictability, social instability, and frequent human interactions. Although research on canine stress responses has expanded considerably, current knowledge remains fragmented across the neurobiological, physiological, and behavioral domains, limiting the development of comprehensive welfare assessment strategies. Importantly, free-roaming and shelter-housed dogs should not be viewed as entirely separate populations, since many shelter dogs originate from free-roaming environments and share similar stress-related experiences. This narrative review provides a comprehensive synthesis of current evidence on stress mechanisms in free-roaming and shelter-housed dogs The literature was explored across major scientific databases, and a total of 69 relevant studies were included. Particular emphasis was placed on the activation and regulation of the hypothalamic–pituitary–adrenal (HPA) axis, associated neuroendocrine alterations, and their behavioral expression. The strengths and limitations of commonly used physiological indicators, including cortisol measured in blood, saliva, feces and hair, were critically examined in relation to their applicability in real-world contexts. Behavioral manifestations of stress, such as fear- and anxiety-related responses, aggression, withdrawal, and stereotypic behaviors, were analyzed as functional outcomes of neurobiological activation and environmental challenges. Environmental stressors typical of shelter conditions as well as the role of human–dog interactions in stress modulation are also discussed. By combining neurobiological, physiological, and behavioral perspectives, this review highlights the importance of multidimensional stress assessment and proposes a conceptual framework linking biological mechanisms with observable behavioral indicators of welfare across the continuum from free-roaming to shelter environments. These findings may support the development of evidence-based welfare assessment and management strategies for free-roaming and shelter-housed dog populations.