In recent years, the COVID-19 pandemic has fundamentally reshaped many aspects of daily life, including the way we care for and interact with our canine companions. A groundbreaking study published on September 10, 2025, in the open-access journal PLOS One presents a comprehensive analysis of the behavioral patterns of 47,444 dogs enrolled in the Dog Aging Project from 2020 to 2023. Spearheaded by researchers Courtney Sexton from Virginia Polytechnic Institute and State University and Yuhuan Li from the University of Washington, this work illuminates how the pandemic’s disruptions may have influenced dog behavior across several key dimensions. By leveraging survey data collected over four consecutive years, the study provides one of the most extensive behavioral baselines of domestic dogs to date, offering not only insights into pandemic-specific phenomena but also a crucial foundation for understanding age-related behavioral shifts over time.
The Dog Aging Project is a pioneering longitudinal research initiative that collects data on thousands of dogs to explore connections between behavior, genetics, environment, and health outcomes throughout their lifespans. Through a large-scale owner-reported survey, the research team cataloged behavioral characteristics across four primary domains—fear, attention, aggression, and trainability. This multidimensional approach aims to capture the nuanced ways dogs respond to their environments, social conditions, and developmental stages. Importantly, the magnitude of the dataset—over 47,000 individual dogs—presents an unprecedented opportunity to examine population-wide behavioral trends as dogs transitioned through the height of the pandemic and entered a world adapting to post-pandemic life.
Notably, one of the study’s principal findings centers on changes in trainability scores reported by owners during the pandemic years. Dogs entering the study in 2020 exhibited higher average trainability, indicating greater responsiveness to commands and tolerance to tactile interactions such as petting. However, this trainability metric showed a marked decline for dogs enrolled in 2021 and 2022, aligning temporally with dynamic societal restrictions and changes in daily routines. The authors suggest this dip may be related to the challenges that owners faced when socializing and training “pandemic puppies,” dogs acquired during lockdown periods with limited external stimuli and interactions. By 2023, however, these scores began to rebound, hinting at a gradual return to more typical training environments and owner expertise as pandemic-related constraints eased.
This longitudinal perspective is particularly valuable because it challenges some assumptions about the pandemic’s behavioral impact. Despite widespread speculation that the upheaval in routines, socialization opportunities, and owner availability would cause dramatic shifts in canine behavior, the study found that overall behavioral profiles remained relatively stable from year to year. While fluctuations in certain traits like aggression and trainability were evident, the broad spectrum of behaviors assessed did not display sweeping alterations. This stability suggests a remarkable degree of behavioral resilience in companion dogs facing environmental and social challenges.
Digging deeper into the dataset, the researchers uncovered intriguing associations between behavioral traits and intrinsic factors such as breed type, age, sex, and body size. Mixed breed dogs were rated by their owners as generally more fearful and exhibiting higher levels of aggression and attentional demands than purebred counterparts. The team hypothesized that this may be attributed to a higher likelihood that mixed breeds were adopted from shelters or rescue situations, potentially exposing them to early-life stress or trauma that influences later behavior. These findings underscore the importance of consideration for individual backgrounds when assessing pet behavior and health.
Age also played a significant role in shaping behavioral characteristics. Puppies were reported to be less fearful and aggressive than older dogs but simultaneously required more attention and scored lower on trainability scales. This pattern reflects developmental stages characterized by heightened dependency and learning needs. Conversely, adult dogs displayed more balanced behavioral traits, emphasizing the dynamic trajectory of canine behavior as dogs mature. These insights contribute to a richer understanding of how behavior evolves naturally in canines, independent of external disruptions such as the pandemic.
Sex-based differences emerged as well. Male dogs tended to be less fearful yet more prone to aggressive behaviors and were perceived as somewhat less trainable compared to females. Such dimorphic behavioral patterns may be influenced by hormonal, genetic, or social factors intrinsic to each sex, with important implications for training and management strategies tailored to individual animals. Furthermore, body size correlated notably with behavioral tendencies: smaller dogs were more likely to be fearful, aggressive, and difficult to train. This outcome may reflect a complex interplay of genetics, owner handling styles, and environmental exposures unique to dogs of differing sizes.
Another compelling finding relates to the reported aggression levels in dogs across the survey years, particularly during the pandemic’s peak. Owners participating in the 2020 survey indicated higher aggression in their pets compared to those who completed the survey in 2023. The authors link this phenomenon to the heightened stress experienced in many households during lockdowns, coupled with reduced opportunities for normal socialization with other dogs and people. Such environmental stressors likely exacerbated anxiety-driven aggressive behaviors, illustrating the profound ways in which human societal shifts can cascade into companion animal welfare.
The methodology underpinning this research—large-scale owner-reported surveys—is itself a noteworthy component that enables continuous, real-world data capture from a broad cross-section of the population. While owner-reports can introduce subjective biases, the volume and consistency of responses over multiple years help mitigate individual variability and permit the detection of generalizable trends. Future iterations of the Dog Aging Project aim to augment these surveys with objective behavioral assessments and biological markers, offering a multidimensional approach to decoding the aging process in dogs.
Crucially, this study establishes a behavioral baseline for tens of thousands of dogs, serving as a reference point from which longitudinal changes can be discerned. The researchers emphasize that by tracking these dogs over time, they will gain novel insights into how behavioral shifts correspond with health outcomes, genetic factors, and environmental influences. Such knowledge could revolutionize veterinary care, training practices, and adoption protocols, ultimately enhancing canine welfare throughout the lifespan.
The findings also provoke important questions about how owners can better support their pets during periods of upheaval or transition. The clear link between pandemic-related stress and behavioral challenges suggests the need for targeted interventions focused on socialization, environmental enrichment, and coping strategies. Veterinarians, trainers, and animal welfare advocates might collaborate to develop resources tailored to times of crisis, ensuring that dogs receive consistent behavioral stimulation and support even when routines are disrupted.
From a broader scientific perspective, this research highlights the value of integrating behavioral science into the study of aging and health. Dogs, as companions who share human environments closely, provide a unique model for exploring the interactions between behavior, environment, and physiology. The continuity offered by the Dog Aging Project’s data will allow scientists to track how early-life behavioral tendencies influence long-term health trajectories, including susceptibility to age-related diseases and cognitive decline.
In summarizing the implications of their work, the authors reflect on the resilience and adaptability of canine behavior even amidst unprecedented global challenges. As they note, the pandemic did not produce drastic changes in dogs’ overall behavioral profiles, emphasizing the robustness of these traits. Yet, subtle shifts in trainability and aggression illuminate how environmental pressures can influence canine behavior in real time. Moving forward, the integration of behavioral data with health outcomes holds promising potential to elucidate how behavioral interventions might promote longevity and quality of life in dogs.
Ultimately, this landmark study opens new frontiers for understanding the complex interplay between dog behavior, environment, and health over time. As the Dog Aging Project continues to follow thousands of enrolled dogs, it will generate insights with profound implications for pet owners, veterinarians, scientists, and the dogs themselves. The nuanced portrait of canine behavior emerging from this research reinforces the critical role that environment, life stage, and individual background play in shaping our most trusted companions’ emotional and cognitive lives.
Subject of Research: Not applicable
Article Title: An analysis of behavioral characteristics and enrollment year variability in 47,444 dogs entering the Dog Aging Project from 2020 to 2023
News Publication Date: 10-Sep-2025
Web References: http://dx.doi.org/10.1371/journal.pone.0330257
References: Li Y, Sexton CL, DAP Consortium, Fitzpatrick A, Ruple A (2025) An analysis of behavioral characteristics and enrollment year variability in 47,444 dogs entering the Dog Aging Project from 2020 to 2023. PLOS One 20(9): e0330257.
Image Credits: Bruce Warrington, Unsplash, CC0
Keywords: Dog behavior, COVID-19 pandemic, trainability, aggression, fear, Dog Aging Project, behavioral survey, canine aging, mixed-breed dogs, pandemic puppies, longitudinal study
