Social determinants of health and disease in companion dogs: a cohort study from the Dog Aging Project

The impacts of household factors and proxies of human social determinants of health on dog behavior

Social determinants of health (SDOH) have an enormous impact on human health and behavior, although their possible effects on canine behavior have received limited scientific attention. The goals of this observational cohort study were to identify associations between canine behavior, household environments, and zip code-level proxies for human SDOH, and to explore longitudinal impacts on behavior. We used an existing dataset of C-BARQ behavioral assessments from 3044 golden retrievers in the United States, including up to eight years of data per dog collected between 2012 and 2023. The data were analyzed using linear mixed effect models and generalized estimating equations. We found dogs from single-dog homes had increased odds of dog-directed fear (OR 1.44, 95 % CI 1.30-1.61) and poorer trainability, particularly during early adulthood (F=14.32, p < 0.001). Sleeping in the owners' bed was associated with increased aggression towards strangers, and a greater reduction in trainability (F=20.71, p < 0.001) and energy with age (F=8.20, p = 0.004). Dogs in the most densely populated neighborhoods had greater odds of showing aggression to strangers compared with dogs in sparsely (OR 0.78, 95 % CI 0.63-0.95) or moderately populated neighborhoods (OR 0.73, 95 % CI 0.60-0.90). Together, our findings illustrate how conspecific relationships, human interactions, home and neighborhood environments affect dog behavior, and show, for the first time, that household characteristics and ownership behaviors have differential impacts on behavior across the lifespan. Future studies including more diverse human and canine populations are needed to provide further insights about the impacts of SDOH on dog health and welfare.

Life expectancy and survival analysis for companion dogs and cats in Seoul, South Korea

Background

Investigating life expectancy and mortality is crucial for the development of evidence-based health strategies for companion animals. However, relevant studies are lacking in South Korea, possibly because of challenges in collecting mortality data. In this regard, preliminary analyses were conducted to obtain life tables for companion animals in South Korea.

Methods

The electronic records of six veterinary hospitals in Seoul, South Korea were examined. The data collected included breed, sex, spay/neuter status, date of birth, and date of death for all dogs and cats with a verifiable date of death since November 1, 2004 until December 31, 2022. After data preprocessing, descriptive statistical analysis was performed to summarize the demographics, and life tables and survival curves were created for dogs and cats. Cox proportional hazards regression was used to analyze the effects of demographic factors on survival.

Results

The mean age of dogs at death was 3427.49 days. Spayed or neutered dogs had a significantly higher life expectancy than intact dogs. Mixed-breed dogs had a higher life expectancy than purebred dogs. For cats, the mean age at death was 1965.49 days, with spayed or neutered cats living significantly longer than intact cats. Purebred cats had a higher median survival than Mixed-breed cats. Spaying or neutering and breed significantly affected survival probabilities in both species.

Conclusion

Our study provides insights into the longevity of companion animals in South Korea, and reveals that neutering and breed significantly influence life expectancy.

Epidemiological and clinical profiles of young and senior dogs fed a standard diet

This study aimed to explore age-related differences in epidemiological and clinical parameters in dogs consuming a standardized diet, focusing on factors relevant to veterinary practitioners. A total of 106 dogs were included, comprising young (2-5 years) and senior (≥8 years) individuals. Epidemiological data were collected through questionnaires and veterinary consultations, while clinical parameters were assessed via physical examinations and blood analyses. Compared to younger dogs, senior dogs were less active, more likely to live in houses, and more frequently received regular deworming. They were also more likely to consume food purchased from pet stores or supermarkets compared to younger dogs. Clinical evaluations revealed that senior dogs had higher plasma globulin and platelets and lower albumin, consistent with chronic low-grade inflammation associated with aging. Muscle loss, poor coat quality, and reduced lymphocyte counts were also prominent in senior dogs, potentially reflecting sarcopenia, malnutrition, and immunosenescence, respectively. Notably, dogs previously fed diets lacking a source of omega-3 fatty acids exhibited elevated plasma triglycerides even after transitioning for four weeks to a premium diet containing fish oil, underscoring the lasting impact of long-term dietary habits. These findings highlight the importance of regular veterinary follow-ups for senior dogs and the role of high-quality nutrition, including sources of omega-3 fatty acids. By identifying key epidemiological and clinical differences, this study offers valuable insights to help veterinary practitioners distinguish between healthy and pathological aging.

Socio-economic assessment of dog population management systems: a scoping review

Introduction

Dog Population Management (DPM) systems primarily aim to reduce the free-roaming dog population, improve the health and welfare of humans and dogs, and foster their peaceful coexistence. A key challenge to resource allocation and evidence-based policy making in DPM is the rare evaluation of the associated socio-economic impacts. This scoping review identifies, maps, and summarizes published parameters and methods on the socio-economic aspect of DPM systems.

Methods

Following PRISMA-ScR guidelines, and with a protocol registered on the Open Science Framework, this review explores (i) types of DPM services, (ii) types of parameters (intervention, impact, monetized, or non-monetized), (iii) methodological approaches (such as cost-benefit or cost-effectiveness analysis), and (iv) gaps and challenges in socio-economic DPM assessments. Relevant publications were identified through a systematic search of PubMed, Embase, Scopus, and Web of Science.

Results

Our review identified 14 out of more than 7,200 studies indicating the limitation of socio-economic data associated with DPM systems. The studies revealed diverse approaches to DPM, sterilization being the most frequently used service, often combined with vaccination and community awareness. Culling was also used by several studies as a DPM intervention, though considered unethical. The review highlighted a range of intervention, impact, and monetary parameters to evaluate the economics of DPM systems, demonstrating the complexity and varied scope of the services. Varied categorizations of the dog population were observed, making comparative evaluation challenging. Economic methods such as cost-benefit and cost-effectiveness analyses were observed, identifying several associated economic metrics. Studies highlighted gaps mostly related to data availability and accessibility.

Conclusion

The limitations of socio-economic data arise from a lack of standardized methodologies across regions and contexts and limited data collection efforts. Prioritizing systematic collection of data on costs, benefits and social impacts allows for a more robust analysis of DPM systems. Developing tools and standardized reporting methods would further facilitate consistent evaluation of impacts, efficient resource allocation and evidence-based policy making to implement the most cost-effective DPM systems.

Systematic review registration

DOI: 10.17605/OSF.IO/NHE3X.

DNA methylation of transposons pattern aging differences across a diverse cohort of dogs from the Dog Aging Project

Within a species, larger individuals often have shorter lives and higher rates of age-related disease. Despite this well-known link, we still know little about underlying age-related epigenetic differences, which could help us better understand inter-individual variation in aging and the etiology, onset, and progression of age-associated disease. Dogs exhibit this negative correlation between size, health, and longevity and thus represent an excellent system in which to test the underlying mechanisms. Here, we quantified genome-wide DNA methylation in a cohort of 864 dogs in the Dog Aging Project. Age strongly patterned the dog epigenome, with the majority (66% of age-associated loci) of regions associating age-related loss of methylation. These age effects were non-randomly distributed in the genome and differed depending on genomic context. We found the LINE1 (long interspersed elements) class of TEs (transposable elements) were the most frequently hypomethylated with age (FDR < 0.05, 40% of all LINE1 regions). This LINE1 pattern differed in magnitude across breeds of different sizes- the largest dogs lost 0.26% more LINE1 methylation per year than the smallest dogs. This suggests that epigenetic regulation of TEs, particularly LINE1s, may contribute to accelerated age and disease phenotypes within a species. Since our study focused on the methylome of immune cells, we looked at LINE1 methylation changes in golden retrievers, a breed highly susceptible to hematopoietic cancers, and found they have accelerated age-related LINE1 hypomethylation compared to other breeds. We also found many of the LINE1s hypomethylated with age are located on the X chromosome and are, when considering X chromosome inactivation, counter-intuitively more methylated in males. These results have revealed the demethylation of LINE1 transposons as a potential driver of intra-species, demographic-dependent aging variation.

Dog Aging: A Comprehensive Review of Molecular, Cellular, and Physiological Processes

The aging process is a multifactorial biological phenomenon starting at birth and persisting throughout life, characterized by a decline in physiological functions and adaptability. This decline results in the diminished capacity of aging organisms to respond to environmental changes and stressors, leading to reduced efficiency in metabolic, immune, and hormonal functions. As behavioral flexibility wanes, older individuals face longer recovery times and increased vulnerability to diseases. While early research proposed nine core hallmarks of mammalian aging, recent studies have expanded this framework to twelve key characteristics: epigenetic changes, genomic instability, telomere shortening, loss of proteostasis, altered metabolism, mitochondrial dysfunction, cellular senescence, disrupted intercellular communication, stem cell depletion, immune system dysfunction, accumulation of toxic metabolites, and dysbiosis. Given the growing interest in the aging area, we propose to add a new hallmark: impaired water homeostasis. This potential hallmark could play a critical role in aging processes and might open new directions for future research in the field. This review enhances our understanding of the physiological aspects of aging in dogs, suggesting new clinical intervention strategies to prevent and control issues that may arise from the pathological degeneration of these hallmarks.

The doodle dilemma: How the physical health of 'Designer-crossbreed' Cockapoo, Labradoodle and Cavapoo dogs' compares to their purebred progenitor breeds

Booming UK ownership of designer-crossbreed dogs resulting from intentional crossing of distinct purebred breeds is often motivated by perceived enhanced health, despite limited evidence supporting a strong 'hybrid vigour' effect in dogs. Improved evidence on the relative health of designer-crossbreed dogs could support prospective owners to make better acquisition decisions when choosing their new dog. This study used a cross-sectional survey of UK owners of three common designer-crossbreeds (Cavapoo, Cockapoo, and Labradoodle) and their progenitor breeds (Cavalier King Charles Spaniel, Cocker Spaniel, Labrador Retriever, and Poodle) to collect owner-reported health disorder information. The authors hypothesised that designer-crossbred breeds have lower odds of common disorders compared to their progenitor breeds. Multivariable analysis accounted for confounding between breeds: dog age, sex, neuter status, and owner age and gender. The odds for the 57 most common disorders were compared across the three designer-crossbreeds with each of their two progenitor breeds (342 comparisons). Valid responses were received for 9,402 dogs. The odds did not differ statistically significantly between the designer-crossbreeds and their relevant progenitor breeds in 86.6% (n = 296) of health comparisons. Designer-crossbreeds had higher odds for 7.0% (n = 24) of disorders studied, and lower odds for 6.4% (n = 22). These findings suggest limited differences in overall health status between the three designer-crossbreeds and their purebred progenitors, challenging widespread beliefs in positive hybrid vigour effects for health in this emerging designer-crossbreed demographic. Equally, the current study did not suggest that designer-crossbreeds have poorer health as has also been purported. Therefore, owners could more appropriately base acquisition decisions between designer-crossbreeds and their purebred progenitors on other factors important to canine welfare such as breeding conditions, temperament, conformation and health of parents.

Social and environmental risk factors for canine leptospirosis: A scoping review

BACKGROUND

Canine leptospirosis is a zoonotic disease of global importance. The identification of social and environmental risk factors remains limited and is needed for planning interventions. Our objectives were to summarise the global trends in social and environmental risk factors for canine leptospirosis and to identify knowledge gaps.

METHODS

We searched peer-reviewed and grey literature for observational studies on canine leptospirosis written in English. Variables assessed via formal statistical tests were recorded and categorised into thematic risk factor groups. The risk factors were summarised by the number of unique studies and their direction of association.

RESULTS

Of the 3184 articles identified, 66 met the inclusion criteria. Eight environmental and three social risk factor groups were identified. Exposure to animals and water was commonly studied, but social risk factors were infrequently examined. Most studies were conducted on populations in higher-income countries and countries in the Americas.

LIMITATIONS

Several limitations were encountered, including inconsistent study designs and measurement and control of variables as well as disproportionate representation of studies from the Americas and higher-income countries.

CONCLUSION

The weight and quality of evidence for social and environmental risk factors were highly variable. Additional research following standard reporting guidelines to improve transparency and increase generalisability to different contexts is needed.

Canine sentinels and our shared exposome

Dogs are distinctly positioned to be indicators of human health and well-being.

Longevity of companion dog breeds: those at risk from early death

The companion dog is one of the most phenotypically diverse species. Variability between breeds extends not only to morphology and aspects of behaviour, but also to longevity. Despite this fact, little research has been devoted to assessing variation in life expectancy between breeds or evaluating the potential for phylogenetic characterisation of longevity. Using a dataset of 584,734 unique dogs located within the UK, including 284,734 deceased, we present variation in longevity estimates within the following: parental lineage (purebred = 1 breed, crossbred ≥ 2 breeds), breed (n = 155), body size (large, medium, small), sex (male, female) and cephalic index (brachycephalic, mesocephalic, dolichocephalic). Survival estimates were then partitioned amongst phylogenetic clades: providing evidence that canine evolutionary history (via domestication and associated artificial selection) is associated with breed lifespan. This information provides evidence to inform discussions regarding pedigree health, whilst helping current/prospective owners, breeders, policy makers, funding bodies and welfare organisations improve decision making regarding canine welfare.