Risk Factors Associated with Lifespan in Pet Dogs Evaluated in Primary Care Veterinary Hospitals

Investigating the Life Expectancy at Birth of Companion Dogs in Portugal Using Official National Registry Data

This study aimed to provide a comprehensive picture of the life expectancy of dogs in Portugal, focusing on the impact of diverse factors including breed, sex, size, and skull shape. The final dataset, gathering data from the national registry database, consisted of 278,116 dogs with confirmed deaths. The mean lifespan at birth for all the dogs was around 8.91 years, with the female dogs tended to have a similar lifespan to male dogs. The analysis of life expectancy at birth for the 20 most common non-Portuguese breeds and 10 Portuguese breeds revealed that Yorkshire Terriers had the highest life expectancy (10.89 years) and French Bulldogs the lowest (6.27 years). Size and cephalic index were found to be influential factors, with large brachycephalic breeds exhibiting shorter life expectancies and smaller, mesocephalic breeds experiencing longer lifespans. Additionally, the cephalic index had a more substantial impact on life expectancy compared to body size. These findings enhance the understanding of the factors influencing canine longevity and aid in developing strategies to improve the health and lifespan of companion dogs.

Genotypic and phenotypic consequences of domestication in dogs

Runs of homozygosity (ROH) are genomic regions that arise when two copies of an identical ancestral haplotype are inherited from parents with a recent common ancestor. In this study, we performed a novel comprehensive analysis to infer genetic diversity among dogs and quantified the association between ROH and non-disease phenotypes. We found distinct patterns of genetic diversity across clades of breed dogs and elevated levels of long ROH, compared to non- domesticated dogs. These high levels of F ROH (inbreeding coefficient) are a consequence of recent inbreeding among domesticated dogs during breed establishment. We identified statistically significant associations between F ROH and height, weight, lifespan, muscled, white head, white chest, furnish, and length of fur. After correcting for population structure, we identified more than 45 genes across the three examined quantitative traits that exceeded the threshold for suggestive significance, indicating significant polygenic inheritance for the complex quantitative phenotypes in dogs.

Differential behavioral aging trajectories according to body size, expected lifespan, and head shape in dogs

The twofold life expectancy difference between dog breeds predicts differential behavioral and cognitive aging patterns between short- and long-lived dogs. To investigate this prediction, we conducted a cross-sectional analysis using survey data from over 15,000 dogs. We examined the effect of expected lifespan and three related factors (body size, head shape, and purebred status) on the age trajectory of various behavioral characteristics and the prevalence of canine cognitive dysfunction (CCD). Our findings reveal that, although age-related decline in most behavioral characteristics began around 10.5 years of age, the proportion of dogs considered "old" by their owners began to increase uniformly around 6 years of age. From the investigated factors, only body size had a systematic, although not gradual, impact on the aging trajectories of all behavioral characteristics. Dogs weighing over 30 kg exhibited an earlier onset of decline by 2-3 years and a slower rate of decline compared to smaller dogs, probably as a byproduct of their faster age-related physical decline. Larger sized dogs also showed a lower prevalence of CCD risk in their oldest age group, whereas smaller-sized dogs, dolichocephalic breeds, and purebreds had a higher CCD risk prevalence. The identification of differential behavioral and cognitive aging trajectories across dog groups, and the observed associations between body size and the onset, rate, and degree of cognitive decline in dogs have significant translational implications for human aging research, providing valuable insights into the interplay between morphology, physiological ageing, and cognitive decline, and unravelling the trade-off between longevity and relative healthspan.

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.

Dog size and patterns of disease history across the canine age spectrum: Results from the Dog Aging Project

Age in dogs is associated with the risk of many diseases, and canine size is a major factor in that risk. However, the size patterns are complex. While small size dogs tend to live longer, some diseases are more prevalent among small dogs. In this study we seek to quantify how the pattern of disease history varies across the spectrum of dog size, dog age, and their interaction. Utilizing owner-reported data on disease history from a substantial number of companion dogs enrolled in the Dog Aging Project, we investigate how body size, as measured by weight, associates with the lifetime prevalence of a reported condition and its pattern across age for various disease categories. We found significant positive associations between dog size and the lifetime prevalence of skin, bone/orthopedic, gastrointestinal, ear/nose/throat, cancer/tumor, brain/neurologic, endocrine, and infectious diseases. Similarly, dog size was negatively associated with lifetime prevalence of ocular, cardiac, liver/pancreas, and respiratory disease categories. Kidney/urinary disease prevalence did not vary by size. We also found that the association between age and lifetime disease prevalence varied by dog size for many conditions including ocular, cardiac, orthopedic, ear/nose/throat, and cancer. Controlling for sex, purebred vs. mixed-breed status, and geographic region made little difference in all disease categories we studied. Our results align with the reduced lifespan in larger dogs for most of the disease categories and suggest potential avenues for further examination.

Quantifying refractive error in companion dogs with and without nuclear sclerosis: 229 eyes from 118 dogs

OBJECTIVE

To evaluate the relationship between nuclear sclerosis (NS) and refractive error in companion dogs.

ANIMALS STUDIED

One hundred and eighteen companion dogs.

PROCEDURES

Dogs were examined and found to be free of significant ocular abnormalities aside from NS. NS was graded from 0 (absent) to 3 (severe) using a scale developed by the investigators. Manual refraction was performed. The effect of NS grade on refractive error was measured using a linear mixed effects analysis adjusted for age. The proportion of eyes with >1.5 D myopia in each NS grade was evaluated using a chi-square test. Visual impairment score (VIS) was obtained for a subset of dogs and compared against age, refractive error, and NS grade.

RESULTS

Age was strongly correlated with NS grade (p < .0001). Age-adjusted analysis of NS grade relative to refraction showed a mild but not statistically significant increase in myopia with increasing NS grade, with eyes with grade 3 NS averaging 0.58-0.88 D greater myopia than eyes without NS. However, the myopia of >1.5 D was documented in 4/58 (6.9%) eyes with grade 0 NS, 12/91 (13.2%) eyes with grade 1 NS, 13/57 (22.8%) eyes with grade 2 NS, and 7/23 (30.4%) eyes with grade 3 NS. Risk of myopia >1.5 D was significantly associated with increasing NS grade (p = .02). VIS was associated weakly with refractive error, moderately with age, and significantly with NS grade.

CONCLUSIONS

NS is associated with visual deficits in some dogs but is only weakly associated with myopia. More work is needed to characterize vision in aging dogs.

Lifetime prevalence of owner-reported medical conditions in the 25 most common dog breeds in the Dog Aging Project pack

Introduction

Large scale data on the prevalence of diverse medical conditions among dog breeds in the United States are sparse. This cross-sectional study sought to estimate the lifetime prevalence of medical conditions among US dogs and to determine whether purebred dogs have higher lifetime prevalence of specific medical conditions compared to mixed-breed dogs.

Methods

Using owner-reported survey data collected through the Dog Aging Project (DAP) Health and Life Experience Survey for 27,541 companion dogs, we identified the 10 most commonly reported medical conditions in each of the 25 most common dog breeds within the DAP cohort. Lifetime prevalence estimates of these medical conditions were compared between mixed-breed and purebred populations. The frequency of dogs for whom no medical conditions were reported was also assessed within each breed and the overall mixed-breed and purebred populations.

Results

A total of 53 medical conditions comprised the top 10 conditions for the 25 most popular breeds. The number of dogs for whom no medical conditions were reported was significantly different (p = 0.002) between purebred (22.3%) and mixed-breed dogs (20.7%). The medical conditions most frequently reported within the top 10 conditions across breeds were dental calculus (in 24 out of 25 breeds), dog bite (23/25), extracted teeth (21/25), osteoarthritis (15/25), and Giardia (15/25).

Discussion

Purebred dogs in the DAP did not show higher lifetime prevalence of medical conditions compared to mixed-breed dogs, and a higher proportion of purebred dogs than mixed-breed dogs had no owner-reported medical conditions. Individual breeds may still show higher lifetime prevalence for specific conditions.

"Is free-roaming a key factor determining lifespan? An epidemiological study on the life expectancy of Turkish companion dogs"

Companion dog lifespan data has exclusively been studied in developed economies. Here we report results from n = 1312 privately owned Turkish companion dogs (Free-roaming and non Free-roaming) from an online survey analyzed through Kaplan-Meier analysis and Cox regression. Median survival time (MST) was 13 years. Most common causes of death were viral infections (n = 126), cancer (n = 60), and cardiovascular disease (n = 36). Desexing (χ2 = 31.6, P = 2E-8), being a mixed breed (χ2 = 6.4, P = 0.01), and regular preventative care (χ2 = 5.3, P = 0.02) significantly increased lifespan. Roaming freely significantly decreased lifespan (χ2 = 19.5, P = 1E-5). Dogs living in duplexes and single-family homes lived longer than dogs living in apartments and houses on acreage (χ2 = 10.5, P = 0.01). Owner income or education levels did not correlate with lifespan. In a Cox model, only desexing (HR = 0.478, P = 0.0006), living in a house on acreage (HR = 2.30, P = 0.0064) and being allowed to roam freely (HR = 1.59, P = 0.041) remained significant. Even though there are studies that contain information about dog demographics and mortality data outside of the western countries, to our knowledge, this is the first study of factors that influence companion dog lifespan in a middle income economy. While much of our findings correlate with those from developed economies, our sample also lets us study the effects of factors not commonly found in developed economies on dog lifespan, such as being allowed to roam freely.

Evaluating instruments for assessing healthspan: a multi-center cross-sectional study on health-related quality of life (HRQL) and frailty in the companion dog

Developing valid tools that assess key determinants of canine healthspan such as frailty and health-related quality of life (HRQL) is essential to characterizing and understanding aging in dogs. Additionally, because the companion dog is an excellent translational model for humans, such tools can be applied to evaluate gerotherapeutics and investigate mechanisms underlying longevity in both dogs and humans. In this multi-center, cross-sectional study, we investigated the use of a clinical questionnaire (Canine Frailty Index; CFI; Banzato et al., 2019) to assess frailty and an owner assessment tool (VetMetrica HRQL) to evaluate HRQL in 451 adult companion dogs. Results demonstrated validity of the tools by confirming expectations that frailty score increases and HRQL scores deteriorate with age. CFI scores were significantly higher (higher frailty) and HRQL scores significantly lower (worse HRQL) in old dogs (≥ 7 years of age) compared to young dogs (≥ 2 and < 6 years of age). Body size (small < 11.3 kg (25 lbs) or large > 22.7 kg (50 lbs)) was not associated with CFI or total HRQL score. However, older, larger dogs showed faster age-related decline in HRQL scores specific to owner-reported activity and comfort. Findings suggest that the clinician-assessed CFI and owner-reported VetMetrica HRQL are useful tools to evaluate two determinants of healthspan in dogs: the accumulation of frailty and the progressive decline in quality of life. Establishing tools that operationalize the assessment of canine healthspan is critical for the advancement of geroscience and the development of gerotherapeutics that benefit both human and veterinary medicine. Graphical summary of the design, results, and conclusions of the study.

Evaluating Disease Patterns of Military Working Dogs in the Republic of Korea: A Retrospective Study

The purpose of this study was to evaluate disease patterns among military working dogs (MWDs) at the Armed Forces Medical Research Institute (AFMRI) to provide basic medical data on Korean MWDs. The medical records of procedures performed at AFMRI between November 2017 and March 2021 were reviewed. Physical examination, diagnostic imaging, and laboratory tests were performed according to the status of each dog. A total of 353 MWDs (215 males and 138 females; mean age, 6 ± 3 years) were analyzed in this study. Among Korean MWDs, gastrointestinal (GI) disorders are the most frequently diagnosed, followed by dental and musculoskeletal disorders. Foreign body (FB) ingestion had the highest prevalence of GI disorders, with the most common FB being a leather collar or leash. General and dental surgeries, including removal of gastric FB and tooth extraction, were routinely performed at the AFMRI. Preventative care focusing on dental disease and FB ingestion may be helpful for effective performance and good quality of life in MWDs, with the regular assessment and prevention of environmental factors that may contribute to behavioral problems such as FB ingestion, coprophagy, and anorexia.

Development and Validation of a Novel Instrument to Capture Companion Dog Mortality Data: The Dog Aging Project End of Life Survey

Objective

The researchers and clinicians within the Dog Aging Project (DAP), a longitudinal cohort study of aging in companion dogs, created and validated a novel survey instrument titled the End of Life Survey (EOLS) to gather owner-reported mortality data about companion dogs.

Sample

Bereaved dog owners who participated in the refinement, face validity assessment, or reliability assessment of the EOLS (n=42) and/or completed the entire survey between January 20 and March 24, 2021 (n=646).

Procedures

The EOLS was created and modified by veterinary health professionals and human gerontology experts using published literature, clinical veterinary experience, previously created DAP surveys, and feedback from a pilot study conducted with bereaved dog owners. The EOLS was subjected to qualitative validation methods and post-hoc free-text analysis to evaluate its ability to thoroughly capture scientifically relevant aspects of companion dogs' death.

Results

The EOLS was well-received with excellent face validity as assessed by dog owners and experts. The EOLS had fair to substantial reliability for the three validation themes: cause of death (kappa = 0.73; 95% CI [0.5-0.95]), perimortem quality of life (kappa = 0.49; 95% CI [0.26-0.73]), and reason for euthanasia (kappa = 0.3; 95% CI [0.08-0.52]) and had no need for any substantial content alterations based on free-text analysis.

Clinical Relevance

The EOLS has proven to be a well-accepted, comprehensive, and valid instrument for capturing owner-reported companion dog mortality data and has the potential to enhance veterinarians' ability to care for the aging dog population by illuminating their understanding of companion dogs' end-of-life experiences.

Life expectancy tables for dogs and cats derived from clinical data

There are few recent and methodologically robust life expectancy (LE) tables for dogs or cats. This study aimed to generate LE tables for these species with clinical records from >1,000 Banfield Pet hospitals in the USA. Using Sullivan's method, LE tables were generated across survey years 2013-2019, by survey year, and for subpopulations defined by sex, adult body size group (purebred dogs only: toy, small, medium, large and giant), and median body condition score (BCS) over life. The deceased population for each survey year comprised animals with a recorded date of death in that year; survivors had no death date in that year and were confirmed living by a veterinary visit in a subsequent year. The dataset totaled 13,292,929 unique dogs and 2,390,078 unique cats. LE at birth (LE_birth) was 12.69 years (95% CI: 12.68-12.70) for all dogs, 12.71 years (12.67-12.76) for mixed-breed dogs, 11.18 years (11.16-11.20) for cats, and 11.12 (11.09-11.14) for mixed-breed cats. LE_birth increased with decreasing dog size group and increasing survey year 2013 to 2018 for all dog size groups and cats. Female dogs and cats had significantly higher LE_birth than males: 12.76 years (12.75-12.77) vs. 12.63 years (12.62-12.64), and 11.68 years (11.65-11.71) vs. 10.72 years (10.68-10.75), respectively. Obese dogs (BCS 5/5) had a significantly lower LE_birth [11.71 years (11.66-11.77)] than overweight dogs (BCS 4/5) [13.14 years (13.12-13.16)] and dogs with ideal BCS 3/5 [13.18 years (13.16-13.19)]. The LE_birth of cats with BCS 4/5 [13.67 years (13.62-13.71)] was significantly higher than cats with BCS 5/5 [12.56 years (12.45-12.66)] or BCS 3/5 [12.18 years (12.14-12.21)]. These LE tables provide valuable information for veterinarians and pet owners and a foundation for research hypotheses, as well as being a stepping-stone to disease-associated LE tables.

Lifetime prevalence of malignant and benign tumors in companion dogs: cross‐sectional analysis of Dog Aging Project (DAP) baseline survey

Although cancer is widely regarded as a major contributor to canine morbidity and mortality, its frequency in companion dogs has only infrequently been characterised. We analysed cross-sectional data from the baseline survey of owners of 27 541 living companion dogs enrolled in the Dog Aging Project as of 31 December 2020 to estimate the lifetime prevalence of malignant and benign tumours and several potentially-associated characteristics. Survey questions elicited information on history of 'cancer or tumors' including organ site and histologic type. Owners reported 819 malignant tumours (56% sited in the skin, muscle or other soft tissue) and 404 benign tumours (69% sited in the skin, muscle or other soft tissue). The lifetime prevalence of malignant tumours (29.7/1000 dogs) was approximately double the lifetime prevalence of benign tumours (14.7/1000 dogs). Lifetime prevalence of both malignant and benign tumours increased with dog age at survey completion. There were no statistically discernable differences in age-adjusted lifetime prevalence of malignant (prevalence ratio (PR) = 0.93 [95% confidence interval (CI) 0.82, 1.07] or benign tumours (PR = 1.10, 95% CI 0.91, 1.34) in mixed vs. purebred dogs. The lifetime prevalence of malignant tumours increased with increasing dog size class; compared to toy and small dogs, the age-adjusted PRs (95% CIs) for medium, standard, large, and giant dogs were 1.65 (1.28, 2.11), 2.92 (2.35, 3.64), 3.67 (2.92, 4.62) and 2.99 (1.23, 4.02), respectively. Similar though less pronounced patterns in relation to dog size class were observed for benign tumours. Ongoing prospective data collection will permit future studies on risk factors for canine tumour incidence.

The effect of inbreeding, body size and morphology on health in dog breeds

Background

Dog breeds are known for their distinctive body shape, size, coat color, head type and behaviors, features that are relatively similar across members of a breed. Unfortunately, dog breeds are also characterized by distinct predispositions to disease. We explored the relationships between inbreeding, morphology and health using genotype based inbreeding estimates, body weight and insurance data for morbidity.

Results

The average inbreeding based on genotype across 227 breeds was F_adj = 0.249 (95% CI 0.235–0.263). There were significant differences in morbidity between breeds with low and high inbreeding (H = 16.49, P = 0.0004). There was also a significant difference in morbidity between brachycephalic breeds and non-brachycephalic breeds (P = 0.0048) and between functionally distinct groups of breeds (H = 14.95 P < 0.0001). Morbidity was modeled using robust regression analysis and both body weight (P < 0.0001) and inbreeding (P = 0.013) were significant (r² = 0.77). Smaller less inbred breeds were healthier than larger more inbred breeds.

Conclusions

In this study, body size and inbreeding along with deleterious morphologies contributed to increases in necessary health care in dogs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40575-021-00111-4.

Prevalence of Reproductive Disorders including Mammary Tumors and Associated Mortality in Female Dogs

Female dogs, especially intact or neutered lately, are at increased risk for reproductive disorders including mammary tumors (MTs). This retrospective study evaluated the prevalence of reproductive pathology and associated mortality in a cohort of female dogs presented at a single veterinary clinic. The medical records of female dogs born in 2000–2003 were reviewed. The study included 599 cases, of which 293 were followed up until death. Causes of death were analyzed according to the spaying status. Among the 599 female dogs, 306 were intact (51%), 50 (8%) had been spayed before 2 years of age (ES, early spaying), and 243 (41%) after 2 years (LS, late spaying). During their lifetime, 79 dogs (13.2%) developed pyometra, and 160 (26.7%) a mammary tumor. Among the 293 dogs with complete follow-up, 103 (35.1%) had at least one MT during their lifetime, of which 53 (51.5%) died of their mammary cancer. Spayed (ES + LS) female dogs had a 4-fold decreased risk of dying from mammary cancer (OR = 0.23, 95% CI 0.11–0.47, p < 0.0001) compared to intact females. In this low-sterilization rate population, MTs developed in 35.1% of female dogs over their lifetime and was the cause of death in half of them.

Dental Problems and Prophylactic Care in Cats-Knowledge and Perceptions among Swedish Cat Owners and Communication by Veterinary Care Staff

Simple Summary

Dental disease has a negative impact on the quality of life and welfare of various species. The most important preventive measures in cats are performed by the cat owners. However, cat owners’ knowledge of dental disease and prevention is unclear. Veterinary care staff are important sources of information to the cat owners, but the type and frequency of information on dental disease prevention given to the owners have not been described. We conducted web-based surveys to investigate owners’ knowledge of and veterinary care staff’s communication of dental problems in cats. Overall, 2/3 of the cat owners knew about dental disease and listed modified eating behaviour, gingivitis, halitosis, pain and dental calculus as the most common signs. Commonly, the source of information was the internet followed by veterinary care staff, and the most known preventive measure was tooth brushing, although a small proportion performed it daily or every second day. Veterinary care staff responded that they always or sometimes informed cat owners about prophylactic dental care, most frequently by oral communication, and tooth brushing was the most common preventive measure recommended. This study indicates that cat owners have the relevant knowledge to support the oral health of cats, but the application of preventive measures needs to increase to promote welfare in cats. In particular, the motivation and practical options for owners of cats who may not tolerate tooth brushing should be considered, and alternative strategies discussed. Veterinary care staff present relevant communication but there is room to develop strategies such as improvement in education and communication.

Abstract

Dental problems are increasingly recognised in cats although many problems are preventable by tooth brushing. However, the knowledge level and preventive measures performed by owners are unclear. Additionally, there is a shortage of information on the communication by veterinary care staff to owners on dental health and prophylaxis in cats. The aim was to describe the knowledge and perceptions among Swedish cat owners and the communication by veterinary care staff on dental problems and prevention in cats. We distributed two electronic surveys; to cat owners and care staff, respectively. Of the cat owners, n = 407, 2/3 stated that they have knowledge about dental disease, listing modified eating behaviour as the most common sign followed by gingivitis, halitosis, pain and dental calculus. The main source of information was the internet followed by veterinary care staff, and 47% of the owners reported that they perform preventive oral health measures. The single most frequently stated preventive measure was tooth brushing, which was applied by 28% of the cat owners but with low frequency (daily n = 15, every second day n = 14). Veterinary care staff, n = 179, reported that they inform (47%) or sometimes inform (42%) cat owners on prophylactic dental care, daily or 3–7 times a week (combined 39%) most frequently by oral communication, with tooth brushing as the most common measure recommended. This study suggests that cat owners have relevant knowledge on dental health in cats, but the performed preventive measures are too infrequent to support good oral health in cats. There is room to develop strategies such as improvement in education and communication to increase welfare in cats. This includes consideration of the motivation and practical options for owners of cats who may not tolerate tooth brushing.

Healthy, Active Aging for People and Dogs

Dogs act as companions who provide us with emotional and physical support. Their shorter lifespans compel us to learn about the challenges and gifts of caring for older individuals. Our companion dogs can be exemplars of healthy or unhealthy aging, and sentinels of environmental factors that might increase or decrease our own healthy lifespan. In recent years, the field of aging has emphasized not just lifespan, but healthspan—the period of healthy, active lifespan. This focus on healthy, active aging is reflected in the World Health Organization's current focus on healthy aging for the next decade and the 2016 Healthy Aging in Action initiative in the US. This paper explores the current research into aging in both people and companion dogs, and in particular, how the relationship between older adults and dogs impacts healthy, active aging for both parties. The human-dog relationship faces many challenges as dogs, and people, age. We discuss potential solutions to these challenges, including suggestions for ways to continue contact with dogs if dog ownership is no longer possible for an older person. Future research directions are outlined in order to encourage the building of a stronger evidence base for the role of dogs in the lives of older adults.

Most Dogs Are Not NATIVE Dogs

Studies of dogs have proliferated among canine scientists, aided in part by the logistical convenience of working with owned animals whose care is handled by others. These pet dogs are unlike most dogs that have lived in contemporary or prehistoric settings. In particular, many of the dogs studied by canine scientists are NATIVE dogs: (1) neutered, (2) alimented, (3) trained, (4) isolated, (5) vaccinated, and (6) engineered. The distinct genotypes and unusual environments of NATIVE dogs stand in contrast to the characteristics of dogs who have adapted to lives in other human communities and settings. For a holistic perspective on the evolution of dogs, it is helpful to study dogs in environments that share features of the settings in which dogs evolved.

Lifespan of companion dogs seen in three independent primary care veterinary clinics in the United States

Background

The privately owned companion dog is an emerging model in comparative medicine, notably because it shares the human environment including its risk factors, is affected by many analogous age-related diseases, receives comparable medical care, and has excellent veterinary medical data available.

Past studies of dog lifespan have used academic, corporate or insurance data. While independent primary care data exist for the UK, none have as of yet been published for the US. This study analyzed data from three independent primary care US veterinary hospitals and identified factors that influence lifespan and mortality in a cohort of n = 20,970 privately owned dogs using Kaplan-Meier survival estimators and Cox Proportional Hazards modelling, including body size as a covariate.

Results

As previously reported, body size was negatively correlated with lifespan. Gonadectomy was associated with a longer lifespan, with the effect being stronger in females than in males. This lifespan advantage was conserved in gonadectomized female dogs that lived to at least ages 5 and 8 years. We did not find significant differences in lifespan between purebred and mixed breed dogs; however, breeds with larger effective population sizes and/or lower inbreeding coefficients had median survival times 3–6 months longer than breeds with smaller effective population sizes or higher inbreeding coefficients, indicating that these measures of genetic diversity may be affecting breed lifespans. We also found that dog breeds belonging to the “Mountain” ancestral group had median survival times that were 3.5–4.6 years shorter than other purebred dog groups, which remained significant even when correcting for body size.

Conclusions

Our findings show that it is possible to obtain and analyze data from independent veterinary clinics in the US, an approach that could be useful for studies of comparative epidemiology under the One Health and One Welfare paradigms. We also show that the lifespan effects of gonadectomy are not identical between the sexes and should be investigated separately by sex in future analyses. More research is needed to further clarify the influence of age at gonadectomy, as well as the factors leading to the observed differences in lifespan in the “Mountain” ancestral group and in dog breeds of varying inbreeding coefficients and effective population sizes.

Desexing Dogs: A Review of the Current Literature

Background: Desexing dogs is promoted for population control, preventative healthcare, and behavior modification. Common methods are orchiectomy and ovariectomy/ovariohysterectomy. GnRH superagonist implants are available in some areas. Alternative methods like vasectomy and salpingectomy/hysterectomy are uncommon. The terminology used to describe desexing is inconsistent and contradictory, showing a need for the adaption of standardized terminology. Population Control: Surprisingly, empirical studies show no effects of desexing on population control in companion and shelter dogs despite desexing being consistently recommended in the literature. There is evidence for a population control effect in free-roaming dogs, where desexing also has benefits on zoonotic disease and bite risk. Population control in free-roaming dogs is mostly correlated with female, not male desexing. Health and Lifespan: Desexing affects numerous disease risks, but studies commonly neglect age at diagnosis and overall lifespan, age being by far the most important risk factor for most diseases. We argue that lifespan is a more important outcome than ultimate cause of death. A beneficial effect of desexing on lifespan is consistently demonstrated in females, while evidence for a beneficial effect in males is inconsistent. Studies are likely biased in desexing being a proxy for better care and desexed dogs having already lived to the age of desexing. Desexing reduces or eliminates common life-limiting diseases of the female reproductive system such as pyometra and mammary tumors, while no analogous effect exists in males. Disease risks increases across sexes and breeds include cruciate ligament rupture, various cancers, and obesity. Urinary incontinence risk is increased in females only. Various other disease risk changes show considerable variability between breeds and sexes. Behavioral Effects: Desexed males show reduced libido, roaming, conspecific mounting, and urinary marking frequency, as well as reduced male dog-directed aggression in a majority of males desexed for behavioral reasons. There is a detrimental effect on the risk and progression of age-related cognitive dysfunction. Desexed dogs may be less likely to cause bite injuries across sexes. The evidence for other effects such as human-directed aggression, human or object mounting, resource guarding, or shyness and anxiety is inconsistent and contradictory. There are few studies specific to females or individual breeds. Conclusions: The evidence for a beneficial effect of desexing is stronger in female than in male dogs; however, there is significant variation between breeds and sexes, and more research is needed to further elucidate these differences and to arrive at individualized evidence-based recommendations for clinical practice.

2019 AAHA Canine Life Stage Guidelines*

The guidelines are an update and extension of the AAHA Canine Life Stage Guidelines published in 2012. A noteworthy change from the earlier guidelines is the division of the dog’s lifespan into five stages (puppy, young adult, mature adult, senior, and end of life) instead of the previous six. This simplified grouping is consistent with how pet owners generally perceive their dog’s maturation and aging process and provides a readily understood basis for an evolving, lifelong healthcare strategy. The guidelines provide the following recommendations for managing 10 health-related factors at each of the first four canine life stages: lifestyle effect on the patient’s safety, zoonotic and human safety risk, behavior, nutrition, parasite control, vaccination, dental health, reproduction, breed-specific conditions, and a baseline diagnostic profile.