Defining healthy aging in older dogs and differentiating healthy aging from disease

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.

The Emerging Role of Water Loss in Dog Aging

Aging involves progressive physiological changes, including the dysregulation of water homeostasis, essential for cellular function, neuronal signaling, and musculoskeletal integrity. This review explores the emerging role of water loss as a central and underestimated driver of functional decline in aging, with a focus on the dog, both as a clinically relevant target species and as a model for human aging. Age-related alterations in water metabolism-driven by changes in body composition, aquaporin (AQP) expression, electrolyte imbalances, reduced thirst perception, and impaired urine concentration-lead to intracellular and extracellular dehydration, exacerbating functional decline. We examine molecular mechanisms of water regulation involving AQPs and osmolytes, and describe how dehydration contributes to structural and metabolic dysfunction across key biological compartments, including the kidney, brain, bone, and skeletal muscle. Physiological dehydration, a hallmark of aging, intensifies inflammaging, accelerating tissue degeneration. In particular, we highlight how water loss impairs solvent capacity, solute transport, protein conformation, and cellular communication. Despite the known role of macronutrients in geriatric nutrition, hydration remains an often-overlooked factor in aging management. We argue for its inclusion as a fourth pillar in the nutritional approach to veterinary geriatrics, alongside protein, fat, and fiber. By investigating aging-associated water loss in dogs-species that share environments and lifestyle patterns with humans-we propose hydration-centered strategies to promote healthy aging in both veterinary and comparative medicine.

Cross-sectional and longitudinal analysis of health-related quality of life (HRQoL) in senior and geriatric dogs

Advancements in veterinary medicine have resulted in increased life spans for dogs, necessitating a better understanding of quality of life for older dogs. This study aimed to evaluate quality of life (QoL) progression and its potential association with mortality in senior and geriatric dogs. The Canine Owner-Reported Quality of Life Questionnaire (CORQ), consisting of 17 questions across four domains (vitality, companionship, pain, and mobility) was employed. Higher scores indicated better quality of life, with 7 as the highest potential score for each question. In a cross-sectional analysis including 92 dogs, we found an inverse correlation between overall CORQ (and all domain scores) and fractional lifespan. The domain of vitality demonstrated the lowest scores, while companionship exhibited the highest. A longitudinal analysis, including 34 dogs, revealed that when dogs reach the geriatric stage (100% of their calculated lifespan), their expected overall CORQ is 5.95 out of 7, and dogs are expected to have a monthly decline of 0.05 units in the score. Cox proportional hazard analysis demonstrated a significant association between overall CORQ scores and mortality, with dogs scoring below 5.35 being at a higher risk of mortality. This study underscores the association between aging, declining quality of life, and increased mortality risk in aging dogs.

Prevalence and factors associated with overweight and obesity in dogs presenting to French university veterinary teaching hospitals during the COVID-19 pandemic

Pet obesity is still a major health issue, which is considered an epidemic by some researchers. Prevention is one of the cornerstones of veterinary care, emphasizing the importance of proactive measures. Human lifestyle was affected during the COVID-19 pandemic, resulting in an increased overweight prevalence in the population. The prevalence of overweight and obesity in dogs during this period has been poorly explored. This study's objectives were to assess the percentage of the French dog population with overweight and obesity, compare the results with a study conducted before the COVID-19 pandemic, and investigate any potential changes in the risk factors. The study collected data through a survey completed by dog owners during their pets' vaccination visits at university veterinary hospitals of Maisons-Alfort (Paris) and Toulouse, in France, between 2020 and 2022. The veterinarian recorded the dog's weight and the body condition score using a 9-point scale. The study included a total of 309 dogs. Of these, 1.6 % were underweight, 63.1 % had an ideal body condition, and 35.3 % were overweight, including 2.3 % of all dogs classified as obese. During the pandemic, French dog diets shifted towards increased commercial food consumption and twice-daily feedings compared to a 2003 study. Factors positively associated with overweight were being female (OR = 3.55; 95 % CI: 1.65-8.01; P=0.002), being senior (OR=4.91; 95 % CI: 2.07-12.2; P<0.001) or geriatric (OR=5.81; 95 % CI: 2.04-17.0; P=0.001) and having an owner underestimating dog's body condition (OR=74.1; 95 % CI: 29.8-215; P<0.001). Recognizing the impact of owner perception enables early intervention strategies, such as educating owners during consultations and conducting teaching sessions at the clinic. This proactive approach could contribute to improved health outcomes and help prevent the onset of obesity-related issues in dogs. The new trends in dogs' diets may have global relevance due to the pandemic's widespread impact. Although no immediate impact on overweight is evident, ongoing research is crucial to understand the pandemic's long-term effects.

Cross-sectional United Kingdom surveys demonstrate that owners and veterinary professionals differ in their perceptions of preventive and treatment healthcare needs in ageing dogs

Perceptions of dog owners and veterinary professionals (surgeons/nurses) can influence the preventive healthcare and treatment provided to dogs, especially at the senior life-stage, when chronic diseases become more common. This study compared perceptions of healthcare of dogs as they age between dog owners and veterinary professionals. Data from two online surveys (owners: N = 633, veterinary professionals: N = 305) examined perceived need for veterinary visits and vaccinations. In addition, 48 clinical signs were rated on perceived prevalence (whether owners' dogs had experienced them) and how urgently they should seek veterinary advice. Groups were compared using descriptive statistics and chi-square. Owners most often believed a 'healthy' senior dog (>7 years) should go to the vet once a year (47% owners vs. 25% veterinary professionals, p < 0.001), compared with veterinary professionals every 6 months (39 vs. 73%). A minority (14%) of owners would just take the dog 'if they got sick' but only 2% of veterinary professionals advised this, and 16% of owners of dogs of all ages had not had any contact with their veterinary practise in the previous year. Nearly all veterinary professionals (92%) believed that senior/geriatric dogs should receive yearly vaccinations. However, 28% of owners' dogs of all ages were not vaccinated in the previous year and, of these, 33% did not believe that older dogs need vaccinations. Only 10% of dogs considered 'old' by their owners had attended a senior wellness clinic or examination, despite 14% of practises offering them. The three most common clinical signs reported by owners were slowing down on walks (57%), dental tartar (53%) and being stiff on rising (50%). Owners perceived urgency to seek veterinary care was lower if they had experienced the clinical sign before. In the current study, dog owners and veterinary professionals differed in their opinions about the need for veterinary care, suggesting new educational initiatives, and more effective communication is required.

Cognitive Changes Associated with Aging and Physical Disease in Dogs and Cats

Behavior changes may indicate primary physical disease or primary behavioral disorders in veterinary patients. It is imperative to recognize that secondary behavioral problems can develop due to medical causes. The incidence of systemic disease increases with age and behavior manifestations can be similar to those expected with cognitive dysfunction syndrome. In this article, we review basic concepts of cognition, aging, and cognitive dysfunction syndrome. Additionally, we provide information regarding factors that influence cognition, and the role medical conditions have on the behavior of aging pets.

The Relationship between Signs of Medical Conditions and Cognitive Decline in Senior Dogs

Canine cognitive dysfunction syndrome (CCDS) is a progressive age-related neurodegenerative disorder in dogs. Minimal research has been performed to investigate how clinical signs may be impacted by other medical conditions. A cross-sectional study was performed using the Canine Cognitive Assessment Scale (CCAS) to evaluate cognitive impairment as reported by owners. Owner-reported health-related measures included behaviour changes, the body condition score, and veterinary diagnoses of disease. The responses from 804 dogs in the last 25% of their expected lifespan were analysed. Factors were identified in the owner-reported behavioural signs of disease representing pathologies in four body systems: musculoskeletal-neurological, digestive, metabolic, and dermatological, with the items comprising these factors also compiled into a cumulative measure of health. The results showed a strong correlation between the CCAS score and both the musculoskeletal-neurological factor and the overall cumulative measure of health. Moderate correlations between the CCAS score and the digestive factor and metabolic factor were also observed. The correlation between the dermatological factor and the CCAS score was weak. This study highlights the need to screen dogs for concurrent diseases when using scales to assess cognitive impairment and to monitor dogs who have health conditions, particularly those that are painful, for the onset of cognitive impairment.

A masked, placebo-controlled, randomized clinical trial evaluating safety and the effect on cardiac function of low-dose rapamycin in 17 healthy client-owned dogs

Introduction

Geroscience studies of low-dose rapamycin in laboratory species have identified numerous benefits, including reversing age-related cardiac dysfunction. Cardiovascular benefits have been observed in dogs with 10 weeks of treatment, raising questions about possible benefits and adverse effects of long-term use of low-dose rapamycin. The objectives of this study were to assess the impact of 6 months of low-dose rapamycin on echocardiographic indices of cardiac function in healthy dogs and to document the occurrence of adverse events.

Methods

Seventeen client-owned dogs aged 6-10 years, weighing 18-36 kg, and without significant systemic disease were included in a prospective, randomized, placebo-controlled, masked clinical trial. Low-dose rapamycin (0.025 mg/kg) or placebo was administered three times per week for 6 months. Baseline, 6-month, and 12-month evaluation included physical examination, cardiology examination, and clinicopathology. Three-month evaluation included physical examination and clinicopathology. Owners completed online questionnaires every 2 weeks.

Results

There were no statistically significant differences in echocardiographic parameters between rapamycin and placebo groups at 6 or 12 months. No clinically significant adverse events occurred. In 26.8% of the bi-weekly surveys owners whose dogs received rapamycin reported perceived positive changes in behavior or health, compared to 8.1% in the placebo group (p = 0.04).

Discussion

While no clinically significant change in cardiac function was observed in dogs treated with low-dose rapamycin, the drug was well-tolerated with no significant adverse events.

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.

Examining the differential use of a North American animal poison control call center by veterinarians and the public for dog-related calls

Tele-triage, a subset of telehealth services, is becoming increasingly common, they offer users the ability to receive credible health advice from licensed professionals in the comfort of their own home. In the field of veterinary medicine, tele-triage services have been employed since the early 2000s, but there has been little examination of how these services are used by callers. The objectives of this study were to explore how the use of an animal poison control center (APCC) tele-triage service varied between veterinarians and the public in terms of toxicant type, animal demographics, availability of veterinary services, as well as seasonal and secular trends. Data regarding dog poisoning events were obtained from the APCC of the American Society for the Prevention of Cruelty to Animals’ (ASPCA). We fitted a mixed logistic regression model with random intercepts for county and state and identified associations between caller type and the following: animal characteristics (i.e., age, weight, breed-class), type of toxicant, season, year, and access to veterinary services (i.e., veterinarians per capita in the county of the caller). The model included interaction effects between season and both plant and pesticide toxicants. There was also an interaction between year and access to veterinary care. Further investigations are needed to understand how the novelty of a toxicant and the severity of clinical signs associated with a toxicant predict the type of caller, if pet demographics are associated with the caller based on medical issues or owner attitudes, and how access to veterinary care influences the use of this tele-triage service.

Red blood cells morphology and morphometry in adult, senior, and geriatricians dogs by optical and scanning electron microscopy

Red blood cells (RBC) morphologic evaluation through microscopy optical (OM) and SEM, provides information to forecast, evaluate, and monitor the functioning of many organs. Factors, such aging and diseases affect RBC morphology in both, human and animals. SEM is useful to evaluate RBC morphology, although its use in diagnosis and evaluation in dogs is limited, due to the availability and cost. The aim of this research was to assess the normal RBC morphology in adult, senior and geriatrician dogs, clinically healthy by OM and SEM. In addition to evaluating the age effect, sex, body size, and their interaction on erythrocyte morphometry. To carry out the research 152 blood samples were evaluated from dogs of different sexes and body sizes (small, medium, and large). Three groups were made based on dogs age: group I adults (1-7.9 years old), group II senior (8-11.9 years old), and group III geriatricians (>12 years old). Erythrocyte parameters were evaluated by OM (diameter, height, and axial ratio). Per each dog, the parameters of 20 erythrocytes were measured. A total of 2,600 cells were scanned with the AmScope™ Software scale. In addition, the RBC morphology was evaluated by SEM. Statistical analyses used analysis of variance and a general linear model, which allows the comparison of multiple factors at two or more levels (p < 0.05). The results of this study showed that diameter and height were lower in adult dogs than in senior and geriatrician dogs (p < 0.05). Whereas, sex, body size, and the interaction did not show a significant effect (p > 0.05). Additionally, some images of anisocytosis, polychromasia, and poikilocytosis (echinocytes, acanthocytes, codocytes, spherocytes, stomatocytes, dacryocytes quatrefoil, and elliptocytes) were obtained by OM and SEM. Our study provides information about the morphological and morphometry alterations of adult, senior, and geriatrician dogs RBC. This work contributes to future investigations and the diagnosing diseases, where it is necessary to evaluate the morphology of RBC.

Two valid and reliable tests for monitoring age-related memory performance and neophobia differences in dogs

The prolonged lifespan of companion dogs has resulted in increased behavioural and physical challenges linked to old age. The development of behavioural tests to identify and monitor age-related differences has begun. However, standardised testing requires validation. The present study aimed to assess external validity, interobserver reliability, and test-retest reliability of an indoor test battery for the rapid assessment of age-related behavioural differences in dogs. Two experimenters tested young dogs (N = 20, mean age ± SD = 2.7 ± 0.4 years) and old dogs (N = 18, mean age ± SD = 11.8 ± 1.3 years) in the test battery once and then again after two weeks. Our results found external validity for two subtests out of six. On both test occasions, old dogs committed more errors than young dogs in a memory subtest and showed more object avoidance when encountering a novel object. Interobserver reliability and test-retest reliability was high. We conclude that the Memory and Novel object subtests are valid and reliable for monitoring age-related memory performance and object neophobic differences in dogs.

Parvovirus enteritis and other risk factors associated with persistent gastrointestinal signs in dogs later in life: a retrospective cohort study

Background

Parvoviral enteritis (PE) is a viral gastrointestinal (GI) infection of dogs. Recovery from PE has been associated with persistent GI signs later in life. The objectives of this study were: (i) To determine whether dogs that have recovered from PE (post-parvo dogs) had an increased risk of persistent GI signs compared to uninfected control dogs. (ii) To investigate the lifestyle and clinicopathologic factors that are associated with persistent GI signs in post-parvo dogs.

Methods

A total of 86 post-parvo dogs and 52 age-matched control dogs were enrolled in this retrospective cohort study. Many years after hospitalization for PE, the owners were interviewed about the health and habits of their dogs using a questionnaire. We used generalized linear mixed effects models to test whether parvovirus enteritis and other risk factors are associated with owner-recognized general health problems in all dogs and with owner-recognized persistent GI signs in post-parvo dogs.

Results

The prevalence of persistent GI signs was significantly higher in post-parvo dogs compared to control dogs (57% vs 25%, P < 0.001). Markers of disease severity at the time of hospital admission such as neutropenia, low body temperature (BT), and treatment with an antiemetic medication (metoclopramide) were significant risk factors for persistent GI signs in post-parvo dogs. For example, PE-affected dogs that were hypothermic at hospital admission (BT of 37.2 °C) were 16.6 × more likely to have GI signs later in life compared to hyperthermic dogs (BT of 40.4 °C). The presence of persistent GI signs in post-parvo dogs was a risk factor for health problems in other organ systems.

Conclusions

Parvovirus enteritis is a significant risk factor for persistent GI signs in dogs highlighting the importance of prevention. The risk factors identified in the present study may guide future investigations on the mechanisms that link parvovirus enteritis to chronic health problems in dogs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03187-7.

Canine Geriatric Rehabilitation: Considerations and Strategies for Assessment, Functional Scoring, and Follow Up

Geriatric animals account for half of the pet population in the United States with their numbers increasing annually. Furthermore, a significant percentage of veterinary patients with movement limitations could be grossly categorized as geriatric and living within the end stage of their predicted lifespans. Because mobility is correlated to quality of life and time to death in aging dogs, a major goal in optimizing canine geriatric health is to improve functional movement. Within the geriatric population, identifying disabilities that affect daily living and quality of life may be used by the rehabilitation practitioner to provide stronger prognoses, treatment goals, and outcome measures. Examples of such means are described within this review. In human medicine, the concept of “optimal aging”, or “healthy aging”, has emerged in which inevitable detrimental age-related changes can be minimized or avoided at various levels of physical, mental, emotional, and social health. Both environment and genetics may influence aging. Identifying and improving environmental variables we can control remain a key component in optimizing aging. Furthermore, diagnosing and treating age related comorbidities common to older populations allows for improved quality of life and is often directly or indirectly affecting mobility. Obesity, sarcopenia, and a sedentary lifestyle are a trifecta of age-related morbidity common to both people and dogs. Healthy lifestyle choices including good nutrition and targeted exercise play key roles in reducing this morbidity and improving aging. Disablement models act as essential tools for creating more effective physiotherapy plans in an effort to counter dysfunction and disability. Within these models, functional testing represents a standard and validated means of scoring human geriatric function as well as monitoring response to therapy. Because of the great need in dogs, this review aims to provide a reasonable and testable standardized framework for canine functional scoring. We believe a complete assessment of canine geriatric patients should comprise of identifying environmental variables contributing to health status; diagnosing comorbidities related to disease and aging; and characterizing disability with standardized methods. Only through this process can we construct a comprehensive, reasonable, and targeted rehabilitation plan with appropriate follow up aimed at healthy aging.

Development of infrastructure for a systemic multidisciplinary approach to study aging in retired sled dogs

Canines represent a valuable model for mammalian aging studies as large animals with short lifespans, allowing longitudinal analyses within a reasonable time frame. Moreover, they develop a spectrum of aging-related diseases resembling that of humans, are exposed to similar environments, and have been reasonably well studied in terms of physiology and genetics. To overcome substantial variables that complicate studies of privately-owned household dogs, we have focused on a more uniform population composed of retired Alaskan sled dogs that shared similar lifestyles, including exposure to natural stresses, and are less prone to breed-specific biases than a pure breed population. To reduce variability even further, we have collected a population of 103 retired (8-11 years-old) sled dogs from multiple North American kennels in a specialized research facility named Vaika. Vaika dogs are maintained under standardized conditions with professional veterinary care and participate in a multidisciplinary program to assess the longitudinal dynamics of aging. The established Vaika infrastructure enables periodic gathering of quantitative data reflecting physical, physiological, immunological, neurological, and cognitive decline, as well as monitoring of aging-associated genetic and epigenetic alterations occurring in somatic cells. In addition, we assess the development of age-related diseases such as arthritis and cancer. In-depth data analysis, including artificial intelligence-based approaches, will build a comprehensive, integrated model of canine aging and potentially identify aging biomarkers that will allow use of this model for future testing of antiaging therapies.

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.

Reasons for Exclusion of Apparently Healthy Mature Adult and Senior Dogs From a Clinical Trial

Background: Interventional clinical trials intended to maintain health in aging dogs are unusual and require particular attention to exclusion criteria.

Objectives: To describe reasons for exclusion when a mature adult and senior canine population with normal health status was sought.

Animals: Fifty six companion dogs nominated for a randomized controlled trial (RCT).

Procedures: Exclusions occurred within Stage 1 (S1): owner-provided survey information; Stage 2 (S2): medical records review; and Stage 3 (S3): screening examination and within Owner, Dog, or Other factor categories.

Results: Of 56 nominated dogs, 39 were excluded at S1 (n = 19), S2 (n = 5), and S3 (n = 15), respectively. Dogs were excluded for Owner (n = 4), Dog (n = 27), Other (n = 6), and concurrent (Owner + Dog; n = 2) factors. The most common exclusion period was S1 (n = 19), with weight outside the target range being the most common exclusion factor in that stage (n = 10). Heart murmurs were the second most common exclusion factor (S1: n = 1; S3: n = 5); suspected or confirmed systemic illness was third most common (S1: n = 2; S2: n = 3; S3: n = 2). Among dogs who passed S1 and S2 screening (n = 32), 15 dogs (48%) were excluded at S3, for heart murmur > grade II/VI (n = 5), cardiac arrhythmias (n = 2), and clinicopathologic abnormalities (n = 2).

Conclusions and Clinical Relevance: Dogs nominated for a clinical trial for healthy mature adult and senior dogs were excluded for size, previous diagnoses, and newly discovered cardiac abnormalities. For future interventions in mature adult and senior dogs of normal health status, it is important to define expected age-related abnormalities to ensure that meaningful exclusion criteria are used.

Proportion and risk factors for death by euthanasia in dogs in the UK

The loss of a pet can be particularly distressing for owners, whether the method of death is euthanasia or is unassisted. Using primary-care clinical data, this study aimed to report the demographic and clinical factors associated with euthanasia, relative to unassisted death, in dogs. Method of death (euthanasia or unassisted) and clinical cause of death were extracted from a random sample of 29,865 dogs within the VetCompass Programme from a sampling frame of 905,544 dogs under UK veterinary care in 2016. Multivariable logistic regression modelling was used to evaluate associations between risk factors and method of death. Of the confirmed deaths, 26,676 (89.3%) were euthanased and 2,487 (8.3%) died unassisted. After accounting for confounding factors, 6 grouped-level disorders had higher odds in euthanased dogs (than dogs that died unassisted), using neoplasia as the baseline. The disorders with greatest odds included: poor quality of life (OR 16.28), undesirable behaviour (OR 11.36) and spinal cord disorder (OR 6.00). Breed, larger bodyweight and increasing age were additional risk factors for euthanasia. The results highlight that a large majority of owners will face euthanasia decisions and these findings can support veterinarians and owners to better prepare for such an eventuality.

Dog Welfare, Well-Being and Behavior: Considerations for Selection, Evaluation and Suitability for Animal-Assisted Therapy

Simple Summary

Benefits for humans participating in animal-assisted therapy (AAT) have been long documented; however, welfare considerations for the animal counterparts are still quite non-specific, often relating to more general concerns associated with animal-assisted interventions (AAIs). Providers of AAT have a moral and ethical obligation to extend the “Do No Harm” tenet to the animals with whom they work. Companion animals do not ask or voluntarily sign up to be a part of a therapeutic team and their natural traits of love and sociability can easily be misinterpreted and exploited. This article reviews the current state of animal-assisted interventions; it highlights the lack of sufficient evaluation processes for dogs working with AAT professionals, as well as the risks associated with not protecting the dogs’ welfare. Finally, the authors make recommendations for determining the suitability of specific dogs in the clinical setting and ensuring that the population, environment, and context of the work is amenable to the dogs’ welfare and well-being.

Abstract

Health care and human service providers may include dogs in formal intervention settings to positively impact human physical, cognitive and psychosocial domains. Dogs working within this context are asked to cope with a multitude of variables including settings, populations, activities, and schedules. In this article, the authors highlight how both the preparation and operation of dogs within animal-assisted therapy (AAT) differs from less structured animal-assisted activities (AAA) and more exclusive assistance animal work; the authors highlight the gaps in our knowledge in this regard, and propose an ethically sound framework for pragmatic solutions. This framework also emphasizes the need for good dog welfare to safeguard all participants. If dogs are not properly matched to a job or handler, they may be subjected to unnecessary stress, anxiety, and miscommunication that can lead to disinterest in the work, overt problematic behavioral or health outcomes, or general unsuitability. Such issues can have catastrophic outcomes for the AAT. The authors propose standards for best practices for selection, humane-based preparation and training, and ongoing evaluation to ensure the health, welfare and well-being of dogs working in AAT, which will have concomitant benefits for clients and the professionalism of the field.

Cross-Sectional Age Differences in Canine Personality Traits; Influence of Breed, Sex, Previous Trauma, and Dog Obedience Tasks

The dog has been suggested as a possible model for personality development over the lifespan, however, we know little about how aging may shape their personality or the magnitude of age-related changes. Previously we established that aging influences multiple dog demographics, which could also affect how personality traits change across different age periods. A demographic questionnaire and the Dog Personality Questionnaire were completed for a cross-sectional sample of 1,207 adult dogs living in Hungary (M_age = 7.71, SD = 4.12), split into six different age groups. Results revealed three of the five factors showed significant age effects. Activity/Excitability decreased with age, and whilst Responsiveness to training also decreased, only dogs older than 12 years differed significantly from the other groups. Aggressiveness toward animals showed a quadratic trajectory peaking in dogs aged 6–10 years. The greatest magnitude of age-related change was detected between late senior and geriatric ages, likely caused by compensatory behavioral changes to biological aging and owner attitudes to aging. When the models were re-run including the other explanatory variables, age group was no longer significant for the Responsiveness to training trait. The amount of time spent interacting/playing with the owner partially mediated the relationship between age and this trait, implying that interventions to increase play and training motivation may alleviate the negative effects of aging on dogs' trainability. Fifteen out of 28 explanatory variables were significantly associated with at least one of the five factors [weight, breed (pure/mixed breed), sex, off-leash activity, diet, previous trauma, age of dog when arrived in the household, play, dog training activities, number of known commands and dog obedience tasks]. Similarly to humans, dogs that had previously experienced trauma scored higher in fearfulness and aggression. A higher level of basic obedience was linked to some desirable dog personality traits (lower Fearfulness and Aggression, and higher Activity/Excitability and Responsiveness to training). Regardless of the direction of this relationship, obedience is an important aspect contributing to dog personality questionnaires and the dog-owner relationship. This study is unique in that it considered a wide variety of demographic variables which are influenced by aging.

Considerations for the Retirement of Therapy Animals

With the growth of animal-assisted interventions, the number of animals designated to work as therapy animals continues to increase. These animals participate in this work in varying capacities during life, but there will be a point in time when the animal can no longer engage in these activities. The concept of retirement, or withdrawing the animal from its working life, is an important phase of life that every therapy animal will inevitably face. Retirement is typically regarded as a well-deserved reward earned after a lifetime of work, but this termination of an animal's career has potential positive and negative implications for animal, handler, and human participants in these interventions. The question of precisely when and how to appropriately retire an animal is usually answered at the discretion of the handler; however, the validity of this question remains largely unanswered without scientific evidence. The purpose of this review is to describe the implications of therapy animal retirement for the handler, participant, and animal and to discuss the challenges in determining when to retire a therapy animal.

A Frailty Index based on clinical data to quantify mortality risk in dogs

Frailty is defined as a decline in an organism’s physiological reserves resulting in increased vulnerability to stressors. In humans, a single continuous variable, the so-called Frailty Index (FI), can be obtained by multidimensionally assessing the biological complexity of an ageing organism. Here, we evaluate this variability in dogs and compare it to the data available for humans. In dogs, there was a moderate correlation between age and the FI, and the distribution of the FI increased with age. Deficit accumulation was strongly related to mortality. The effect of age, when combined with the FI, was negligible. No sex-related differences were evident. The FI could be considered in epidemiological studies and/or experimental trials to account for the potential confounding effects of the health status of individual dogs. The age-related deficit accumulation reported in dogs is similar to that demonstrated in humans. Therefore, dogs might represent an excellent model for human aging studies.

Tumour, but not Age-associated, Increase of Senescence Markers γH2AX and p21 in the Canine Eye

Senescent cells display an irreversible cell cycle arrest with resistance to apoptosis. They are known to accumulate with age in mice, monkeys and man, and are suspected to drive the development and progression of neoplasia. Eyes develop age-associated changes, most commonly in the retina, cornea and lens. The aim of this study was to test whether senescent cells increase with age in the canine eye in general and in the microenvironment of ocular tumours in particular. The senescence markers γH2AX and p21 were tested in young (n = 10, age ≤2 years) versus old (n = 9, age range 9.5-12.4 years) canine eyes, as well as in the microenvironment of intraocular tumours, namely uveal melanocytomas (n = 13) and ciliary body adenomas (n = 9). To consider a potential association of senescence with biological behaviour, we compared the expression of both markers in tumour cells of benign uveal melanocytomas (n = 13) versus malignant conjunctival melanomas (n = 7). Canine eyes showed no age-dependent changes in senescent cells. However, a significant increase of the percentage of γH2AX- or p21-labelled cells was found in the retina, uvea and lens of tumour-bearing eyes. Tumour cells in conjunctival melanomas had a significantly increased percentage of p21-expressing cells compared with uveal melanocytomas. We conclude, that senescent cells do not accumulate with age in otherwise normal canine eyes and that a senescent microenvironment of intraocular tumours is unlikely to be age driven. In addition, as in man, the percentage of p21-positive cells was increased in melanomas, supporting the theory that malignant tumours may override the senescence-associated cell cycle arrest.

HEMATOLOGY, SERUM BIOCHEMISTRY, AND URINALYSIS VALUES IN THE ADULT GIANT PANDA ( AILUROPODA MELANOLEUCA)

The giant panda ( Ailuropoda melanoleuca) is a high-profile threatened species with individuals in captivity worldwide. As a result of advances in captive animal management and veterinary medicine, the ex situ giant panda population is aging, and improved understanding of age-related changes is necessary. Urine and blood samples were collected in April and July 2015 and analyzed for complete blood count, serum biochemistry, and biochemical and microscopic urine analysis for all individuals sampled ( n = 7, 7-16 yr of age) from giant panda housed at the China Research and Conservation Centre for the Giant Panda in Bifengxia, Sichuan Province, China. Hematology and serum biochemistry values were similar to those previously reported for giant panda aged 2-20 yr and to Species360 (formerly International Species Information System) values. Urine was overall dilute (urine specific gravity range: 1.001-1.021), acellular, and acidic (pH range: 6-7). This is the first report of hematologic and serum biochemistry, with associated urinalysis values, in the giant panda aged 7-16 yr.

Understanding How Dogs Age: Longitudinal Analysis of Markers of Inflammation, Immune Function, and Oxidative Stress

As in human populations, advances in nutrition and veterinary care have led to an increase in the lifespan of companion animals. Detrimental physiological changes occurring later in life must be understood before interventions can be made to slow or reduce them. One important aspect of human aging is upregulation of the inflammatory response and increase in oxidative damage resulting in pathologies linked to chronic inflammation. To determine whether similar processes occur in the aging dog, changes in markers of inflammation and oxidative stress were investigated in 80 Labrador retrievers from adulthood to the end of life. Serum levels of immunoglobulin M (p < .001) and 8-hydroxy-2-deoxyguanosine (p < .001) increased with age, whereas no effect of age was detected for immunoglobulin G or C-reactive protein unless the last year of life was included in the analysis (p = .002). Baseline levels of heat shock protein 70 decreased with age (p < .001) while those after exposure to heat stress were maintained (p = .018). However, when excluding final year of life data, a decline in the heat shock protein 70 response after heat stress was observed (p = .004). These findings indicate that aging dogs undergo changes similar to human inflammaging and offer the possibility of nutritional or pharmacological intervention to delay or reduce these effects.

Paving the Path Toward Retirement for Assistance Animals: Transitioning Lives

Assistance animals play significant roles in human therapy and well-being and represent a rapidly growing demographic of animals in society. Most research in the field of assistance animals has been focused on the effect of these animals on people. Only recently has there been a growing interest in the welfare and well-being of these animals and the effect of the work on the animals themselves. The concept of retirement, or withdrawing the animal from its working life, is an important welfare consideration that has received minimal discussion in the scientific literature. The notion of retirement is typically regarded as a reward earned after a lifetime of work, but this inevitable phase of an animal's working life has positive and negative implications for both animal and handler. Some of these implications include recognizing the emotional impact of this life-altering event on both animal and handler. The decisions of when and how to appropriately retire an animal are typically made at the discretion of the assistance animal agencies and handlers, but standard evidence-based guidelines for the proper retirement of assistance animals are currently unavailable. This review will provide considerations and recommendations for the retirement that assistance animals deserve.

Hematology and biochemistry of aging-evidence of "anemia of the elderly" in old dogs

BACKGROUND

Effects of aging on hematologic and biochemical variables are well described in people. Anemia of the elderly is attributed to iron deficiency, anemia of chronic disease, chronic kidney disease, myelodysplasia, or idiopathic causes. Limited studies have examined these variables in aging dogs, but they have typically examined single breeds in research settings.

OBJECTIVE

The objective of this study was to identify differences in CBC and biochemistry values between adult and aged dogs of many breeds.

METHODS

Dogs presenting for wellness examinations and minor dental/elective surgeries that were otherwise clinically healthy were retrospectively identified. Dogs were categorized by age: adult (1-7.9 years), senior (8-11.9 years), and geriatric (12+ years). Standard CBC and biochemistry data were collated. Asian breeds, Greyhounds, and dogs with data indicating overt underlying disease were excluded. The Kruskal-Wallis test was used to compare groups with statistical significance set at P ≤ .05.

RESULTS

Hematocrit, MCV, and serum iron decreased with age, indicating possible iron-restricted erythropoiesis (IRE), due to iron deficiency or low-grade chronic inflammation. Total proteins, globulins, and platelet counts increased with age while albumin decreased, suggesting low-grade inflammation. Urea was increased in older dogs without a concurrent increase in creatinine, which points toward gastrointestinal bleeding or dehydration.

CONCLUSION

Clinically healthy, aging dogs have changes in laboratory variables that indicate altered physiologies compared to younger adult animals, including evidence of IRE, inflammation, and potential gastrointestinal bleeding, suggesting a similar trend to that of elderly human beings. Future studies will examine markers of iron metabolism and inflammation in aging dogs.

Assessment of frailty in aged dogs

OBJECTIVE To define a frailty-related phenotype-a clinical syndrome associated with the aging process in humans-in aged dogs and to investigate its association with time to death. ANIMALS 116 aged guide dogs. PROCEDURES Dogs underwent a clinical geriatric assessment (CGA) and were followed to either time of death or the study cutoff date. A 5-component clinical definition of a frailty phenotype was derived from clinical items included in a geriatric health evaluation scoresheet completed by veterinarians during the CGA. Univariate (via Kaplan-Meier curves) and multivariate (via Cox proportional hazards models) survival analyses were used to investigate associations of the 5 CGA components with time to death. RESULTS 76 dogs died, and the median time from CGA to death was 4.4 years. Independent of age at the time of CGA, dogs that had ≥ 2 of the 5 components (n = 10) were more likely to die during the follow-up period, compared with those that had 1 or no components (adjusted hazard ratio, 3.9 [95% confidence interval, 1.4 to 10.9]). After further adjustments for subclinical or clinical diseases and routine biomarkers, the adjusted hazard ratio remained significant. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that signs of frailty appeared to be a risk factor for death in dogs. The concept of frailty in dogs requires further development. IMPACT FOR HUMAN MEDICINE The concept of frailty, as defined for humans, seems transposable to dogs. Given that they share humans' environments and develop several age-related diseases similar to those in humans, dogs may be useful for the study of environmental or age-related risk factors for frailty in humans.

Results of Screening of Apparently Healthy Senior and Geriatric Dogs

Background

There is a growing interest in health care of elderly dogs; however, scientific information about physical and laboratory examination findings in this age group is limited.

Objectives

To describe systolic blood pressure (SBP), and results of physical examination and laboratory tests in senior and geriatric dogs that were judged by the owner to be healthy.

Animals

Hundred client‐owned dogs.

Methods

Dogs were prospectively recruited. Owners completed a questionnaire. SBP measurement, physical, orthopedic and neurologic examination, direct fundoscopy and Schirmer tear test were performed. Complete blood count, serum biochemistry, and urinalysis were evaluated.

Results

Forty‐one senior and 59 geriatric dogs were included. Mean SBP was 170 ± 38 mmHg, and 53 dogs had SBP > 160 mmHg. Thirty‐nine animals were overweight. A heart murmur was detected in 22, severe calculus in 21 and 1 or more (sub)cutaneous masses in 56 dogs. Thirty‐two dogs had increased serum creatinine, 29 hypophosphatemia, 27 increased ALP, 25 increased ALT, and 23 leukopenia. Crystalluria, mostly amorphous crystals, was commonly detected (62/96). Overt proteinuria and borderline proteinuria were detected in 13 and 18 of 97 dogs, respectively. Four dogs had a positive urine bacterial culture. Frequency of orthopedic problems, frequency of (sub)cutaneous masses, and platelet count were significantly higher in geriatric compared with senior dogs. Body temperature, hematocrit, serum albumin, and serum total thyroxine concentration were significantly lower in geriatric compared with senior dogs.

Conclusions and Clinical Importance

Physical and laboratory abnormalities are common in apparently healthy elderly dogs. Veterinarians play a key role in implementing health screening and improving health care for elderly pets.

Investigation of risk factors for mortality in aged guide dogs: A retrospective cohort study

The overall median lifespan of domestic dogs has been estimated to 9-12 years, but little is known about risk factors for mortality in aged and a priori healthy dogs. The objective of this retrospective cohort study was to determine which characteristics are associated with mortality in aged and a priori healthy guide dogs, in a retrospective cohort study of 116 guide dogs followed from a systematic geriatric examination at the age of 8-10 years old. A geriatric grid collected the clinical data and usual biological parameters were measured at the time of examination. Univariate (Kaplan-Meier estimates) and multivariable (Cox proportional hazard model) survival analyses were used to assess the associations with time to all-cause death. The majority of dogs were Golden Retrievers (n=48) and Labrador Retrievers (n=27). Median age at geriatric examination was 8.9 years. A total of 76 dogs died during follow-up, leading to a median survival time from geriatric examination of 4.4 years. After adjustment for demographic and biological variables, an increased alanine amionotransferase level (adjusted Hazard Ratio (adjusted HR), 6.2; 95% confidence interval [95%CI], 2.0-19.0; P<0.01), presenting skin nodules (adjusted HR, 1.9; 95% CI, 1.0-3.4; P=0.04), and not being a Labrador Retriever (adjusted HR, 3.3; 95%CI, 1.4-10; P<0.01) were independently associated with a shorter time to death. This study documents independent associations of alanine aminotransferase level, skin nodules and breed with mortality in aged guide dogs. These results may be useful for preventive medical care when conducting a geriatric examination in working dogs.

Exceptional longevity and potential determinants of successful ageing in a cohort of 39 Labrador retrievers: results of a prospective longitudinal study

BACKGROUND

The aim of this study was to describe the longevity and causes of mortality in 39 (12 males, 27 females) pedigree adult neutered Labrador retrievers with a median age of 6.5 years at the start of the study and kept under similar housing and management conditions. Body condition score was maintained between two and four on a 5-point scale by varying food allowances quarterly. The impact of change in body weight (BW) and body composition on longevity was analysed using linear mixed models with random slopes and intercepts.

RESULTS

On 31 July 2014, 10 years after study start, dogs were classified into three lifespan groups: 13 (33 %) Expected (≥9 to ≤12.9 years), 15 (39 %) Long (≥13 to ≤15.5 years) and 11 (28 %) Exceptional (≥15.6 years) with five still alive. Gender and age at neutering were not associated with longevity (P ≥ 0.06). BW increased similarly for all lifespan groups up to age 9, thereafter, from 9 to 13 years, Exceptional dogs gained and Long-lifespan dogs lost weight (P = 0.007). Dual-energy x-ray absorptiometer scans revealed that absolute fat mass increase was slower to age 13 for Long compared with Expected lifespan dogs (P = 0.003) whilst all groups lost a similar amount of absolute lean mass (P > 0.05). Percent fat increase and percent lean loss were slower, whilst the change in fat:lean was smaller, in both the Exceptional and Long lifespan compared with Expected dogs to age 13 (P ≤ 0.02). Total bone mineral density was significantly lower for Expected compared to Exceptional and Long lifespan dogs (P < 0.04).

CONCLUSIONS

This study shows that life-long maintenance of lean body mass and attenuated accumulation of body fat were key factors in achieving a longer lifespan. The results suggest that a combination of a high quality plane of nutrition with appropriate husbandry and healthcare are important in obtaining a greater than expected proportion of Labrador retrievers living well beyond that of the expected breed lifespan: 89.7 % (95 % CI 74.8-96.7 %) dogs were alive at 12 years of age and 28.2 % (95 % CI 15.6-45.1 %) reaching an exceptional lifespan of ≥15.6 years.

The Companion Dog as a Model for the Longevity Dividend

The companion dog is the most phenotypically diverse species on the planet. This enormous variability between breeds extends not only to morphology and behavior but also to longevity and the disorders that affect dogs. There are remarkable overlaps and similarities between the human and canine species. Dogs closely share our human environment, including its many risk factors, and the veterinary infrastructure to manage health in dogs is second only to the medical infrastructure for humans. Distinct breed-based health profiles, along with their well-developed health record system and high overlap with the human environment, make the companion dog an exceptional model to improve understanding of the physiological, social, and economic impacts of the longevity dividend (LD). In this review, we describe what is already known about age-specific patterns of morbidity and mortality in companion dogs, and then explore whether this existing evidence supports the LD. We also discuss some potential limitations to using dogs as models of aging, including the fact that many dogs are euthanized before they have lived out their natural life span. Overall, we conclude that the companion dog offers high potential as a model system that will enable deeper research into the LD than is otherwise possible.