Behavioral Aging in Dogs: What Changes Beyond Cognitive Decline

1. Why Behavioral Aging Needs Its Own View

1.1 More Than Cognitive Decline

Research on the aging dog has long been dominated by one question: when does an older dog develop cognitive dysfunction, and how can it be recognized? The focus is understandable, since cognitive dysfunction has a clear clinical picture and affects quality of life. The side effect is that almost every behavioral change in an older dog is read against the background of dementia, including changes that have nothing to do with it.

A large Australian owner survey addressed this directly by restricting its analysis to older dogs classified as cognitively normal (Salvin et al., 2011). Even in this group, age had effects on 18 behavioral items, with differences in incidence between age groups of 4.5% to 30.3%, and age was associated with deterioration over six months on 21 items. More than half of the items showed deterioration in over 10% of dogs. Activity and play levels, response to commands, and fears and phobias showed considerable deterioration. Problem behaviors and abnormal eating or movement patterns, by contrast, were rare, and the effect on memory and learning items was minimal.

The data are owner reports, but the point is clear: an older dog that plays less, responds less reliably to cues or becomes more fearful is not necessarily on the way to dementia.

1.2 When Is a Dog Old?

A perspective review proposed age groupings for pet dogs based on age-linked processes in the behavioral, cognitive and mortality literature (Harvey, 2021): puppy (0 to 6 months), juvenile (6 to 12 months), young adult (1 to 2 years), mature adult (2 to 6 years), senior (7 to 11 years, optionally split into early senior at 7 to 9 and late senior at 10 to 11) and geriatric (12 years and older), with an optional "very aged" category from 15 years. The review states that dogs aged seven years or older can safely be considered senior.

These boundaries are proposals, not empirically fitted cut-offs. The review is not exhaustive, most of the underlying data are cross-sectional, and breed and body size are not modeled. Because large dogs tend to live shorter lives, it seems logical to scale life stages by size. For behavior, that is less straightforward than expected. When the Australian survey grouped cognitively normal older dogs by expected longevity, height and pedigree status, arthritis prevalence differed by longevity and size, blindness differed by size, and longevity groups differed in excessive drinking and aggression displays (Salvin et al., 2012). Yet the authors concluded that the data did not suggest an increased rate of behavioral aging in large, short-lived dogs.

1.3 Normal Aging, Disease and the Gray Zone

Three kinds of change overlap in an older dog. The first is age-related change in the narrow sense: shifts in activity, attention, novelty seeking or sleep in otherwise healthy dogs. The second is change caused by conditions that become more common with age, especially pain and sensory loss. The third is cognitive dysfunction, a progressive neurodegenerative syndrome with characteristic clinical changes; assessment uses several clinical criteria and validated screening scales (what is known about cognitive dysfunction in aging dogs).

This article focuses on the first two and treats cognitive dysfunction only as a boundary. The distinction matters in practice. A dog whose behavior changes because of joint pain or hearing loss needs a different response than a dog with neurodegeneration, and treating every change as "just old age" risks missing conditions that can be addressed.

1.4 How to Read the Evidence

Most studies of behavioral aging are cross-sectional and cannot separate age from cohort effects. Several key studies used only Border Collies, and many large datasets rely on owner reports. These limits are noted where they apply and summarized at the end.

2. Personality Across the Lifespan

2.1 What Changes and What Stays

Whether personality traits remain stable with age was examined in Border Collies with a combined cross-sectional and longitudinal design (Turcsán et al., 2020). The cross-sectional part included 217 dogs aged 0.5 to 15 years; the longitudinal part retested 37 dogs after about 3.8 years.

Activity-independence decreased across the lifespan. Problem orientation increased until late adulthood and then plateaued. The largest change concerned novelty seeking, which was stable until about three years of age and then declined linearly. Sociability-obedience and frustration tolerance showed no significant change with age. Individual dogs differed in their trajectories, and a few aged outliers strongly affected the shape of the curves.

Limits include one breed, a battery that did not capture fearfulness or aggression well, a small longitudinal sample and possible test familiarity at retest. The study nonetheless shows that personality does not simply "fade" with age. Some traits decline, some rise, and some remain stable (how temperament and personality are studied in dogs).

2.2 A Controlled Trial in Older Pet Dogs

A one-year randomized, double-blind, controlled diet trial in older pet dogs offers an independent view (Chapagain et al., 2020). Of 119 enrolled dogs older than six years, 94 completed the study (45 on a test diet, 49 on a control diet). The dogs had a mean age of 9.1 years (range 6.1 to 14) and came from 30 breeds as well as mixed breeds. A modified test battery of eleven subtests was reduced to six factors: Problem Solving, Trainability, Sociability, Boldness, Activity-Independence and Dependency.

With increasing age, Problem Solving declined (η² = 0.15, p < 0.0001), as did Sociability (η² = 0.10, p = 0.002), Boldness (η² = 0.10, p = 0.002) and Dependency (η² = 0.07, p = 0.007). Trainability and Activity-Independence did not change with age. Neither the enriched diet nor the dogs' lifelong training history had an effect on any factor.

The intervention was short relative to a dog's lifespan, the diet combined several nutrients, undetected physical conditions may have influenced performance, training history was recalled by owners, and some factors had low internal consistency. Still, the age findings come from a controlled design with a broad breed mix.

2.3 A Rapid Test Battery

A preliminary study tested whether a short outdoor battery of eight subtests could capture age-related differences in family dogs (Kubinyi & Iotchev, 2020). Compared with 20 young dogs (1 to 5 years), fewer of 26 old dogs (10 to 15 years) approached when called (31% vs 60%) or followed (31% vs 70%), looked at their owner when a problem was blocked (15% vs 50%), chose correctly first in a memory task (15.5% vs 50%) or looked at a toy for a long time (29% vs 70%). Fewer old dogs avoided perseverative errors with a novel object (42% vs 75%), and owners rated old dogs as less active and excitable. The samples are small, the breeds had different lifespans, and healthy and pathologically aging dogs were not separated, so these are group differences, not a validated screening tool.

2.4 Aging Is Not One Uniform Decline

Together, these studies describe a pattern rather than a single slope. Novelty seeking, activity, sociability in tests and boldness tend to decline. Problem orientation can rise into late adulthood, and trainability, frustration tolerance and sociability-obedience remained stable where they were measured. An owner-rated scale of executive functions likewise found that different components follow different trajectories over the lifespan (Foraita et al., 2023). Some capacities are reduced, others remain available and can be used.

3. Attention and Learning in Normal Aging

3.1 Attention Follows an Inverted U

A cross-sectional study at the Clever Dog Lab in Vienna tested 145 Border Collies aged six months to 14 years in seven age groups (Wallis et al., 2014). It measured how quickly dogs oriented to a stimulus, how long they sustained attention to a human or a moving object, how quickly they switched to eye contact, how easily they were distracted, and how fast they found dropped food.

Sustained attention was higher toward a human (90.43% of the time) than toward objects (66.17%). Attention to objects declined with age, while attention to humans stayed close to its maximum. Task switching peaked in middle age (3 to 6 years), adolescent and geriatric dogs were more distractible, and sensorimotor performance was best in middle age. Prior clicker training was associated with faster eye contact. The authors caution that the same test may not reflect the same processes at different ages, that cohort effects are possible and that experimenters were not blind to age. Within these limits, attention improves into middle age and declines in geriatric dogs.

3.2 When the Slowing Becomes Visible

A follow-up study tested 185 pet dogs, 75 Border Collies and 110 dogs of other or mixed breeds, aged six to under eight, eight to under ten, and ten years and older (Chapagain et al., 2017). Geriatric dogs oriented more slowly than both younger groups (p < 0.001) and looked at the stimuli for a shorter time (p < 0.01), and the time needed to find dropped food increased with age (p < 0.001). Border Collies differed from other dogs only in the time to find food.

A higher lifelong training score from an owner questionnaire was associated with longer sustained attention and faster eye contact. This is an association: training history was reported retrospectively, and dogs that stayed attentive may also have been trained more. The study shows that attentional slowing becomes clearly visible from about ten years, not that training prevents it.

3.3 Learning New Discriminations

In a touchscreen study with 95 pet Border Collies aged five months to 13 years, older dogs learned new visual discriminations more slowly and showed perseverative responding, continuing to choose a previously rewarded option (Wallis et al., 2016). The study had no reversal task, a point that is often cited incorrectly.

Reversal learning was tested with 107 medium-sized to large family dogs, 41 young (2.5 to 6.5 years) and 66 old (8 to 14.5 years), in a single one-hour session with two spatial tasks (Piotti et al., 2018). Young dogs learned both the initial discrimination and its reversal significantly faster, and tasks based on location were more usable in old dogs than tasks based on object characteristics. Both studies point toward reduced flexibility in older dogs (what is known about behavioral flexibility in dogs).

Memory belongs more to the cognitive domain, but it shapes everyday behavior. A study of 90 clinically healthy dogs found poorer performance on an episodic-like memory task in older dogs (Sanches et al., 2022). This concerns healthy dogs and describes group differences, not individual diagnoses (what the research on episodic memory in dogs shows).

3.4 What Slower Learning Does and Does Not Mean

On average, older dogs orient more slowly, are more easily distracted, learn new discriminations more slowly and have more difficulty abandoning a learned response. This does not mean that they cannot learn. Trainability did not change with age in the controlled trial (Chapagain et al., 2020), and attention to a human remained high into old age (Wallis et al., 2014).

In practice: Older dogs often learn well when sessions are shorter, criteria are clear and the dog has more time to respond. This is an observation from training practice, not a finding from controlled studies, but it fits the slower orienting and reduced flexibility measured in the laboratory.

4. Activity, Play and Novelty

4.1 Less Activity During the Day

Accelerometer data over 14 days in 42 healthy dogs aged 2 to 9 years showed that younger dogs were significantly more active than older dogs during the daytime (p = 0.003), especially around the morning and evening activity peaks at about 7 a.m. and 7 p.m. (Woods et al., 2020). Since the oldest dogs were nine, the decline was measurable within adulthood. The dogs were not screened for chronic pain, and the method cannot distinguish quiet rest from sleep. Reduced activity in an older dog may therefore reflect age, but also undiagnosed discomfort.

4.2 Play and Shared Activity

In the survey of cognitively normal older dogs, activity and play levels were among the items with considerable deterioration (Salvin et al., 2011). A Hungarian owner survey of 1,207 dogs aged one year and older found the same for shared activities (Wallis et al., 2018): all four variables describing obedience tasks, play, commands and training activities were strongly influenced by age, with less activity in older dogs.

The direction of this effect is open: older dogs may play and train less because their motivation or capacity changes, or owners may offer less. The survey cannot distinguish these explanations (what the research on exercise and behavior shows).

4.3 Interest in Novelty

Reduced novelty seeking was the largest lifespan change in the Border Collie personality study (Turcsán et al., 2020), fewer old dogs looked at a toy for long in the rapid battery (Kubinyi & Iotchev, 2020), and Boldness declined with age in the controlled trial (Chapagain et al., 2020). Less interest in new things does not necessarily mean lower quality of life, but it changes how an older dog responds to new places and objects.

4.4 Activity Is Not Automatically Normal Aging

Less activity is the expected direction, but not every pattern fits it. In pet dogs with cognitive dysfunction, aimless or increased locomotion was linked to the severity of impairment rather than to age (Rosado et al., 2012). Restlessness, purposeless walking or pacing at night is therefore not the typical pattern of normal aging (see section 10).

5. Sleep

5.1 Sleep Changes Below the Surface

Older dogs often seem to sleep more, but changes in sleep go beyond quantity. Sleep spindles, short bursts of brain activity during non-REM sleep, were analyzed in 155 pet dogs aged 1 to 16 years with non-invasive polysomnography (Iotchev et al., 2019). With age, slow-spindle density declined at one recording site, while the frequency and, at another site, the density of fast spindles increased. Intact females had a higher fast-spindle density than intact males.

These are EEG markers, not behavioral observations, and their effect on learning or daytime behavior has not been established (how sleep relates to memory and emotion in dogs).

5.2 Rest Is Not the Same as Sleep

Activity monitors measure movement, not sleep (Woods et al., 2020): a dog that lies still longer may sleep more, rest, or avoid movement because it hurts. The distinction matters: sleep supports memory consolidation (how sleep supports learning in dogs), whereas resting because movement is painful points to a medical cause.

5.3 Where Sleep Changes Become a Sign

A polysomnographic study of 28 dogs aged 10.4 to 16.2 years found that dogs with higher scores on a dementia rating scale spent less time in non-REM and REM sleep during an afternoon recording (Mondino et al., 2023). Some EEG features differed with both age and cognitive performance. The sample is small, only afternoon naps were recorded, and age and impairment are hard to separate.

In dogs with diagnosed cognitive dysfunction, daytime sleep combined with restlessness at night was among the dominant signs (Fast et al., 2013). This reversal of the day–night pattern differs from the general tendency of older dogs to be less active during the day. A dog that sleeps more but still sleeps through the night shows a different picture from a dog that is awake and restless at night.

In practice: Older dogs often benefit from a sleeping place that is quiet, warm and reachable without stairs or slippery floors. This comes from practical experience rather than from studies, but it follows from the overlap between sleep, pain and mobility described here.

6. Sensory Decline

6.1 How Common Sensory Problems Are

In the Hungarian survey of 1,207 dogs, owners reported hearing or vision problems in an estimated 2% of dogs aged one to three years, 6% at over three to six, 4% at over six to eight, 14% at over eight to ten, 22% at over ten to twelve and 64% in dogs older than twelve (Wallis et al., 2018). The proportion of dogs described as healthy fell from 49% in the youngest group to 5% in the oldest. These are owner reports, not clinical diagnoses, but the steep rise in the oldest group shows how often a dog's perception changes in late life.

6.2 Hearing

Age-related hearing loss has been measured with brainstem auditory-evoked responses to toneburst stimuli in a study with cross-sectional and longitudinal components (ter Haar et al., 2008), so it is a measurable physiological change, not only an owner impression.

A more recent study combined clinical testing of hearing and vision in 91 dogs with an owner questionnaire on 238 dogs (Hopper et al., 2024). On clinical testing, hearing impairment was found in 4.8% of dogs younger than eight years and in 24.3% of dogs aged eight or older; in the questionnaire, the figures were 11.6% and 27.4%. The click stimuli used are not ideal for detecting high-frequency loss, so the clinical figures may underestimate it.

A dog that does not hear a cue cannot respond to it. Reduced response to commands, which owners commonly report in older dogs (Salvin et al., 2011), may therefore reflect hearing loss rather than reduced motivation or cognitive decline. The same applies to dogs that startle when approached from behind (how hearing works in dogs).

6.3 Vision

Vision impairment followed a similar pattern (Hopper et al., 2024): 2.2% to 2.3% of younger dogs on clinical testing and 4.2% to 9.9% in the questionnaire, compared with 14.3% to 23.8% and 23.8% to 25.6% of older dogs. A dog that hesitates on stairs at dusk or no longer responds to hand signals may have a vision problem rather than a behavioral one (how dogs see).

6.4 Smell

It is often assumed that odor-based performance remains intact into old age. A natural detection task with 411 untrained family dogs, who searched for food at three levels of difficulty, tested this (Salamon et al., 2024). Young adults aged two to three years were the most likely to reach the highest level, and all other age groups had lower odds. In late adult (6 to 8 years) and senior dogs (8 to 10 years), the odds were clearly reduced, by about 64% and 63%. Temperature, humidity, sex and neuter status had no effect. What was measured, however, was performance in an odor-based search task rather than the physiological sensitivity of the olfactory system alone; motivation, search strategy, endurance and other age-related factors may also have contributed.

The age categories were not breed-adjusted, the bait was strong, fatigue and satiety may have affected higher levels, and the dogs were untrained. For everyday life, the finding still matters: scent games remain useful for older dogs, but the difficulty may need adjusting (how olfaction shapes dog behavior).

6.5 Sensory Loss Confounds Cognitive Measures

Many signs used to identify cognitive decline, such as not responding to the owner, getting lost in familiar places or not recognizing people, can also result from poor hearing or vision. Dual sensory impairment was found in 7% to 14% of older dogs on clinical testing and in none of the younger dogs tested clinically (Hopper et al., 2024). Cognitive impairment was reported in 79% to 94% of dogs with dual impairment, compared with 25% to 27% of dogs without sensory impairment, and in dogs aged eight or older, dual impairment was associated with cognitive impairment (odds ratios 1.8 to 2.0). Questionnaires were less reliable than clinical measures, cut-offs came from young dogs, and most dogs had no objective cognitive testing.

In the Dog Aging Project cohort, owner-reported eye disorders (OR 2.16) and ear disorders (OR 1.96) were associated with higher odds of meeting the threshold for cognitive dysfunction on an owner-completed scale, and the authors state that they could not separate cognitive decline from sensory impairment (Yarborough et al., 2022). Hearing and vision loss can therefore influence behavioral assessment in older dogs and need to be considered when distinguishing cognitive dysfunction; these associations do not establish a causal direction.

7. Pain as a Hidden Driver

7.1 Osteoarthritis Becomes More Common With Age

In electronic health records of 455,557 dogs under primary veterinary care in the United Kingdom, the annual period prevalence of diagnosed appendicular osteoarthritis was 2.5% (Anderson et al., 2018). Risk factors included certain breeds, neutering, higher body weight and an age of more than eight years. Mean age at diagnosis was about 10.5 years, and the condition affected about 11.4% of an affected dog's lifespan. These are diagnosed cases; unrecognized osteoarthritis does not appear in records, so the true prevalence is likely higher.

7.2 "I Just Assumed It Was Old Age"

A qualitative study with interviews of 32 owners of 35 dogs and focus groups with 26 veterinary surgeons examined how osteoarthritis is identified (Belshaw et al., 2020). Owners noticed a wide range of typically subtle and intermittent changes in behavior and demeanor, and many waited months before seeking care. Less experienced owners in particular assumed that subtle changes in older dogs were part of normal aging, in one owner's words: "I just assumed it was old age".

The sample was purposive and relied on recall, so the study does not measure how often pain is missed. It shows a mechanism: the expectation that older dogs slow down can lead owners to read pain as aging (why dogs often hide pain).

7.3 How Pain Changes Behavior

A multi-author review drawing on referral caseloads reported a pain component in roughly 28% to 82% of specialist behavior cases, with a conservative estimate of about one third (Mills et al., 2020). These are selected caseloads, not prevalence data, but they show that pain is regularly found when behavior cases are examined carefully.

Dogs with osteoarthritis also showed widespread heightened pain sensitivity beyond the affected joint, likely indicative of central sensitization (Knazovicky et al., 2016). An older dog with joint disease may therefore react to touch on body parts that seem unrelated to the painful joint, and reactions to handling, grooming or being lifted can have a physical basis (how chronic pain and aggression are linked).

7.4 Overlap With "Normal" Aging

Many signs of pain overlap with what is usually called normal aging: less activity and play, reluctance to jump or climb stairs, slower rising, longer resting and less tolerance of handling. The studies in sections 2 to 4 rarely screened for pain; the accelerometer study states this explicitly (Woods et al., 2020), and the controlled trial notes possible undetected physical conditions (Chapagain et al., 2020). Some of what is described as behavioral aging may therefore be pain-related, but the current data do not allow this proportion to be estimated.

8. Fear, Anxiety and Noise Sensitivity With Age

8.1 Some Fears Become More Common

A Finnish owner survey of 13,715 dogs from 264 breeds found noise sensitivity to be the most common anxiety-related trait, reported in 32% of dogs (Salonen et al., 2020). Its prevalence increased with age, especially fear of thunder, and fear of surfaces and heights also increased with age. Hyperactivity and impulsivity and tail chasing decreased with age, and general fearfulness was most common between four and eight years.

These owner-reported associations do not show why noise sensitivity rises with age; accumulated experiences, hearing changes or pain are all possible. The pattern fits other findings: fears and phobias deteriorated considerably in cognitively normal older dogs (Salvin et al., 2011), and Boldness declined with age in the controlled trial (Chapagain et al., 2020).

8.2 Noise Sensitivity and Pain

One small study suggests that late-onset noise sensitivity may be connected with pain. It compared 20 clinical cases with noise sensitivity, ten with and ten without musculoskeletal pain (Lopes Fagundes et al., 2018). In the dogs with pain, noise sensitivity began at a mean age of 6 years and 6 months, compared with 2 years and 8 months in the others, and only the dogs with pain showed generalization of fear to places associated with the noise and new avoidance of other dogs.

With 20 dogs, this is a small case series, and the control dogs were not examined for undiagnosed pain. It cannot show that pain causes noise sensitivity. It does support a practical conclusion: noise fear that begins in an older dog, especially if it spreads to new situations, is a reason to look for pain (what is known about noise sensitivity in dogs).

8.3 Surfaces, Heights and Mobility

The age-related increase in fear of surfaces and heights (Salonen et al., 2020) is plausible in light of the other changes: a dog with joint pain may slip more easily on smooth floors, a dog with reduced vision may misjudge steps, and a dog that has slipped may start avoiding the surface. These are hypotheses, but they lead to a useful question: does the dog avoid a surface because it is afraid, because it hurts, or because it cannot see well?

9. Lifestyle Associations

9.1 The Dog Aging Project

The largest current source of data on aging in companion dogs is the Dog Aging Project, an open science study of a longitudinal cohort of tens of thousands of dogs (Creevy et al., 2022). The analyses cited here are cross-sectional and based on owner questionnaires, so they describe associations.

9.2 Physical Activity

An analysis of 11,574 dogs aged 6 to 18 years, 287 of which scored above the clinical threshold on an owner-completed cognitive dysfunction scale, examined physical activity (Bray et al., 2023). More active dogs had lower current scores (estimate −0.10, 95% CI −0.11 to −0.08), less worsening over six months (−0.07, 95% CI −0.09 to −0.05) and lower odds of meeting the clinical threshold (OR 0.53, 95% CI 0.45 to 0.63). The authors state that the design cannot determine causality. Activity may protect cognition, but dogs with beginning decline may also become less active, or both may depend on pain or general health.

The baseline analysis of 15,019 dogs found a similar pattern (Yarborough et al., 2022). Overall, 1.4% met the threshold for cognitive dysfunction. The odds rose with each year of age (adjusted OR 1.52, 95% CI 1.44 to 1.61), and inactive dogs had higher odds than very active dogs (OR 6.47, 95% CI 2.93 to 17.23). These, too, are cross-sectional associations from owner reports.

9.3 Social Environment

An analysis of 21,410 dogs found that financial and household adversity were associated with poorer health and lower mobility, while social support, such as living with other dogs, was associated with better health (McCoy et al., 2023). The association with social support was about five times stronger than that with financial factors, and associations varied with the dog's age. These are correlates of healthy aging, not demonstrated causes.

9.4 Training: An Association and a Null Result

A higher lifelong training score was associated with better attention in older dogs (Chapagain et al., 2017). In the one-year controlled trial, however, lifelong training showed no effect on any of the six behavioral and cognitive factors, and neither did the enriched diet (Chapagain et al., 2020). The two studies measured different outcomes in different samples, so they do not strictly contradict each other. Together they show that the evidence for a protective effect of training on behavioral aging is mixed, and that the positive finding is an association.

9.5 Where Intervention Data Exist

Positive intervention data come from two specific settings. In a two-year longitudinal study in laboratory beagles, behavioral enrichment and an antioxidant-fortified diet slowed age-related decline in learning ability, and the combination was more effective than either alone (Milgram et al., 2005). These were laboratory dogs with structured cognitive testing as part of the program, so the results do not transfer directly to companion dogs, and the pet-dog trial found no comparable diet effect (Chapagain et al., 2020).

The second is a lifelong diet restriction trial in 48 Labrador Retrievers kept in pairs (Kealy et al., 2002). Dogs fed 75% of their paired controls' intake lived longer (median 13.0 vs 11.2 years), and late-life diseases, especially osteoarthritis, began later. This is experimental evidence, but in one breed, and its link to behavior is indirect: later osteoarthritis means later pain-related behavior change (what overweight does to dogs).

The lifestyle data are consistent with the idea that activity, social contact and a lean body condition support healthy aging, but they do not show that a specific amount of exercise, a training program or a supplement slows behavioral aging in a companion dog.

10. The Boundary to Cognitive Dysfunction

10.1 Prevalence Rises With Age

Cognitive dysfunction becomes markedly more common with age. In 180 neutered dogs aged 11 to 16 years, 28% of dogs aged 11 to 12 were impaired in at least one behavioral category and 10% in two or more; at 15 to 16 years, the figures were 68% and 35% (Neilson et al., 2001). Mechanisms, diagnosis and treatment are covered elsewhere (how cognitive dysfunction is recognized and managed). This section only asks where normal aging ends.

10.2 Signs That Point Beyond Normal Aging

In pet dogs, the severity of cognitive impairment, not age, influenced locomotion and exploration, and more severe impairment went with higher locomotor activity and more aimless, corner-directed behavior (Rosado et al., 2012). In normal aging, activity tends to decline; aimless restlessness is not part of that pattern.

In 94 dogs with cognitive dysfunction followed over eight years, the dominant signs were daytime sleep with restlessness at night, decreased interaction, disorientation at home and anxiety, and survival was not reduced (Fast et al., 2013). In 51 dogs older than eight years, 33% of cognitively normal dogs progressed to mild cognitive impairment and 22% of mildly impaired dogs progressed to cognitive dysfunction (Schütt et al., 2015). Markers included aimless wandering, staring, avoiding being petted, difficulty finding dropped food and anxiety.

10.3 The Gray Zone

The boundary is not sharp. Difficulty finding dropped food also increased with age in normally aging dogs (Chapagain et al., 2017). Decreased interaction or anxiety can result from pain or sensory loss: a dog that avoids being petted may have widespread pain sensitivity (Knazovicky et al., 2016), and a dog that seems disoriented may not see well (Hopper et al., 2024). Mild cognitive impairment is a common intermediate stage, not a rare exception (Schütt et al., 2015). Sensory loss and pain are common, they produce signs that overlap with cognitive decline, and unlike neurodegeneration they can often be treated or compensated for. That is why they should be considered first.

11. What Follows for Practice

11.1 Not a Diagnosis, but a Reason to Look

This article describes research findings and cannot replace a veterinary examination. Any new or noticeably changing behavior in an older dog, especially a sudden change, a new fear, increased irritability, changes in sleep or reactions to touch, is a reason for a veterinary assessment. Waiting because "it is probably just age" is common and can delay recognition of treatable conditions (Belshaw et al., 2020).

11.2 What to Watch

Useful observations include how quickly the change appeared, whether it is constant or intermittent, whether it depends on time of day, surface, lighting or exercise, and whether it affects one behavior or many. A gradual decline in activity and novelty seeking over years fits the aging studies. A sudden change, a change that worsens after exercise, or one limited to certain movements or situations points more toward a specific cause.

In practice: A simple diary or short videos of the behavior are often more useful in a veterinary consultation than a description from memory. This recommendation comes from practical experience, not from studies, but it addresses the subtle and intermittent signs that owners describe (Belshaw et al., 2020).

11.3 Rough Orientation

The following is not a diagnostic scheme but a summary of the research. Normal aging tends to show as a gradual reduction in activity, play, novelty seeking and boldness, with slower orienting and slower learning of new tasks, while trainability and attention to people are largely preserved (Turcsán et al., 2020; Chapagain et al., 2020; Wallis et al., 2014). Pain is more likely when changes depend on movement, posture or touch, such as reluctance to jump, reactions to handling or noise fear that begins late and spreads (Lopes Fagundes et al., 2018; Knazovicky et al., 2016). Sensory loss is more likely when the dog misses cues of one modality but not another, startles when approached, or struggles in poor light or new places (Hopper et al., 2024). Cognitive dysfunction is more likely with day–night reversal, disorientation in familiar places, aimless wandering or staring, once pain and sensory loss have been considered (Fast et al., 2013; Schütt et al., 2015; Rosado et al., 2012). These categories often occur together, and only a veterinary examination can sort them in an individual dog.

11.4 Adapting Training and Environment

Older dogs orient more slowly and are more easily distracted, so they may need more time and a calmer setting (Wallis et al., 2014; Chapagain et al., 2017). They learn new discriminations more slowly and abandon learned responses less easily (Wallis et al., 2016; Piotti et al., 2018), so changing an established cue is harder than introducing a new one clearly. Location-based tasks were more usable in older dogs than tasks based on object features (Piotti et al., 2018), which suggests that spatial cues may be easier for some.

In practice: For dogs with hearing loss, hand signals and a light touch as a signal to look can replace verbal cues, ideally introduced before hearing is lost. For dogs with reduced vision, clear verbal cues, unchanged furniture and announcing an approach by voice help to avoid startle. These are practical recommendations, not study results. Handling for grooming and veterinary care can be supported by approaches that give the dog more predictability and control (how cooperative care works).

Given the age-related increase in fear of surfaces and heights (Salonen et al., 2020) and the rising risk of osteoarthritis (Anderson et al., 2018), non-slip floors, ramps instead of stairs or jumps, and easily reachable resting places are reasonable measures. The lifestyle data are associational, but they give no reason to restrict activity that a dog enjoys and tolerates (Bray et al., 2023), and search games remain useful with difficulty adjusted to declining olfactory performance (Salamon et al., 2024).

12. Summary at a Glance

Behavioral aging is broader than cognitive dysfunction. In cognitively normal older dogs, owners reported considerable deterioration in activity and play, response to commands, and fears and phobias, while problem behaviors and memory items changed little (Salvin et al., 2011). Senior status is often placed at about seven years, but life stages are proposals, and behavioral aging did not appear faster in large, short-lived dogs (Harvey, 2021; Salvin et al., 2012).

Novelty seeking declined from about three years in Border Collies (Turcsán et al., 2020). In a controlled trial with older pet dogs, problem solving, sociability, boldness and dependency declined with age, trainability did not, and neither diet nor lifelong training had an effect (Chapagain et al., 2020). Attention slowed clearly from about ten years (Wallis et al., 2014; Chapagain et al., 2017), and older dogs learned new discriminations and reversals more slowly (Wallis et al., 2016; Piotti et al., 2018).

Sensory problems become very common in late life (Wallis et al., 2018; Hopper et al., 2024), performance in an odor-based search task declined with age (Salamon et al., 2024), and sensory loss was associated with higher cognitive scale scores (Hopper et al., 2024; Yarborough et al., 2022). Osteoarthritis risk rises with age (Anderson et al., 2018), owners often attribute its signs to old age (Belshaw et al., 2020), and noise sensitivity becomes more common with age (Salonen et al., 2020). Lifestyle findings from large cohorts are associations, and the positive intervention data come from laboratory beagles and a calorie restriction trial (Milgram et al., 2005; Kealy et al., 2002).

13. Research Gaps and Critical Appraisal

13.1 Cross-Sectional Designs

Most studies compare dogs of different ages at one point in time (Wallis et al., 2014; Chapagain et al., 2017; Wallis et al., 2018), so age cannot be separated from cohort effects. The longitudinal component of the personality study included only 37 dogs (Turcsán et al., 2020), and the only randomized controlled trial in older pet dogs lasted one year (Chapagain et al., 2020). Long-term data on individual companion dogs are scarce.

13.2 Single-Breed Samples

Several key studies used only Border Collies (Wallis et al., 2014; Wallis et al., 2016; Turcsán et al., 2020), a working breed selected for attention and trainability whose aging may not represent other breeds. Where other breeds were included, breed comparisons were partly underpowered (Chapagain et al., 2017). How behavioral aging differs by breed and size remains largely open.

13.3 Owner Reports

The largest datasets rely on owner questionnaires (Salvin et al., 2011; Wallis et al., 2018; Salonen et al., 2020; Yarborough et al., 2022; Bray et al., 2023). Owners may read pain as aging (Belshaw et al., 2020), and the same bias could shape how they rate behavioral change.

13.4 Confounding by Pain and Sensory Loss

Few studies screened participants systematically for pain or sensory deficits (Woods et al., 2020; Chapagain et al., 2020). The cohort data cannot separate cognitive decline from sensory impairment (Yarborough et al., 2022), and the clinical sensory study used click stimuli that are suboptimal for high-frequency loss and cut-offs derived from young dogs (Hopper et al., 2024). How much of what is described as behavioral aging is undiagnosed pain or sensory loss is unknown.

13.5 Small Clinical Samples

Studies with clinical or physiological measures are often small: 20 cases on noise sensitivity and pain (Lopes Fagundes et al., 2018), 28 dogs on sleep and cognition (Mondino et al., 2023), 42 dogs in the actigraphy study (Woods et al., 2020) and 51 dogs in the progression study (Schütt et al., 2015). Their results need confirmation in larger samples.

13.6 Intervention Evidence

The positive intervention results come from laboratory beagles (Milgram et al., 2005) and from a diet restriction trial in one breed with osteoarthritis and lifespan as outcomes (Kealy et al., 2002). The one controlled trial in older pet dogs found no effect of an enriched diet or lifelong training on behavioral factors (Chapagain et al., 2020). Activity and social environment are associated with better outcomes in large cohorts (Bray et al., 2023; McCoy et al., 2023), but these associations have not been tested in intervention studies.

14. Conclusion

Behavioral aging in dogs is not one process but several. Reduced novelty seeking, less activity, slower orienting and slower learning of new tasks appear in healthy older dogs and follow a gradual course. Other changes come from conditions that become more common with age: sensory loss, which changes how a dog perceives and responds to its world, and pain, which affects movement, tolerance of touch and possibly the response to noise. Cognitive dysfunction lies at the far end of this spectrum, and its signs overlap with all of the others.

The most practical lesson is that "old age" is not an explanation in itself. Many older dogs remain trainable and attentive to people, and many changes that owners attribute to age have a cause that can be examined. Observing carefully, checking for pain and sensory loss, and adapting training and environment to what the dog can still perceive and do is more useful than expecting general decline.

Key Insights (Takeaways)

• Even in cognitively normal older dogs, owners reported considerable deterioration in activity and play, response to commands, and fears and phobias, while problem behaviors and memory items changed little (Salvin et al., 2011).

• Behavioral aging is not one uniform decline: novelty seeking, sociability and boldness decreased with age, while trainability, frustration tolerance and sociability-obedience remained stable (Turcsán et al., 2020; Chapagain et al., 2020).

• Attention followed an inverted U across the lifespan, with clear slowing from about ten years, and older dogs learned new discriminations and reversals more slowly (Wallis et al., 2014; Chapagain et al., 2017; Piotti et al., 2018).

• Sensory problems become common in late life and are associated with higher scores on cognitive scales; hearing and vision loss can therefore influence behavioral assessment and should be considered when distinguishing cognitive dysfunction (Wallis et al., 2018; Hopper et al., 2024).

• Osteoarthritis risk rises with age, and owners often attribute subtle signs of pain to old age (Anderson et al., 2018; Belshaw et al., 2020).

• Noise sensitivity becomes more common with age, and in a small case series, late-onset noise fear that generalized occurred in dogs with musculoskeletal pain (Salonen et al., 2020; Lopes Fagundes et al., 2018).

• Activity and social support are associated with healthier aging in large owner-reported cohorts, but a controlled trial found no effect of diet or lifelong training, and positive intervention data come from laboratory beagles and calorie restriction (Bray et al., 2023; Chapagain et al., 2020; Milgram et al., 2005; Kealy et al., 2002).

• New behavior changes in an older dog are a reason for a veterinary assessment, not something to accept as "just age".

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