Does My Dog Really Have a Behavior Problem? What the 99% Study Got Wrong

Not every unwanted or commonly reported dog behavior is a behavior problem. A reanalysis of more than 43,000 dogs shows why frequency, severity, development, welfare and safety have to be considered separately.

 

You may have seen the claim that more than 99 percent of dogs in the United States have at least one moderate to serious behavior problem. That statistic came from a real scientific study using data from more than 43,000 dogs. But a subsequent reanalysis of the same dogs found that the way the original study grouped and classified behaviors substantially exaggerated the apparent prevalence of behavior problems.

 

There is a larger lesson for dog owners here.

 

A dog doing something you do not like is not automatically a dog with a behavior disorder. A behavior being common does not make it abnormal, and a behavior appearing on a questionnaire does not tell us whether it needs professional treatment.

 

Before deciding that your dog has a "behavior problem," I want to know what the dog actually does, how often it happens, how intense it is, when it happens, whether anyone is at risk, whether the dog's welfare is impaired, and, especially with puppies, where the dog is developmentally.

 

An Example

 

Years ago, I was hired because the student’s boyfriend didn’t like her dog looking at him. That wasn’t a dog behavior problem, he had a problem. And they had a relationship problem that no dog trainer could fix.

 

Do 99 percent of American dogs really have behavior problems?

 

No scientific evidence currently establishes that 99 percent of American dogs have meaningful behavior problems.

 

In 2024, veterinary behaviorist Bonnie Beaver analyzed mini C-BARQ questionnaire data from 43,517 dogs enrolled in the Dog Aging Project. The paper reported that 99.12 percent had at least one behavior problem classified as moderate to serious. It also reported 55.6 percent for "aggression," 49.9 percent for fear and anxiety, and 85.9 percent for separation and attachment behaviors. (Beaver, 2024). James Serpell and Lauren Powell subsequently reanalyzed the same dataset using the established factor structure of the mini C-BARQ. Their conclusion was very different. They argued that the original analysis grouped behaviors that should not have been combined and used thresholds that tended to inflate apparent prevalence and severity. (Serpell & Powell, 2026).

 

The reanalysis does not tell us the exact percentage of American dogs that truly have behavior problems either. Serpell and Powell point out that a representative population sample would be necessary to establish that number.

 

That is important. The correction to a bad estimate is not to invent another overly precise estimate.

 

What percentages did the reanalysis find?

 

The answer depends greatly on what is measured and where the threshold is placed. Serpell and Powell calculated prevalence using both a score of 2 or greater and a more stringent score of 3 or greater. The difference is substantial.

 

Behavior measured by mini C-BARQ	Score 2 or greater	Score 3 or greater
Stranger-directed "aggression"	10.0%	1.5%
Owner-directed "aggression"	1.2%	0.3%
Dog-directed "aggression"	30.4%	11.0%
Familiar-dog rivalry	10.5%	3.2%
Nonsocial fear	15.6%	2.4%
Dog-directed fear	28.2%	9.0%
Stranger fear	14.1%	4.2%
Separation-related behavior	9.3%	2.3%
Attachment/attention-seeking	88.9%	55.7%
Escaping or attempting to escape	29.8%	14.1%
Urinating against objects indoors	3.7%	0.9%
Urinating while alone	6.2%	1.8%
Defecating while alone	4.4%	1.1%
Tail or hind-end chasing	11.0%	2.5%
Persistent barking when alarmed or excited	46.9%	22.7%

 

These are questionnaire scores. They should not be read as percentages of dogs with diagnosed behavioral disorders. That distinction is the point.

 

How did separation behavior go from 85.9 percent to 9.3 percent?

 

The original analysis combined two different things: separation-related behavior and attachment/attention-seeking behavior. When those factors were separated in the reanalysis, 9.3 percent of dogs met the score-2 threshold for separation-related behavior, while 88.9 percent met that threshold for attachment and attention-seeking. At the stricter score-3 threshold, separation-related behavior fell to 2.3 percent.

 

That makes biological sense. Dogs are social animals that have been selected for thousands of years to form relationships with humans. A dog following you around the house, wanting proximity, seeking attention or choosing to lie near you is not equivalent to a dog experiencing serious distress when left alone. If we combine ordinary social attachment with abnormal separation behavior, we can manufacture an alarming statistic without necessarily identifying an alarming population. This is why a behavior label is not an explanation.

 

Does 55.6 percent "aggression" mean more than half of dogs are violent?

 

No. This is another place where terminology can mislead the reader. The mini C-BARQ category called "aggression" includes behaviors such as growling, barking and baring teeth at intermediate levels. The highest end of the scale includes snapping, biting or attempting to bite. Serpell and Powell specifically point out that a dog that growls or barks when a delivery person approaches the house can therefore contribute to an "aggression" score.

 

For practical assessment, I do not consider a threat display and a physical attack to be the same event. A growl is behavior. Baring the teeth is behavior. Barking at a stranger approaching the property is behavior. Those signals may be important and may indicate that further assessment is warranted, but they are not interchangeable with a bite or an attack.

 

The more useful questions are: What exactly did the dog do? To whom? Under what circumstances? At what distance? How often? What happened next? Was contact attempted or made? Was anyone injured? Once those questions are answered, the word used to label the behavior becomes much less important than the behavior itself.

A 2026 study by Normando and colleagues demonstrates just how much the question itself can manufacture an apparent prevalence rate. Among 569 dog owners, only 32.7% spontaneously reported at least one behavioral problem when asked an open-ended question. When owners were instead presented with a list of behaviors to consider, 99.0% identified at least one. Even the order of the questions affected their answers. The study does not tell us that 32.7% is the “true” prevalence of behavior problems. It tells us something more important: a prevalence figure can partly measure the questionnaire rather than the dog. Before calling a behavior a problem, we still have to ask what the dog actually does, under what circumstances, how often, how intensely, with what consequences, and whether it meaningfully compromises the dog, the household, or public safety. (ScienceDirect)

 

We do not currently have a credible basis for saying that 99% of dogs have behavior problems. The percentage depends heavily on what researchers call a problem, how behaviors are grouped and scored, what cutoff is chosen, how questions are framed, and which population is sampled.

 

When is a dog behavior a problem?

 

I think owners get better answers if we stop trying to put everything into one box called "behavior problems." For practical purposes, I would separate at least four possibilities.

 

1. Normal canine behavior that humans find inconvenient. Dogs bark, dig, chew, chase, sniff, seek social contact and respond to things happening around their homes. Normal does not mean desirable in every household. It means that the presence of the behavior alone does not establish pathology.

2. Developmental behavior. Puppies and adolescents are not finished dogs. House-training capacity, oral behavior, attention, emotional responses, social behavior and impulse control change as dogs mature. Some problems diminish with maturation while others emerge or become clearer during adolescence. Rather than a behavior problem, these combine a lack of maturity with a lack of proper training repetitions.

3. A training or management problem. A normal behavior may still interfere substantially with life in the household. Jumping on visitors, pulling on leash, counter surfing, barking or poor household manners may require training and management even when nothing is wrong with the dog. Dogs need training, they don’t come trained “out of the box.” Owners need training, too. I had no clue what to do with my first dog, and I had to enroll in classes to figure out solutions. My dog didn’t have a behavior problem, nor did I have a behavior problem. We had a lack of training.

4. A welfare or safety problem. Severe distress, inability to function normally, repeated escape attempts, injurious behavior, serious fear, self-injury, biting and attacks belong in a different category. These are not equivalent to a puppy chewing your shoe.

 

The purpose of assessment is to determine which problem you have before deciding what to do about it.

 

Which puppy problems might improve as the puppy develops?

 

Some puppy behaviors genuinely change as the nervous system, body and social behavior mature.

 

Researchers who filmed 32 puppies home alone three times during the first months after adoption found that only three showed a cluster of stress-associated behaviors such as substantial vocalization, lip licking and oral behavior. Those behaviors decreased substantially across subsequent observations and did not persist at the same level. (Cannas et al., 2010).

 

Young puppies also commonly vocalize when socially isolated. Separation protest has been described as an adaptive juvenile response, and nighttime disturbance and house soiling in newly adopted puppies often decline as puppies mature and adjust to their new environment.

 

That does not mean you should ignore puppy problems.

 

House-training still requires management. Chewing still requires supervision and appropriate outlets. Puppies still need to learn skills. Preventable experiences can affect later behavior. What maturation means is that I would be cautious about interpreting every difficulty in a ten-week-old puppy as evidence of a permanent adult behavioral disorder.

 

Which puppy problems should I not assume the dog will outgrow?

 

Do not use "he's just a puppy" as an excuse to ignore a worsening trajectory. Behavior does not uniformly improve with age. In a large study of prospective guide dogs, measurable behavioral changes occurred between six and twelve months. Some characteristics decreased while others increased, and the changes differed among breeds. German Shepherd Dogs in that population, for example, showed increasing stranger-directed "aggression" scores between six and twelve months. (Serpell & Duffy, 2016). (Please recall: “aggression” isn’t the same as posturing and vocalizations, but are often lumped in together as one. Truly, scholars should know better, but often even they need more training.)

 

That should not be interpreted as a prediction about every German Shepherd. It demonstrates the larger developmental point: the puppy you see today is not necessarily a miniature version of the adult dog.Genetics, breed tendencies, maturation, learning, environment and experience continue to interact.

 

This is why I am more concerned about direction than about one isolated observation. Is the behavior diminishing, remaining stable, becoming more intense, occurring in more situations, or becoming harder for the dog to recover from?

 

Which behavior problems can I reasonably work on myself?

 

Many owners can begin with ordinary household and puppy-training problems themselves.  That can include house-training, age-appropriate chewing, puppy mouthing that is not causing a serious safety concern, jumping, basic leash skills, mild attention-seeking, common household manners, and mild developmental difficulties that are already improving.

 

The goal is not necessarily to suppress every normal dog behavior. Often the job is to provide an appropriate outlet, prevent rehearsal of unwanted behavior, teach an alternative, and set expectations that fit the dog's developmental stage.  Track progress rather than demanding perfection.

 

If accidents are becoming less frequent, the puppy can remain alone comfortably for gradually longer periods, recovery is getting faster, or an unwanted behavior is becoming easier to interrupt and redirect, those trends provide useful information. You are on track. Some puppies are very easy right from the start. 

 

Some.

 

When should I get professional help?

 

Professional assessment makes sense when the stakes, frequency, intensity, severity or uncertainty exceed what can reasonably be handled by trial and error by a novice dog owner. Or when you are in over your head with a particular dog.

 

I would be especially concerned about biting or attacks; repeated attempts to bite; behavior creating a meaningful risk to children, adults or other animals; severe or escalating fear; panic or sustained distress when left alone; self-injury; dangerous escape behavior; sudden major behavioral change; inability to find any situation in which the dog can work or interact successfully; behavior that continues to deteriorate despite reasonable management and training; or signs suggesting pain or another medical contribution.

 

Separation-related behavior deserves the same kind of careful definition. Barking a little when you leave, following you from room to room, and prolonged distress with pacing, destruction, uncontrolled elimination, and extreme vocalization can’t all be lumped in together as the same problem. Research on separation-related behavior also shows why context matters: the behavior must be associated with separation rather than simply occurring at another time.

 

If a behavior appears suddenly, particularly in an adult dog, veterinary evaluation may need to be part of the assessment.

 

So does my dog have a behavior problem?

 

Start by describing the behavior instead of naming the problem. Write down what the dog does, what happens immediately before it, who is present, where it happens, how often it occurs, its intensity, what ends it, how quickly the dog recovers, and whether the pattern is changing. Then ask a second question:

 

Is this primarily normal behavior, development, a training and management issue, a welfare concern, or a safety concern?

 

That distinction matters far more than whether your dog helps push a population survey above or below some statistical threshold. And if you don’t know, it is time to make a call.

 

The lesson from the 99 percent controversy is not that canine behavior problems are rare. Some are common, some are serious, and some can profoundly affect dogs and the people who live with them.

 

The lesson is that measurement is not diagnosis, a behavior is not automatically a disorder, and prevalence depends heavily on how we define what counts as a problem.

 

If your dog is having a behavior problem and you are not sure which category it belongs in, an individualized assessment can help identify what the dog is doing, the circumstances in which it occurs, and what kind of intervention is justified.

 

You can learn more about working with me at SamTheDogTrainer.com.

 

Glossary

 

Aggression: Violence.

Behavior problem: A broad and partly subjective term for behavior considered undesirable, harmful, disruptive or concerning. The term does not itself identify cause, severity or appropriate treatment.

 

C-BARQ: The Canine Behavioral Assessment and Research Questionnaire, a standardized owner questionnaire developed to measure behavioral and temperament characteristics in dogs.

 

Mini C-BARQ: A shortened form of C-BARQ used in the Dog Aging Project and other research.

 

Developmental behavior: Behavior influenced by the dog's current stage of physical, neurological and social maturation.

 

Separation-related behavior: Behavior occurring specifically in association with separation from human companionship, which may include vocalization, destruction, pacing, elimination or other behaviors.

 

Attachment/attention-seeking: Social behavior involving proximity to or interaction with familiar people. Its presence by itself does not establish separation distress.

 

Threat display: Signaling behavior such as growling, barking or baring teeth. A threat display can be important for risk assessment but should not automatically be equated with physical attack.

 

Prevalence: The proportion of a population displaying a specified characteristic during a defined period or under specified measurement criteria.

 

Threshold: The score selected by researchers as the dividing point between categories. Changing the threshold can substantially change the percentage of subjects placed into a category.

 

Bibliography

 

Beaver, B. V. (2024). The prevalence of behavior problems in dogs in the United States. Journal of Veterinary Behavior, 76, 34–39. doi:10.1016/j.jveb.2024.11.001.

 

Cannas, S., Frank, D., Minero, M., Godbout, M., & Palestrini, C. (2010). Puppy behavior when left home alone: Changes during the first few months after adoption. Journal of Veterinary Behavior, 5(2), 94–100. doi:10.1016/j.jveb.2009.08.009.

 

Dale, F. C., Burn, C. C., Murray, J., & Casey, R. (2024). Canine separation-related behaviour at six months of age: Dog, owner and early-life risk factors identified using the Generation Pup longitudinal study. Animal Welfare, 33, e60. doi:10.1017/awf.2024.56.

Normando, S., Canori, C., Borlini, M., Zanetti, R., Walsh, E. A., Meers, L. L., & Contalbrigo, L. (2026). How questions on dog behavioural problems may shape caretaker answers. Applied Animal Behaviour Science, 304, 107134. https://doi.org/10.1016/j.applanim.2026.107134 (ScienceDirect)

 

Serpell, J. A., & Duffy, D. L. (2016). Aspects of juvenile and adolescent environment predict aggression and fear in 12-month-old guide dogs. Frontiers in Veterinary Science, 3, 49. doi:10.3389/fvets.2016.00049.

 

Serpell, J. A., & Powell, L. R. (2026). Prevalence and severity of behavior problems in dogs in the United States: A re-assessment. Journal of Veterinary Behavior, 83, 8–13. doi:10.1016/j.jveb.2025.11.005.

 

Wilkins, V., Evans, J., Park, C., Dog Aging Project Consortium, Fitzpatrick, A. L., Creevy, K. E., & Ruple, A. (2024). Validation of the shortened version of the Canine Behavioral Assessment and Research Questionnaire (C-BARQ) using participants from the Dog Aging Project. PLoS ONE, 19(4), e0299973. doi:10.1371/journal.pone.0299973. 

My Dog Is “Reactive”: What Does That Actually Mean?

Calling a dog “reactive” describes someone’s impression of the dog’s behavior, but it does not identify what the dog is doing, why it is happening, or what training approach is appropriate. If someone tells me, “My dog is reactive,” I still do not know what the dog does.

 

Does the dog bark? Lunge? Whine? Pull toward other dogs? Retreat from them? Stare? Growl? Spin at the end of the leash? Try to make contact? Bite? Does it happen with every dog, only certain dogs, only on leash, only near the house, only behind a fence, or only when another dog gets too close?

 

“Reactive” may be convenient shorthand, but it is not an explanation of behavior. Before deciding how to train the dog, we need to get underneath the label and determine what is happening.

 

Is “reactive dog” a scientific term?

 

“Reactive dog” is not a standardized scientific diagnosis or a single scientifically defined category of dog.

 

The word reactivity certainly appears in scientific research, but that is different. Researchers must define what they mean by the term and specify which observable behaviors count as reactivity in a particular study.  That distinction is important.

 

A 2024 paper in the Journal of Applied Animal Welfare Science examined how people understand canine “reactivity” and noted that there is no consensus in either scientific literature or ordinary usage about exactly what the term encompasses. The researchers found a complex and sometimes contradictory mixture of ideas involving both characteristics of the dog and human perception. PubMed

 

A 2025 shelter study made the problem even more explicit. The authors wrote that canine reactivity is not precisely defined and recognized that judgments about reactivity involve both the dog's behavior and the human observer's perception of what constitutes appropriate behavior. The researchers therefore had to create a specific definition for their own study. MDPI

 

That is how science is supposed to work. If you are going to measure something, you first have to say exactly what counts. Everyday conversations about “reactive dogs” usually do not do that.

 

Can two people look at the same dog and disagree about whether the dog is reactive?

 

Absolutely. Part of the label exists in the eyes of the beholder. One owner may consider barking twice at another dog normal excitement. Someone else may call the same dog reactive. One trainer may reserve the term for intense barking and lunging. Another may include whining, leash pulling, staring or difficulty disengaging.

 

Experience also changes how people interpret canine behavior. Research has shown that people's ability to identify emotional states in dogs varies with their experience with dogs, and other work has found substantial difficulty matching behavioral and emotional labels with their intended definitions. PMC

 

This does not mean behavior is merely subjective. The dog really did something. The problem is that the label and the behavior are not the same thing.  “Barked six times, pulled hard toward the other dog, and stopped barking when the other dog was about 40 feet away” gives me information. “He was really reactive today” gives me someone's summary of that information.

 

Those are not equivalent.

 

Does a reactive dog mean a stressed or frightened dog?

 

No. Stress or fear may be reasonable hypotheses in some cases, but the label “reactive” does not establish either one.  There is a popular explanation that reactive dogs react because they are struggling, frightened, uncomfortable or stressed. Sometimes that may be exactly what is happening. Sometimes it may not.

 

The same outward behavior can occur under very different circumstances. A dog pulling and vocalizing toward another dog might be attempting to increase distance. Another might be intensely trying to approach. Another might have a history of conflict with certain dogs. Another may be highly aroused by movement. Another may have learned a particular leash sequence through repetition. Physical discomfort, developmental history, genetics, previous encounters, restraint, owner behavior and competing motivations can also be relevant. The behavior is evidence. The proposed emotional or motivational explanation is an inference. That distinction is fundamental.

 

Isn’t my dog communicating something when he reacts?

 

Possibly, but saying “behavior is communication” can also become another shortcut if we stop there. Animals certainly use behavior to communicate. Growls, postures, vocalizations, orientation, approach and withdrawal can convey information to other animals and people. But observing behavior does not automatically tell us its cause, function or the dog's complete internal state.

 

A bark is something the dog did. Calling that bark a communication of fear, frustration, threat, excitement or stress requires additional evidence.

 

Classical ethology gives us a useful warning against overly simple explanations. Niko Tinbergen argued that understanding behavior requires asking different kinds of questions, including questions about immediate causation, development, function and evolutionary history. Those questions cannot simply be collapsed into one convenient explanation. ScienceDirect

 

So my preference is to say: Behavior gives us information. It does not interpret itself.

 

Does “reactive” mean aggressive?

 

No. “Reactive” and “aggressive” should not be treated as interchangeable words. A dog may bark, whine, leap around, pull or display conspicuous postures without committing violence. Another dog may give relatively little display and then bite.

 

That is one reason catch-all labels can become dangerous. Loudness and spectacle can attract human attention, while the behavior that matters most for safety may be something else entirely.

 

A recent 2026 study demonstrates the problem particularly well. Researchers first had to develop a working definition of a “dog reactive dog.” Their definition included barking, growling, snarling, lunging, snapping, nipping, biting, whining and certain postures. When they analyzed 1,360 complete behavioral profiles, those behaviors did not form one uniform phenomenon. The analysis produced different components and four behavioral subtypes with differing escalation risk. ScienceDirect

 

In other words, even after researchers deliberately created a category called “dog reactive dogs,” the dogs inside that category were behaviorally heterogeneous. That is exactly why the label should begin an investigation rather than end one.

 

If “reactive” does not explain the problem, what should I describe instead?

 

Describe what the dog does and the conditions in which it happens.

 

If I were assessing the problem, I would want to know things such as:

 

• What does the dog do?
• What is the dog responding to?
• How close   is the other dog, person, bicycle or other stimulus when the behavior begins?
• Does distance change the behavior?
• Does it happen on leash, behind fences, through windows or when the dog is loose?
• Does it happen with every dog or only certain dogs?
• Does the direction of approach matter?
• Does movement matter?
• Does the dog's behavior differ with different handlers?
• What happens immediately before the behavior?
• What happens immediately afterward?
• How easily does the dog disengage?
• How quickly does the dog return to ordinary activity?
• Has the pattern recently changed?
• Are there physical or medical concerns that warrant veterinary evaluation?

 

Now we have something we can investigate.

 

“Reactive” cannot answer any of those questions.

 

Why can two dogs that look reactive need completely different approaches?

 

Because similar visible behavior can be produced by different combinations of conditions. This is one of the ideas that experienced working-dog trainer Armin Winkler emphasizes from a different training tradition. Winkler rejects the idea that dogs deliberately cheat, insult the handler or knowingly choose to “do wrong.” But importantly, he does not replace that moral explanation with a single emotional explanation.

 

In his discussions, you will learn performance failures can involve incomplete teaching, competing motivation, arousal, fatigue, genetics, physical limitations, environmental conditions or consequences created by previous training. No dog has EVER knowingly done something wrong.

 

That is a much more useful way to think about a dog labeled reactive. The alternatives are not simply: “He is a jerk.” Or. “He is stressed.”

 

Both can prematurely stop the investigation.

 

The useful question is: What combination of variables best explains this particular dog's behavior in this situation?

 

Is reactivity a tame problem or a wicked problem?

 

You cannot tell from the word “reactive.” I have written elsewhere about the difference between tame and wicked problems in dog training. A tame problem has a reasonably clear target, established procedures and measurable outcomes. A wicked problem involves interacting variables, incomplete information, changing conditions and competing explanations. (Sam the Dog Trainer)

 

The distinction comes originally from the work of Horst Rittel and Melvin Webber on complex problem solving. Wicked problems resist single, final solutions because the definition of the problem and the attempted solution interact. DOI

 

Some dog problems called “reactivity” may turn out to be comparatively narrow. Others involve developmental history, physical state, genetics, learning history, environmental management, social relationships, owner handling and recurring circumstances that cannot be reduced to one technique.

 

My own rule is simple: A behavior label is not an explanation, and the training exercise should follow from the assessment rather than from the label.

 

Should I yell at or punish my dog for reacting?

 

Getting angry at the dog is not a substitute for determining what happened or teaching the dog what you want instead. Calling the dog stubborn, bad, dominant or a jerk adds a moral judgment without explaining the behavior. Yelling after an episode may also create additional conflict while doing very little to clarify what the dog was supposed to do differently. But the opposite oversimplification is also unhelpful. We should not reason that because all “reactivity” represents stress, every possible interruption or consequence is therefore inappropriate. We have not established that all dogs carrying this label are in the same state or behaving for the same reason.

 

Winkler makes a useful distinction between teaching and correction. In his framework, teaching establishes the behavior first; correction concerns interrupting a competing behavior after the relevant skill is known; retaliatory “payback” after the fact is something different again. No dog has EVER knowingly done wrong.

 

Whatever training philosophy someone uses, that distinction exposes an important error: you cannot fairly say the dog “refused” a behavior until you have established what the dog learned, under what conditions it was learned, and whether the behavior was accessible under the present conditions.

 

What should I do first if my dog is called reactive?

 

Start by managing safety and collecting better information. Creating additional distance can be an excellent immediate decision when a dog is escalating around another dog, person or moving object. Distance can reduce conflict and give the owner more options. It does not require us to pretend that we already know why the dog reacted. Likewise, bringing useful rewards may help you reinforce workable behavior when the dog can respond to you. But neither treats nor distance constitute a diagnosis.

 

The next job is to identify the smallest conditions under which the dog can encounter the relevant situation without the problem escalating, then compare those conditions with the situations where the behavior breaks down. Assessment comes before prescription.

 

When does professional assessment make sense?

 

Professional assessment becomes especially useful when the behavior is worsening, includes biting or attempted biting, creates a safety problem, varies dramatically between situations, prevents ordinary activities, or does not improve despite sensible management and training.

 

Veterinary evaluation also makes sense when there has been a significant change from the dog's previous baseline or there are possible physical or medical contributors.

 

An in-home assessment can be particularly useful because behavior described as reactivity frequently depends on context: the neighborhood, fences, doorways, other household dogs, the owner's handling, familiar walking routes and the distances available in the dog's actual environment. The purpose of assessment is not to attach a more impressive label. It is to discover which variables matter.

 

“Reactive” should start the assessment, not finish it

 

If you tell me your dog is reactive, I know that someone has seen behavior that seemed unusually intense or problematic. I do not yet know what the dog did, why the dog did it, what state the dog was in, whether the same thing happens elsewhere, or what intervention is appropriate. That is the distinction I want dog owners to remember.

 

“Reactive” is a catch-all description. It is not a root cause.

 

Start with the observable behavior. Compare contexts. Separate what you know from what you think might explain it. Then build the training plan from the evidence. If your dog has a similar problem and you are not sure what changes between the situations where the behavior succeeds and fails, an in-home assessment can help identify the relevant variables and build the training plan from there.

 

You can learn more about working with me at SamTheDogTrainer.com.

 

Glossary

 

Reactive / Reactivity: A broadly used descriptive label for conspicuous or intense responses to stimuli. In ordinary dog-training use, it has no single standardized definition.

 

Operational definition: A precise statement of what will count as a particular phenomenon for purposes of observation or research.

 

Observation: A description of what occurred without assigning a cause, such as “the dog barked and pulled toward another dog.”

 

Inference: A conclusion drawn from observations, such as the hypothesis that distance, restraint, fear or competing motivation contributed to the behavior.

 

Hypothesis: A proposed explanation that can be tested against additional observations or evidence.

 

Context: The surrounding conditions in which behavior occurs, including location, distance, people present, restraint, other animals and preceding events.

 

Tame problem: A problem with a relatively clear definition, established methods and measurable outcomes under appropriate conditions.

 

Wicked problem: A complex problem involving interacting variables, incomplete knowledge, changing circumstances and no single final solution.

 

Bibliography

 

Gilchrist, R., & Wynne, C. D. L. (2025). Reducing human-directed kennel reactivity in shelter-housed dogs. Pets, 2(2), 17. https://doi.org/10.3390/pets2020017. MDPI

 

Rittel, H. W. J., & Webber, M. M. (1973). Dilemmas in a general theory of planning. Policy Sciences, 4, 155-169. https://doi.org/10.1007/BF01405730. DOI

 

Stephens-Lewis, D., Johnson, A., Turley, N., Naydorf-Hannis, R., Scurlock-Evans, L., & Schenke, K. C. (2024). Understanding canine “reactivity”: Species-specific behaviour or human inconvenience? Journal of Applied Animal Welfare Science, 27(3), 546-560. https://doi.org/10.1080/10888705.2022.2147007. PubMed

 

Tinbergen, N. (1963). On aims and methods of ethology. Zeitschrift für Tierpsychologie, 20(4), 410-433. https://doi.org/10.1111/j.1439-0310.1963.tb01161.x. Wiley Online Library

 

Van Haevermaet, H., Soulsbury, C. D., & Mills, D. S. (2026). Reactive and risky: The behavioural structuring of “dog reactive dogs.” Applied Animal Behaviour Science, 299, 106961. https://doi.org/10.1016/j.applanim.2026.106961. ScienceDirect

 

Winkler, A: https://rivannak9services.com

My Dog’s Behavior Has Changed: Should I Call a Dog Trainer or a Veterinarian?

If your dog has become unusually tired, is losing weight, moving differently, behaving differently, or no longer doing things normally, do not assume it is a training problem. A meaningful change from the dog’s normal baseline may need veterinary evaluation before a training plan makes sense.

 

A dog that suddenly or progressively becomes less active, loses weight or muscle, stops doing things it previously did easily, or shows a substantial change in behavior should not automatically be treated as having a training problem. My first question is not, “How do we make the dog do it?” My first question is, “What changed, and is this dog presently in a condition to do what we are asking?”

 

As a dog trainer, I can observe changes, compare behavior across situations, document what an owner is seeing, and recognize when veterinary evaluation should come before or accompany training. I cannot diagnose why a dog has changed, interpret a blood panel as a medical diagnosis, or prescribe treatment for a medical condition. Those are veterinary questions.

 

My dog has become lethargic or is losing weight. Is that a behavior problem?

 

Not necessarily, and I would not start by treating it as one.

 

Consider a dog that had historically been active and muscular but becomes noticeably lethargic over several weeks and then begins losing weight. Perhaps the dog is still eating normally. Those observations tell us something important has changed, but they do not tell us why. That distinction matters.

 

Observed: the dog is less active than before, has lost weight, and is reportedly still eating.

 

Inferred: there may be a physical, medical, nutritional, behavioral, environmental, or other explanation for the change.

 

Unknown: the cause.

 

The mistake is jumping from the observation to an explanation. “She is getting old,” “he is depressed,” “she needs more exercise,” “he is being lazy,” and “she just needs motivation” may all sound plausible. None is established merely because the dog has become less active.

 

Veterinary guidance supports taking changes such as progressive lethargy, behavior changes, weight loss and mobility changes seriously as clinical information, particularly as dogs age. The American Animal Hospital Association specifically discusses these types of changes as part of the history and evaluation of an unhealthy senior animal. AAHA

 

Why does a change from my dog’s normal behavior matter?

 

A change from an individual dog’s baseline can be more informative than whether the behavior looks unusual in isolation.

 

Suppose one dog has always been quiet, sleeps much of the afternoon and dislikes long walks. That history is very different from a dog that eagerly walked several miles every day and now repeatedly stops after a few minutes. The second dog has given us comparative information. Something changed.

 

This is one reason I ask owners what the dog was doing before the problem began. I want to know whether the dog can still do the activity somewhere else, whether endurance has changed, whether the problem appeared gradually or suddenly, and whether other parts of the dog’s daily routine changed at about the same time.

 

A baseline does not diagnose the dog. It gives us something against which the present dog can be compared.

 

Can pain or illness look like a dog-training problem?

 

Yes. Physical conditions can alter behavior, which is why a trainer should not assume every behavioral change requires a behavioral solution. Veterinary pain guidelines emphasize that changes in behavior can be important indicators of pain. Reduced activity, reluctance to move, altered interaction, changes in posture and newly appearing behavior can all be relevant observations. AAHA Research in clinical animal behavior also describes relationships between painful     conditions and problems presented as behavioral complaints. Mills and colleagues have specifically cautioned veterinarians and non-veterinary behavior professionals against overlooking possible pain when evaluating problem behavior. PMC

 

That does not mean a trainer should look at a reluctant dog and announce, “Your dog is in pain.” The behavior does not establish that conclusion. It means pain or another medical condition may remain among the possibilities until appropriately evaluated.

 

There is a substantial difference between saying, “Your dog is refusing to jump because he has arthritis,” and saying, “Your dog used to jump into the vehicle readily and now repeatedly refuses. Before I design a training program to overcome that refusal, I want your veterinarian to know about the change.” The first statement diagnoses. The second reports an observation and respects an important professional boundary.

 

What can a dog trainer legitimately do when a dog has changed?

 

A trainer can help define the problem accurately without pretending to know its medical cause. If you tell me your dog “doesn’t want to exercise anymore,” I may want to know what that means in observable terms. Does the dog hesitate when leaving the house? Walk normally for ten minutes and then slow down? Refuse stairs? Still chase a ball but no longer jump into the car? Play normally in the morning but not later in the day? Those differences matter.

 

A trainer can also notice patterns that may not be obvious during a veterinary appointment because the veterinarian usually sees only a small sample of the dog’s life. The owner and trainer may have observations from the home, walks, play, training and normal daily activities.

 

Those observations can be useful to the veterinarian. They still are not a substitute for veterinary examination and diagnosis. My job is not to turn observations into veterinary conclusions. My job is to make the observations better.

 

What information should I record for my veterinarian?

 

Record what is actually happening rather than trying to solve the case yourself. Useful information can include the approximate date the change was first noticed; previous and current body weights if known; changes in normal activity or endurance; how much food the dog is actually receiving and whether appetite changed; changes in drinking, urination or bowel movements; changes in sleep; reluctance to climb, jump, sit, lie down or get up; changes in play or social interaction; current medications and supplements; and short videos showing activities that have changed.

 

Videos can be particularly useful because the veterinarian may not see the same movement or behavior during an office visit. AAHA's senior-care guidance specifically recognizes owner observations, pictures and videos as useful ways of documenting changes over time. AAHA

 

The purpose is not to assemble evidence for your own diagnosis. It is to provide better evidence to the professional responsible for making the medical assessment.

 

Can I interpret my dog’s bloodwork myself or ask people online what it means?

 

A laboratory report is one piece of a veterinary assessment, not a diagnosis by itself. It is tempting to photograph a blood panel, post it online and ask strangers what is wrong with the dog. Individual numbers may appear normal, high or low, but interpreting their significance requires the rest of the clinical picture.

 

AAHA's senior-care guidelines make this point explicitly: diagnostic interpretation and clinical diagnosis are considered together with the animal's clinical presentation, laboratory findings and, when appropriate, other diagnostic information. AAHA

 

That is why I would not interpret an owner's blood panel as a dog trainer. I can look at the history and say, “There has been a meaningful change from this dog's previous condition.” I can help the owner organize observations and questions. I can suggest that the owner discuss those changes and the test results with the veterinarian who examined the dog. I cannot legitimately turn laboratory numbers into a veterinary diagnosis.

 

What does “state before skill” mean in dog training?

 

It means I want to know whether the dog is in an appropriate physical and behavioral state to participate before deciding that failure to perform is a training failure.

 

Suppose a dog that normally sits readily begins avoiding the sit. I could increase reinforcement, practice more repetitions or try to make the dog comply. But I have skipped an important question: Why did a previously easy behavior become difficult?

 

The same principle applies when a dog suddenly walks more slowly, stops jumping, becomes irritable when handled, sleeps differently, has house-training accidents, withdraws from interaction or loses enthusiasm for activities it previously enjoyed.

 

These observations do not prove a medical cause. They tell us that simply increasing training pressure may be the wrong first response. Training should follow assessment. It should not be used to erase evidence that the dog has changed.

 

What if the change is aggression, fear or another obvious behavior problem?

 

A new behavior problem can still justify asking whether something else changed at the same time.

 

A dog that begins growling when touched, suddenly avoids stairs, becomes less tolerant of handling or develops a new reluctance to participate in normal activities presents a different assessment problem from a dog that has displayed the same pattern for years.

 

Again, that does not mean “aggression equals pain” or “fear equals illness.” Those would be unjustified conclusions. It means the dog's physical condition belongs in the assessment rather than being excluded merely because the owner's complaint sounds behavioral. Research on pain and behavior has repeatedly emphasized that pain may produce, contribute to or exacerbate behavioral changes. PMC

 

When should I involve a veterinarian, a trainer, or both?

 

When a dog has a significant unexplained change in physical condition, activity, weight, mobility or normal behavior, veterinary assessment may need to come before treating the problem as primarily a training issue. After that, the veterinarian and trainer may have different but complementary jobs.

 

The veterinarian determines whether there is a medical problem, what treatment is appropriate, and whether there are restrictions or considerations that affect activity. The trainer can then design training around the dog's actual abilities, environment and behavior rather than around an assumed explanation.

 

Sometimes the veterinarian finds an important medical problem. Sometimes the medical evaluation does not identify an explanation for the behavior. Either outcome is useful because it changes what we reasonably know about the case. For behavior that depends strongly on what happens at home, during walks or in ordinary family routines, an in-home training assessment can then be particularly useful because those are the conditions in which the relevant behavior actually occurs.

 

Why I Do Not Diagnose Medical Problems as a Dog Trainer

 

Veterinary medicine is a licensed profession throughout the United States, although the exact wording of veterinary practice laws and their exceptions varies from state to state. State veterinary boards regulate who may practice veterinary medicine, and diagnosis and medical treatment are core activities generally reserved to licensed veterinary professionals. The American Association of Veterinary State Boards represents regulatory bodies in all 50 states, and its model Veterinary Practice Act defines veterinary practice broadly to include diagnosing an animal's condition, determining health or soundness, and recommending or providing medical treatment. AAVSB For that reason, as a dog trainer I can report that a dog has lost weight, become less active, changed the way it moves, stopped performing behaviors it previously performed, or otherwise departed from its normal baseline. I can also recommend that the owner take those observations to a veterinarian. What I should not do is convert those observations into a medical diagnosis, interpret laboratory results as establishing a disease, prescribe medical treatment, or tell an owner that a particular medical condition is causing the behavior. That boundary is not simply about avoiding liability. It protects the dog by making sure medical questions are answered by the professional qualified and legally authorized to answer them.

 

The important question is not “How do I make my dog do it?”

 

The better first question is often, “Why has something my dog normally did become different?” A change in behavior is evidence. It is not automatically a diagnosis, and it is not automatically a training problem.

 

Observe the change carefully. Establish what is different from the dog's previous baseline. Let the veterinarian handle medical interpretation. Then build the training plan from what is actually known about the dog. That is state before skill.

 

If your dog is having a similar behavioral problem and you are not sure what is changing between the situations where the behavior succeeds and fails, an in-home assessment can help identify the relevant variables and determine an appropriate training starting point.

 

You can learn more about working with me at SamTheDogTrainer.com.

 

Glossary

 

Baseline: The dog's usual pattern of activity, behavior, physical ability or other measurable characteristics before the current change.

 

Clinical sign: An observable feature that may be relevant to an animal's health. A clinical sign does not by itself establish a diagnosis.

 

Observation: Something actually seen, measured or reliably reported, such as a dog walking less distance than previously.

 

Inference: A possible explanation drawn from observations. An inference should not be presented as an established fact without adequate evidence.

 

Veterinary diagnosis: The professional determination of an animal's medical condition based on appropriate clinical information and veterinary judgment.

 

Veterinary referral: Directing an owner to a veterinarian when information relevant to the dog's health falls outside the trainer's professional role or requires medical assessment.

 

Bibliography

 

1. Dhaliwal, R., Boynton, E., Carrera-Justiz, S., Cruise, N., Gardner, M., Huntingford, J., Lobprise, H., & Rozanski, E. (2023). 2023 AAHA Senior Care Guidelines for Dogs and Cats. Journal of the American Animal Hospital Association, 59(1), 1-21. https://doi.org/10.5326/JAAHA-MS-7343. PubMed
2. Gruen, M. E., Lascelles, B. D. X., Colleran, E., Gottlieb, A., Johnson, J., Lotsikas, P., Marcellin-Little, D., & Wright, B. (2022). 2022 AAHA Pain Management Guidelines for Dogs and Cats. Journal of the American Animal Hospital Association, 58(2), 55-76. https://doi.org/10.5326/JAAHA-MS-7292. PubMed
3. Mills, D. S., Demontigny-Bédard, I., Gruen, M., Klinck, M. P., McPeake, K. J., Barcelos, A. M., Hewison, L., Van Haevermaet, H., Denenberg, S., Hauser, H., Koch, C., Ballantyne, K., Wilson, C., Mathkari, C. V., Pounder, J., Garcia, E., Darder, P., Fatjó, J., & Levine, E. (2020). Pain and problem behavior in cats and dogs. Animals, 10(2), 318. https://doi.org/10.3390/ani10020318. MDPI