Imagine: A dog that growls when touched. A dog that hesitates before stairs, no longer jumps into the car, sleeps more, plays less, or becomes less tolerant in daily life... Many owners will think of a training problem, a temporary bad mood, or simply old age.

However, in veterinary behavioral medicine, chronic pain is now recognized as a frequent cause of behavioral changes.

It doesn't always manifest as an obvious limp or cries. In many cases, the first changes concern behavior: the dog avoids certain situations, interacts less, becomes more irritable, or simply appears different.

Understanding this link is important, as some dogs are treated for months for a behavioral problem when pain has been present for a long time...

What studies show

Several recent studies highlight that pain can be hidden behind behaviors mistakenly considered to be solely emotional or training-related.

The review by Mills and colleagues published in 2020 emphasizes that pain is still insufficiently investigated in dogs and cats presenting behavioral disorders. The authors recommend systematically integrating this hypothesis into clinical reasoning.

The work by Kwik, De Keuster, and their colleagues published in 2025 goes in the same direction. The authors reiterate that a significant proportion of dogs referred for behavioral problems also have a painful condition.

Depending on the studies and populations examined, between approximately 30% and 80% of dogs referred for behavioral disorders present at least one concomitant painful condition. The figures vary according to the criteria used and the centers studied, but they show that pain is not an exceptional cause.

Contrary to what might be thought, chronic pain does not only affect locomotor abilities.

The study by Malkani and colleagues in 2024 showed that painful dogs also exhibit alterations in their quality of life, emotional state, interactions, and general well-being.

Biological mechanisms

Chronic pain is not just a localized problem in a joint, muscle, or spine.

When it persists for several weeks or months, it influences various bodily systems. Stress mechanisms, alertness, sleep, emotions, and coping abilities can be altered.

A dog in pain can thus become more sensitive to certain situations, react more to handling, or tolerate less easily events it previously managed.

The relationship between pain and stress also works both ways. Pain increases the physical and emotional load, while stress, hypervigilance, or anxiety can amplify pain perception. This cycle can explain why some dogs gradually appear to become "more sensitive" even when no obvious lameness is yet visible.

What this means in daily life

The behavioral manifestations of chronic pain can be very varied.

Commonly found are:

• gradual social withdrawal;

• decreased play behaviors;

• decreased tolerance to contact;

• aggression during handling;

• unusual irritability;

• sleep disturbances;

• decreased initiative;

• reluctance to certain movements or activities.

A dog that no longer greets its owners, refuses certain cuddles, no longer enjoys brushing, or growls when moved is not necessarily becoming grumpy with age.

It may be trying to avoid pain, anticipate discomfort, or protect a sensitive area. This is what Barcelos and colleagues showed in aggressive dogs with subtle musculoskeletal pain.

Other signs may be more discreet:

• change of sleeping place;

• difficulty getting up;

• hesitation before stairs;

• refusal to get in the car;

• disturbed sleep;

• increased sensitivity to sudden approaches;

• decreased exploration or interest in the environment.

In many cases, behavioral changes appear before locomotor signs become obvious.

What is often misunderstood

"He growls because he's dominant"

A growl that appears during brushing, handling, getting up, or contact with a specific area should suggest pain before any hierarchical interpretation.

Several studies have shown that some aggressive dogs actually have underlying musculoskeletal pain.

"It's old age, you have to accept it"

Aging does increase the risk of osteoarthritis and chronic pain, but pain should never be considered normal.

An older dog that slows down, isolates itself, or changes its behavior deserves a veterinary evaluation.

"If he was really in pain, he'd be limping"

Chronic pain does not always cause visible lameness.

Some dogs compensate for their difficulties for a long time, especially when the pain is diffuse, progressive, or located in multiple places.

"It's a behavioral problem, not a medical one"

This opposition is artificial.

Pain can cause behavioral disorders, a behavioral problem can exacerbate certain pains, and both situations can also coexist.

Dogs most at risk

All dogs can be affected, but certain profiles require particular attention:

• older dogs;

• large and very large breeds;

• breeds predisposed to joint diseases;

• chondrodystrophic breeds prone to vertebral affections;

• dogs that have suffered trauma;

• operated dogs;

• dogs treated for behavioral disorders without satisfactory improvement.

In a dog presenting recent aggression, unusual anxiety, social withdrawal, or hypersensitivity, pain should be among the first hypotheses considered.

When to consult

A veterinary consultation is recommended when observing:

• a behavioral change without obvious cause;

• aggression during handling;

• a gradual refusal of previously enjoyed activities;

• unusual stiffness or slowness;

• a lack of improvement despite appropriate behavioral work.

The evaluation should not be limited to a few steps in the consultation room. Depending on the situation, it may require a complete clinical examination, a locomotor evaluation, and targeted complementary examinations.

When possible, filming the behaviors that concern owners (growls, difficulty getting up, hesitation, reactions to certain manipulations or changes in movement) can also provide valuable information to the veterinarian, as these behaviors are not always (often) visible during the consultation.

Recent publications remind us that a behavioral disorder should not be analyzed independently of the dog's physical condition.

Sources 

1. Kwik J, De Keuster T et al. Detection of Maladaptive Pain in Dogs Referred for Behavioral Complaints: Challenges and Opportunities. 2025.

2. Mills DS et al. Pain and Problem Behavior in Cats and Dogs. 2020.

3. Malkani R et al. How Does Chronic Pain Impact the Lives of Dogs: An Investigation of Factors Associated with Pain Using the Animal Welfare Assessment Grid. 2024.

4. Ghasempour M, Ünsal Gündüz HÖ. Dog Owners' Recognition of Pain-Related Behavioral Changes in Their Dogs. 2023.

5. Barcelos AM, Mills DS, Zulch H. Clinical Indicators of Occult Musculoskeletal Pain in Aggressive Dogs. 2015.

6. Camps T, Amat M, Manteca X. A Review of Medical Conditions and Behavioral Problems in Dogs and Cats. 2019.