Dog stress is often considered to be simple, temporary nervousness.

"It'll pass...", "It's nothing!", "He'll calm down", "Oh, he's always like that!" 

A dog that barks when its owner is away, scratches non-stop, trembles and refuses to eat when under severe stress, or is constantly on alert is often described as "sensitive", "anxious", or "just like that by nature".

However, the reality is often much more complex.

When a state of stress is repeated or becomes prolonged without allowing the body time to recover, it ceases to be considered a normal adaptive response. It then becomes a chronic biological state that can have consequences on a dog's behavior, immunity, digestion, skin, and hormonal balance (this also applies to humans, but that's not the subject of this article).

In dogs, several scientific studies show that a prolonged state of fear or anxiety can be associated with a deterioration in general health and, in some cases, a reduced life expectancy.

Understanding and recognizing chronic stress is not about dramatizing every behavioral difficulty. It simply allows for better recognition of certain signals sometimes mistakenly attributed to a dog's character, and enables the implementation of more appropriate responses (rest, environmental adjustments, educational support, veterinary follow-up if necessary, and gradual reduction of identified stress sources...).

What science shows

First, it's important to distinguish between acute stress and chronic stress.

Acute stress corresponds to a normal bodily reaction to a new, intense, or potentially threatening event. It allows the dog to quickly mobilize its resources: increased vigilance, accelerated heart rate, behavioral adaptation, or energy mobilization.

Once the situation is over, the body normally returns to its state of equilibrium.

Chronic stress occurs when stressful situations are repeated or persist without allowing for sufficient recovery. It is not necessarily dramatic. It can simply result from:

• an unpredictable environment;

• repeated separation anxiety;

• a long-standing fear;

• social restriction;

• a conflicting cohabitation;

• prolonged hospitalization;

• a lack of control over interactions.

Beerda and colleagues' work has shown that dogs subjected to social and spatial restrictions exhibited behavioral, hormonal, and immunological changes consistent with a state of chronic stress.

Another study conducted by Dreschel on over 700 dogs highlighted associations between certain anxiety disorders, certain skin diseases, and a decreased life expectancy in some particularly fearful individuals.

Even if these studies do not establish an absolute cause-and-effect relationship, they show that chronic stress should not be considered merely a behavioral problem.

Biological mechanisms

The hypothalamic-pituitary-adrenal axis (HPA axis)

The hormonal response to stress primarily relies on the hypothalamic-pituitary-adrenal axis, also known as the HPA axis.

When a stressor appears, the hypothalamus releases a hormone called CRH. This then stimulates the pituitary gland, which produces ACTH. This hormone, in turn, acts on the adrenal glands to increase cortisol production.

This mechanism allows the body to rapidly mobilize energy and adapt to the situation.

In the short term, this response is useful. When it is repeated for weeks or months, it can become problematic.

Cortisol is often referred to as the "stress hormone," but the reality is more complex. A single cortisol measurement is not enough to summarize a dog's emotional state or well-being.

The autonomic nervous system

In parallel with the HPA axis, the sympathetic nervous system also activates. This part of the nervous system acts as an alarm system: it prepares the body to react quickly by increasing alertness, heart rate, and energy availability. This response is useful in the face of a specific danger, but repeated activation can contribute to the establishment of a chronic stress state.

This results in particular in:

• an increased heart rate;

• an increased respiratory rate;

• heightened vigilance;

• increased reactivity.

When this activation is prolonged, it can contribute to maintaining a permanent state of hypervigilance.

The immune system

The link between chronic stress and immunity is now well-documented.

Stress does not systematically cause a "drop in immune defenses," but it can alter certain immune responses, disrupt certain inflammatory balances, or influence certain cell populations.

Studies conducted on dogs living in shelters or exposed to prolonged stress have shown measurable changes in certain immune responses.

In other words, a sustained state of stress does not remain solely "in the head." It can also have real physiological consequences.

What this can cause in daily life

A chronically stressed dog doesn't "do it on purpose."

Its body operates in a state of prolonged mobilization. Basically, it's constantly on "general alert."

This can manifest as:

• permanent hypervigilance;

• difficulties in recovering;

• sleep disturbances;

• repetitive behaviors;

• unusual irritability;

• a loss of interest in play;

• significant agitation.

Some signs are more discreet.

The owner may also observe:

• recurrent digestive problems;

• dermatitis;

• licking lesions;

• repeated ear infections;

• slower healing;

• changes in appetite.

Please note, these symptoms do not automatically mean that a dog is suffering from chronic stress, but they can be part of the clinical picture when no other cause explains the situation.

The most misleading thing is that a stressed dog is not always a dog that panics.

Some, on the contrary, become very calm, play less, interact less, or seem "well-behaved" when they have gradually adapted to a difficult situation.

Some misconceptions

- A calm dog is not necessarily a relaxed dog.

- Some dogs react to stress by withdrawing or reducing their interactions.

- Chronic stress is not just a behavioral problem.

- Prolonged emotions, fear, or anxiety can have real physical consequences.

- Finally, attributing certain fears to a dog's simple character can be simplistic. Individual sensitivity exists, but when a fear becomes lasting, diffuse, or debilitating, it often goes beyond mere personality.

Which dogs are most at risk?

All dogs can be affected.

However, some profiles seem more vulnerable:

• fearful dogs;

• noise phobias;

• separation anxiety;

• repetitive behaviors;

• past traumas;

• insufficient socialization;

• unstable environment.

Certain situations also increase the risk:

• unpredictable environment;

• conflicting cohabitation;

• prolonged hospitalization;

• extended kennel stay;

• punitive training methods;

• lack of control over interactions;

• under-stimulation or prolonged confinement.

When to consult?

A veterinary check-up should be considered in the presence of:

• repeated digestive issues;

• recurrent dermatitis or ear infections;

• chronic licking or scratching;

• significant changes in appetite;

• weight loss or gain;

• sleep disturbances;

• new aggression;

• social withdrawal;

• repetitive behaviors.

Behavioral support becomes particularly relevant when fear or anxiety significantly disrupt a dog's quality of life.

The longer a situation lasts, the more difficult it can become to correct...

Sources

1. Beerda B et al. Chronic stress in dogs subjected to social and spatial restriction. 1999.

2. Dreschel NA. The effects of fear and anxiety on health and lifespan in pet dogs. 2010.

3. Hekman JP et al. Psychogenic Stress in Hospitalized Dogs. 2014.

4. Salgırlı Demirbaş Y et al. 2023.

5. Mârza SM et al. 2024.

6. Kulka M et al. 2026.

7. Cobb ML et al. 2025.