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Understanding Cortisol and Stress in Dogs

Date: November 18, 2023

How to cite: Barata, R. (2023). Understanding Cortisol and Stress in Dogs, A Review. Human-Animal Science.

Cortisol, often called the "stress hormone," is vital in managing stress in humans and animals, influencing biological and psychological functions. Produced in the adrenal glands, it is integral to various bodily processes, including metabolism, immune response, and memory formation. Its presence, although constant, varies throughout the day, peaking in the morning and gradually declining by evening. These fluctuations are essential for maintaining health and homeostasis, making cortisol a critical focus in human and veterinary medicine and animal behavior studies.


Physiological Factors:

  • Stress: Both physical and psychological stress are primary triggers for increased cortisol production.
  • Sleep Patterns: Disruptions in sleep or irregular sleep patterns can affect cortisol levels.
  • Diet and Nutrition: Certain dietary patterns, such as high sugar or lack of certain nutrients, can influence cortisol.
  • Exercise: Physical activity impacts cortisol, with intense exercise typically increasing its levels.
  • Illness or Injury: The body's response to illness or injury often involves a rise in cortisol.
  • Hormonal Fluctuations: Changes in other hormones, like estrogen and testosterone, can affect cortisol levels.
  • Pregnancy: Cortisol levels naturally change during pregnancy.
  • Age: Cortisol levels can vary, often increasing as individuals age.
  • Breed and Genetics: Breed-specific traits and genetics can influence how cortisol is regulated in pets.

Psychological Factors:

  • Emotional Stress: Anxiety, depression, and other emotional states can lead to elevated cortisol levels.
  • Mental Health Disorders: Conditions like PTSD, anxiety disorders, and depression are often linked with altered cortisol levels.
  • Coping Strategies: How individuals cope with stress can impact their cortisol levels.
  • Personality Traits: Certain personality traits, such as a tendency towards anxiety or hostility, can influence cortisol production.

Environmental Factors:

  • Exposure to Light: Exposure to artificial light, mainly blue light in the evening, can disrupt cortisol rhythms.
  • Temperature and Climate: Extreme temperatures and climate conditions can impact cortisol levels.
  • Altitude: Higher altitudes have been shown to affect cortisol.
  • Seasonal Changes: Seasonal variations, like those in daylight and temperature, can influence cortisol patterns.

Social and Lifestyle Factors:

  • Social Interactions: Both positive and negative social interactions can influence cortisol levels.
  • Human Interaction: The quality and nature of human-animal interactions, including training and handling, can affect cortisol levels in pets.
  • Life Events: Major life events, whether positive or negative, can change cortisol levels.

Medical and Pharmacological Factors:

  • Medications: Certain medications, like corticosteroids, can directly influence cortisol levels.
  • Medical Conditions: Conditions like Cushing's syndrome or Addison's disease directly affect cortisol production.
  • Surgical Procedures: Surgical stress can lead to a temporary increase in cortisol levels.

In animals, it prepares the body for fight-or-flight responses and modulates long-term processes like metabolism and immune responses. However, cortisol's impact extends beyond acute stress scenarios, influencing how animals adapt to their environments and cope with stressors. This variability is influenced by genetics, environment, and past experiences.

For example, dog breeds may exhibit varying cortisol responses due to genetic predispositions. Similarly, an individual dog's experiences, like past trauma, can shape its cortisol response, manifesting in behaviors indicative of anxiety or stress. In cats, stress-related behavioral changes often manifest subtly, necessitating keen observation from owners for effective management.

The enhancement of learning is a positive aspect of cortisol, similar to its increased levels during courtship, mating, and efforts to obtain food. While cortisol's production in response to perceived threats, pain, or challenging environmental interactions is adaptive and beneficial, prolonged exposure to these stressors is inherently harmful. It can lead to adverse effects of cortisol. Given its role in advantageous and disadvantageous circumstances, viewing cortisol as invariably detrimental is incorrect.

An individual's welfare is determined by its ability to cope with its environment, with states ranging from excellent to poor. Welfare is compromised by difficulty or failure in coping. Coping strategies involve behavioral, physiological, and immunological responses coordinated by the brain. Emotions like pain, fear, and pleasure are often integral to these strategies and are crucial to understanding welfare. Good health is essential for positive welfare and is closely linked with coping with stress. Stress invariably indicates poor welfare, but temporary poor welfare may not always be due to stress (Broom & Johnson, 1993).

Certain environmental conditions, like inadequate housing, may not trigger a change in cortisol levels. Therefore, the absence of increased cortisol does not necessarily mean an animal is free of problems. Often, chronic issues prompt coping mechanisms that do not involve cortisol, leading to other adverse outcomes. Thus, various welfare indicators are necessary to detect problems in humans and non-humans. Brain damage can indicate poor welfare, especially in the hippocampus and related areas. Such damage may result from factors like high-fat diets, alcohol consumption, food restriction, or sleep deprivation, all without affecting cortisol levels. Abnormal behaviors, including stereotypies or heightened aggression, can also signal poor welfare in cases where cortisol levels remain unchanged. Cortisol fluctuations do not always indicate poor welfare; they may be natural responses to courtship or active food searching. Therefore, understanding the context of cortisol changes is crucial for accurately interpreting physiological data related to welfare.

Acute and Chronic Stress in Animals

As commonly understood, stress refers to environmental influences that overwhelm an individual's control systems, leading to negative outcomes and possibly diminished overall well-being (Broom & Johnson, 1993; Broom, 2014). This interpretation suggests that all stress is harmful, proposing that what is often termed 'good stress' should be classified as stimulation instead. Certain challenging situations can provide beneficial experiences during development, but these should not be categorized as stress. This concept aligns with Lazarus's (2006) view that stress occurs when demands are perceived to exceed personal capabilities. However, a more functional definition that applies universally to all animals, irrespective of perception, is favored.

Stress is an inevitable aspect of life, crucial for survival, and manifests in two primary forms: acute and chronic stress. These stress types are vital for wild animals and domesticated pets like dogs and cats. Acute stress, an immediate response to perceived threats, is exemplified by a deer's fight-or-flight reaction upon sensing a predator. This response involves a hormonal surge, including cortisol, leading to heightened alertness and readiness for action. In domestic animals, acute stress responses, although similar, are often triggered by different stimuli, such as thunderstorms for dogs or environmental changes for cats. Chronic stress, on the other hand, results from prolonged exposure to stressful situations. It can have detrimental effects, such as weakening the immune system in wild animals or causing behavioral changes in pets.

Distress and Eustress in Animal Stress Management

It is important to understand and manage stress in pets as it directly affects their overall well-being. This involves creating stable and safe environments, regular exercise, mental stimulation, and consistent routines. Behavioral therapy or veterinary care might be necessary for pets showing signs of chronic stress. Recognizing signs of chronic stress and understanding cortisol's role in these signs can aid pet owners in providing supportive environments.

Distress in Animals

Distress is a negative form of stress, often resulting from unpleasant or harmful stimuli. In both wild and domestic animals, distress can be acute or chronic. Acute distress might be a response to an immediate threat, such as a predator attack in the wild or a traumatic event like a car accident for a domestic pet. Such instances of distress, though intense, are usually short-lived. Chronic distress occurs with persistent stressors and a lack of adequate adaptation or recovery. This might include ongoing environmental challenges like habitat loss or food scarcity for wild animals. Domestic animals may experience chronic distress due to continuous mistreatment, neglect, or an unsuitable living environment. Chronic distress can lead to long-term health and behavioral issues.

Eustress in Animals

Eustress is a positive form of stress, beneficial and even essential for healthy development and functioning. It is typically associated with experiences perceived as challenges rather than threats and can be linked to both acute and chronic stress scenarios. In animals, acute eustress can be observed during playful activities or when encountering new, stimulating, non-threatening environments—for example, a dog learning a new trick or a cat exploring a safe outdoor space. Chronic eustress, though less common, occurs in environments that consistently provide positive challenges and stimulations, such as working dogs in search and rescue missions, where the stress is rewarding and fulfilling.

Distress vs. Eustress concerning Acute and Chronic Stress

While both distress and eustress can manifest as acute or chronic stress and may trigger similar bodily responses like the release of stress hormones, their impacts differ significantly. Distress generally has negative effects and can lead to health and behavioral problems. In contrast, eustress is associated with positive outcomes, including improved well-being and performance.

Integrating Distress and Eustress with Cortisol's Role

Understanding the interplay between distress, eustress, and cortisol is crucial in animal care and behavior management. While the alarmist perspective in dog training emphasizes cortisol's association with stress, recognizing the hormone's role in distress and eustress provides a more balanced view. For instance, elevated cortisol levels might indicate distress in some situations but could also signify eustress during engaging and positive experiences. Thus, interpreting cortisol levels requires context and an understanding that not all stress is harmful. Positive stressors leading to eustress are essential for mental and physical stimulation, promoting adaptability and resilience.

In managing stress in companion animals, creating environments that minimize distress while encouraging eustress is vital. This approach fosters a well-rounded development and ensures the overall well-being of animals. For dog trainers and behaviorists, this means adopting a balanced approach that recognizes the need for stress management and enriching positive stress experiences.

Cortisol in Dog Training: A Balanced Perspective

Recent trends in dog trainers' social media have emphasized cortisol's role in canine behavior, often leading to an overly cautious approach to avoid potential stressors. While well-intentioned, this alarmist perspective oversimplifies the complex role of cortisol in canine physiology and behavior. 

After conducting a thorough analysis, I have found several counterarguments that require careful consideration:

  • Cortisol's Dual Role: Cortisol is vital for numerous physiological processes and involves negative and positive stress.
  • Oversimplification of Stress Responses: Stress responses are complex and influenced by various factors. Not all stress is detrimental; short-term stress can be adaptive and necessary for development.
  • Neglect of Positive Stress (Eustress): Focusing solely on reducing cortisol can neglect the importance of eustress, which is essential for mental and physical well-being.
  • Variability Among Individual Dogs: Dogs vary in how they perceive and react to stimuli, necessitating a tailored approach in training and care.
  • Need for a Balanced Approach: Recognizing the need for stress management and enriching experiences is crucial in dog training.
  • Misinterpretation of Cortisol's Role: Often labeled solely as a "stress hormone," cortisol's role is more nuanced. While it is involved in the stress response, it is also vital for many normal bodily functions. The presence of cortisol is not inherently negative or indicative of a problem.
  • Overemphasis on Cortisol Levels: Excessively focusing on cortisol levels can misinterpret normal physiological responses as problematic. Stress, in moderation, is a normal part of life and can be beneficial, promoting resilience and adaptation. Not all increases in cortisol are harmful or indicative of distress.
  • Neglect of Individual Variability: Dogs, like people, have varying thresholds and stimuli responses. A one-size-fits-all approach in dog training, aiming to minimize cortisol production at all costs, may not suit every dog's needs and can overlook the importance of positive stressors (eustress) in their development.
  • Potential for Overprotection: Overprotective measures to avoid cortisol elevation might limit a dog's experiences, hindering their ability to develop coping mechanisms and resilience. Challenges and mild stressors are part of a healthy life and learning process for dogs.
  • Need for a Balanced Approach: A more balanced view recognizes the importance of managing distress and providing opportunities for positive stress. Understanding and appropriately responding to a dog's needs rather than adhering to a generalized fear of cortisol is critical to effective training and well-being.


Cortisol's role in animal physiology and psychology is multifaceted, significantly impacting stress management and behavior. This role varies greatly among individual animals, making it critical for pet owners, veterinarians, and animal behaviorists to understand these variations for optimal care. In dog training, a nuanced and balanced understanding of cortisol is essential, emphasizing the need to balance stress management with enriching experiences. This approach enriches the lives of pets and, in turn, enhances the human-animal bond, contributing positively to their health and well-being.




Broom, D. M. (2014). Sentience and Animal Welfare. Wallingford: CABI.

Broom, D. M., & Fraser, A. F. (2015). Domestic Animal Behaviour and Welfare (5th ed.). Wallingford: CABI.

Broom, D. M., & Johnson, K. G. (1993, reprinted with corrections 2000). Stress and Animal Welfare. Dordrecht: Springer.

Lazarus, R. S. (2006). Stress and Emotion: A New Synthesis. New York: Springer.