No, not that kind of arousal! 😉
Do you have a dog that just can’t settle in the evening after you come back from a walk or a game of chuck-it? Is your solution for this issue to go for another brisk walk and game of fetch?
If your dog has already pottied for the evening and there is no other physiological need that hasn’t been met, chances are they are in a state of over-arousal. A brisk play session or walk will only elevate their arousal level. I’m guessing that’s probably not your objective late in the evening!
Everyone needs some level of arousal to function, or we’d never get anything done! Optimal level means your dog is alert with ears pointing forward and they easily respond to cues. They are not panting heavily for prolonged periods of time, nor are their commissures (lips) pulled back tightly. Their pupils are not dilated.
Over-arousal (also called over-stimulation or hyper-arousal) in dogs triggers a cascade of physiological stress responses that are rooted in the same systems that handle fear, excitement, and survival threats. While it can look like “just excitement,” chronic or intense over-arousal taxes the body in measurable ways.
Here’s a breakdown of what happens physiologically:
Activation of the Sympathetic Nervous System (Fight–Flight Response)
When a dog becomes over-aroused (or over stimulated)
- The amygdala in the brain triggers the hypothalamus to activate the sympathetic nervous system (SNS).
- This releases catecholamines—primarily adrenaline (epinephrine) and noradrenaline (norepinephrine)—from the adrenal medulla.
Immediate physiological effects:
- Increased heart rate and cardiac output
- Rapid breathing (panting)
- Pupil dilation (to improve vision and focus)
- Vasoconstriction in the skin and gut; vasodilation in muscles (to shunt blood toward action)
- Heightened sensory alertness and muscle tension
Endocrine Response
If arousal continues beyond a brief burst (IE: Zoomie or FRAP being an example of a brief burst):
- The hypothalamic–pituitary–adrenal (HPA) axis releases cortisol from the adrenal cortex.
- Cortisol sustains energy by increasing glucose availability (via gluconeogenesis) and altering immune function.
Sustained or repeated over-arousal (stimulation)→ chronically elevated cortisol → physiological wear-and-tear can result in:
- Suppressed immune system
- Impaired digestion (vomiting, diarrhea, or refusal to eat)
- Muscle breakdown
- Slower tissue repair
- Increased susceptibility to inflammation or infection
Autonomic Imbalance
The parasympathetic nervous system (PNS)—responsible for “rest and digest”—is suppressed. Chronic imbalance between SNS and PNS can lead to:
- Elevated resting heart rate
- Sleep disruption
- Poor recovery after exertion
- Difficulty calming down even in safe environments
Neurochemical Effects
- Dopamine surges during high excitement reinforce the behavior that led to the arousal (“that was fun—do it again! Think Zoomie or FRAP)
- If not paired with appropriate down-regulation or rest, this cycle can create addictive-like patterns of reactivity.
- Serotonin balance can be disrupted, reducing impulse control and emotional stability.
Physical Manifestations of Over-Arousal
These can resemble both excitement and stress:
- Panting, shaking, or trembling
- Zoomies that look frantic or repetitive spinning
- Barking, lunging, mouthing, or nipping
- Inability to focus or respond to cues
- Dilated pupils, tight facial muscles, or “hard” eyes
- Sudden urination or defecation
- Collapse or exhaustion after intense bursts (post-adrenal dump fatigue)
Chronic Effects if Unmanaged
If over-stimulation becomes a regular pattern, the persistent high cortisol and sympathetic dominance can contribute to::
- Behavioral problems (reactivity, anxiety, compulsive behavior)
- Immune suppression and skin or GI disorders
- Muscle tension, orthopedic strain, or cardiac stress
Recovery and Regulation
So what do you do if this is happening with your dog? After a vigorous workout, or game of chuck-it, the physiological recovery requires re-engaging the parasympathetic system:
- Adequate rest (dogs need 14-16 hours/day). Do what you can to ensure your dog has a place where they can rest undisturbed
- Use calm, structured activities that avoids flooding or chaotic play (play “find it!”, nose work or even Rally obedience). I play a modified version of Leslie McDevitt’s 1-2-3 game after my dog has a run in the field. Keep predictable routines and allow for sniffy walks in calm environments.
- Support of neurochemical balance through calm behaviour, not suppression.
Remember: Encourage calm behaviour, but don’t punish over-arousal. Over-arousal isn’t “bad behavior.” It’s physiology. Help your dog’s body recover ⏤ not just “burn it off.”
Reference:
“Beyond Cortisol! Physiological Indicators of Welfare for Dogs: Deficits, Misunderstandings and Opportunities” (Cobb, Jimenez, Dreschel; 2025, preprint) https://arxiv.org/abs/2502.11384?utm