When Behaviour Changes, Look Beneath the Surface
By Dr Ryan Morgan, Onward Veterinary Services ·
A dog growls when the harness goes on. A senior dog starts pacing at night. A dog who used to be social becomes reactive on walks.
Each of these can look like a training problem, and sometimes training is part of the answer. But behaviour is information, and sometimes the body is part of the message.
When a dog's behaviour changes, I often think of it as detective work. We observe the clues, consider what may have changed and ask better questions before deciding what the dog needs.
Behaviour and health are connected
Dogs cannot tell us that their back hurts when they turn a certain way, that they feel nauseated in the morning or that their joints ache after a long walk. Instead, discomfort may show up in movement, posture, sleep, appetite, tolerance or behaviour.
A dog in discomfort might:
- Hesitate before jumping into the car
- Shift their weight away from one limb
- Hold a leg out while sitting or standing
- Bob their head when walking
- Carry their tail differently
- Lick one area of their body excessively
- Become reluctant to use stairs or walk on slippery floors
- Struggle to settle, or start pacing overnight
- Avoid being touched, groomed or fitted with equipment
- Become irritable with people or other animals
- Lose interest in activities they used to enjoy
None of these signs proves that a dog is in pain, and a behaviour change can have many possible explanations. What each one does tell us is that something has changed, and that is worth looking into.
The dog who growls at the harness
We could read the growl as resistance or a handling problem. We could also ask:
Does lifting the front leg hurt? Is the harness rubbing somewhere? Has the dog developed neck, shoulder or back discomfort? Did something frightening happen while the harness was being put on? Is the dog worried about what the harness predicts?
More than one of these may be true.
The growl is a clue, and an important piece of communication. Punishing it may suppress the warning without addressing the reason behind it.
The threshold bucket
I often use the idea of a "threshold bucket" to explain why a dog may suddenly struggle with something they used to handle well.
Picture every demand on the dog adding something to a bucket:
- Pain or physical discomfort
- Poor sleep
- Hunger or nausea
- Noise
- Unfamiliar people
- Changes in routine
- Frustration
- Previous frightening experiences
- An exciting or stressful environment
One of these alone may not be enough to overwhelm the dog. When several pile up, the bucket can overflow.
What we see at that moment (barking, growling, freezing, lunging, hiding or refusing) is often the last visible event in a much longer story.
This is why a dog may react strongly on one walk and seem comfortable on the next. Their capacity can change from day to day depending on how full the bucket already is.
So beyond stopping the overflow, we want to find out what is filling the bucket and which parts we can reduce.
Pain and anxiety can exist together
It is tempting to sort behaviour into a medical issue or a training issue. In real life the line is rarely that tidy. A dog can have pain and anxiety at the same time.
Pain can make a dog more vigilant, less tolerant of handling and less able to recover from stress. Anxiety can increase muscle tension, interrupt sleep and make physical discomfort harder to cope with.
Treating discomfort will not automatically erase every learned fear or behavioural pattern, and training cannot be expected to overcome an untreated physical limitation.
Improving comfort may give the dog more capacity to learn. Behaviour support can then help the dog build confidence, predictability and safer ways through difficult situations. This is where veterinary care and qualified behaviour professionals work well together.
What to watch for at home
You know your dog's normal better than anyone. Small changes you notice at home can be valuable information in a veterinary or behaviour assessment.
Watch for changes in:
- Movement: Is your dog slower to rise, hesitant on stairs, taking shorter steps or shifting weight away from a limb?
- Posture: Has their head position, back shape, sitting posture or tail carriage changed?
- Daily routines: Are they sleeping differently, pacing overnight, avoiding certain surfaces or choosing different resting places?
- Handling: Have grooming, nail trims, harnessing or being picked up become more difficult?
- Social behaviour: Are they less tolerant of other dogs, children or physical contact?
- Activity: Have they stopped jumping, playing, climbing or joining in something they used to enjoy?
Short videos help. Try recording your dog walking toward and away from the camera, moving past it from the side, getting up from rest, using stairs or doing the activity that concerns you. Don't repeatedly provoke a painful or frightening response just to capture it.
When to talk to your veterinarian
A veterinary assessment is particularly important when:
- The behaviour appeared suddenly
- The dog's tolerance of touch or handling has changed
- Behaviour changes come with changes in movement, posture, sleep or appetite
- A previously comfortable activity becomes difficult
- The behaviour is escalating
- The dog is older
- There has been an injury, illness or change in medication
- Your instincts tell you something is not right
Urgent assessment may be needed if the change is accompanied by severe pain, collapse, weakness, difficulty breathing, repeated vomiting, inability to urinate, significant neurologic changes or another acute medical concern.
Keep more than one possibility open
We should not assume that every behavioural concern is caused by pain. Nor should we assume that a behavioural label rules out a medical contributor.
Sometimes the next step is a physical examination. Sometimes it includes diagnostic testing, a mobility assessment, environmental changes, a pain-management trial or a consultation with a behaviour professional. Often the most useful plan brings several of these together.
Start with curiosity
When behaviour changes, try replacing "Why is my dog doing this?" with a few more specific questions:
- What is different?
- When does it happen?
- What happens immediately before and afterward?
- Has anything changed in my dog's movement, sleep, appetite or routine?
- What might make this situation physically or emotionally difficult?
- What helps my dog feel safer or more comfortable?
Behaviour is information. It does not always give an immediate answer, but it gives us a place to begin. I treat a new behaviour change as possible pain until proven otherwise.
You are an essential part of that detective work. What you see at home is information your veterinarian needs, alongside the physical exam, to understand what a change in behaviour is telling us.
When we respond with curiosity rather than judgment, we can see the whole dog and build a plan that supports both comfort and learning.
If you share your home with a cat too, the signs of pain look different in cats.
When pain is part of the picture, our Wellness & Rehab service builds one plan around your dog, at home.
Worried about a change in your dog's behaviour? Book an in-home assessment. We look for pain and stress from every source, and work to reduce both.