If you have ever watched your dog or cat and had the feeling that something was wrong without being able to point to anything specific you may have been picking up on the early signs of pain. Animals do not display discomfort the way humans do. They have evolved to conceal it.
Learning how to identify pain in dogs cats can help owners recognise subtle changes before discomfort becomes more severe.
Pain is the fourth vital sign in veterinary medicine, according to the Merck Veterinary Manual listed alongside heart rate, respiratory rate, and temperature. Yet it is consistently the hardest to assess because pets cannot describe it, and because their instinct is to hide it.
This guide covers the physical and behavioural signals that trained veterinarians look for, and how to identify them early enough that treatment is still straightforward.
Why dogs and cats hide pain
The behavioural drive to conceal pain is evolutionary. In a pack or colony setting, displaying weakness signals vulnerability to predators and to being displaced within the social hierarchy. Domesticated dogs and cats retain this instinct even though their circumstances have changed entirely.
The practical consequence for owners is significant: by the time a pet shows pain that is undeniable yelping, crying, obvious limping the condition has usually been present for some time. A 2026 PLOS One study examining 647 participants found that dog owners consistently underestimated the degree of pain their dogs were experiencing, even when presented with behavioural evidence.
Catching pain early requires knowing what subtleness looks like.
This is also where AI help detect pet health problems by helping owners assess combinations of physical and behavioural changes.
Physical signs of pain in dogs
Mobility and movement changes
Mobility changes are among the most reliable early indicators of pain in dogs. PetPace’s 2026 guide identifies intermittent limping that worsens after rest as a hallmark of arthritis, particularly significant because owners frequently observe this as ‘better once warmed up,’ which it is. Stiffness that improves with movement is still pain.
- Limping or favouring one leg, particularly after rest
- Reluctance to climb stairs, jump, or get in and out of the car
- Slower pace on walks, stopping earlier than usual, or refusing to go at all
- A change in how the dog carries itself head lower, back slightly hunched, altered posture
- Difficulty getting up or lying down extended hesitation before transitioning positions
Understanding these signs is an important part of knowing how to identify pain in dogs cats, particularly when changes are subtle.
Facial expression and posture
Cornell University’s College of Veterinary Medicine identifies specific facial expression changes as pain indicators: flattened ears, grimacing, glazed eyes, and a change in the area around the eyes. Dogs in pain often show subtle tightening of the muscles around the eyes, a ‘squinting’ look that is not from bright light.
Hunched posture, a tucked abdomen, or a dog that holds its neck extended downward are all postural signals that trained veterinarians note as potential pain indicators.
Breathing and vocalisation
Excessive panting at rest when the dog has not been exercising and is not in a hot environment is a frequently overlooked pain signal. Dogs pant when they are in pain as a physiological stress response. If your dog is panting while lying still in a comfortable environment, something is worth investigating.
Uncharacteristic vocalisation whining, growling, or yelping when touched in a specific area is a more obvious signal. The AAHA notes that painful pets may be frightened or confused about what they are feeling and may become more vocal, particularly during physical interaction.
Grooming behaviour changes
A dog that suddenly begins obsessively licking or chewing a specific area of its body, a joint, a paw, a spot on the back is often attempting to self-soothe a painful area. Conversely, a dog that stops grooming or avoids being touched around a specific area is guarding it from discomfort.
Physical signs of pain in cats
Cats are more effective at hiding pain than dogs. The Merck Veterinary Manual notes that even cats that are clearly unwell may continue certain normal behaviours, eating occasionally, grooming selectively, greeting owners while concealing significant discomfort. Changes in their normal behaviour pattern, rather than specific pain actions, are the most reliable indicators.
Knowing how to identify pain in dogs cats is especially important with cats because their changes in normal behaviour can be extremely subtle.
Activity and movement changes in cats
- Reluctance to jump onto surfaces they normally use without hesitation
- Jumping onto furniture in stages rather than in one smooth movement
- Reduced overall movement and increased time spent resting
- Choosing lower sleeping positions than usual avoiding high perches
- Difficulty grooming the mid-back or base of tail unable to reach comfortably
Litter box behaviour
A cat in pain that finds climbing into a litter box uncomfortable may urinate or defecate outside it. This is frequently misread as a behavioural problem when it is actually a pain response particularly if the litter box has high sides or requires a step to enter. Texas A&M’s veterinary school specifically notes that cats with chronic pain may use the litter box less often, especially if it has a high rim to climb over.
Any change in litter box habits should be investigated medically before being treated as a behaviour issue.
Facial and body posture in cats
Cats in pain often sit with their feet tucked under their body rather than relaxed. They may curl tighter than usual or, conversely, lie stretched out in positions they do not normally adopt. Head down with ears slightly back or flat is a pain signal in cats. Dilated pupils without excitement or fear context can also indicate pain.
Behavioural signs common to both dogs and cats
Changes in social behaviour
A pet that was previously social and is now withdrawn, hiding, or avoiding family members is showing a significant behavioural change. Similarly, a pet that has always been independent and suddenly becomes excessively clingy may be seeking reassurance that something is wrong. Cedarwood Veterinary Hospital notes that this emotional change is particularly common in cats, who may become reclusive or exhibit uncharacteristic behaviour when in pain.
Changes in appetite and grooming
Both increased and decreased appetite can accompany pain, depending on the source. A cat that approaches the food bowl but doesn’t eat, or a dog that seems interested in food but turns away, may be experiencing pain that makes eating uncomfortable, particularly dental or abdominal pain.
Reduced grooming or selective grooming in a cat that was previously fastidious is a meaningful signal. Excessive grooming of a specific spot in either species indicates localised discomfort.
Aggression or uncharacteristic snapping
A dog or cat that snaps, bites, or growls when touched in an area they previously allowed or a pet that has never shown aggression and suddenly does is often communicating pain through the only language available to them. This is a particularly important context: uncharacteristic aggression should prompt a pain assessment, not a behavioural correction.
Recognising these behavioural changes can help show how AI help detect pet health problems when multiple signs are assessed together.
When to act
| Any combination of two or more of these signs — particularly if they have appeared recently or are getting worse — warrants a vet appointment. Do not wait for the pain to become obvious. By that point, the treatment is more complex and the cost is higher. |
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If you are unsure whether what you are observing represents pain or just an off day, PetCare AI’s AI Vet can help you work through the specific combination of signs, species, age, and context included and return a structured assessment of likely severity and recommended next steps.
Tools like AI Vet can support owners who want to understand how AI help detect pet health problems, but they should complement rather than replace professional veterinary assessment.