Key Takeaways
- Animals instinctively hide pain, so subtle behavioural changes are often the earliest signal.
- Vets use validated pain scales tailored to specific species to score discomfort objectively.
- Facial grimace scales have become a reliable tool for assessing pain in cats, mice, and rabbits.
- Physiological signs like elevated heart rate and blood pressure support but do not replace behavioural assessment.
- Owners who track changes at home give vets the most useful data for pain evaluation.
What you will need
Why animals conceal pain
Most mammals are prey species in evolutionary terms, or share ancestors who were. Displaying weakness or vulnerability in the wild carries real risk, so animals have developed strong instincts to suppress visible signs of pain. Domestic cats, rabbits, and even dogs continue to mask discomfort long after the original survival pressure is gone. By the time a pet shows obvious signs of pain, the condition has often been present for some time.
This instinct creates a genuine challenge for both owners and veterinarians. Unlike a human patient who can point to a location, rate pain on a numeric scale, and describe its character, an animal communicates only through changes in behaviour, posture, and physiological state. Recognising what those changes look like is the foundation of veterinary pain assessment.
Owners who know their animal's normal baseline have a significant advantage. Small deviations from that baseline, things like a cat sleeping in a new spot, a dog hesitating before lying down, or a rabbit spending less time at the food bowl, are often the first signal that something is wrong. See our article on dental warning signs for an example of how subtle behavioural shifts can point to conditions that are easy to miss.
Keep a short behaviour diary
Before a vet appointment, jot down specific changes you have noticed: when they started, how often they occur, and whether anything seems to worsen or ease them. A dated record of changes in appetite, movement, or social behaviour gives your vet far more to work with than a general impression. Even a few notes on your phone can make a real difference during a short clinic visit.
How veterinarians structure a pain assessment
A systematic pain assessment combines owner-reported history, direct observation before handling, structured scoring with a validated pain scale, physiological measurements, and hands-on physical examination. No single element is sufficient on its own; the reliability of the assessment depends on how well these sources of information fit together.
The steps below describe how this process typically unfolds, and what owners can do to make each stage more informative. Pain assessment is also not a single event: repeat scoring across a visit or across multiple visits allows vets to track changes and evaluate whether treatment is helping. Body condition scoring is another area where multi-tool assessment gives a more accurate picture than any single measure, and the logic is similar here.
What you will need
Observe posture and movement at rest
Veterinarians begin by watching how the animal holds its body when it is not being handled. A hunched posture, reluctance to lie down, abnormal weight distribution across limbs, and a tucked abdomen are all posture signals worth noting. In cats, a loaf position with forelimbs tucked tightly under the body can indicate abdominal or musculoskeletal discomfort. Dogs may shift weight off a sore limb even when standing still.
At home, owners can notice whether the pet struggles to rise from rest, avoids stairs or furniture it usually climbs, or favours one side when walking.
Assess facial expressions with a grimace scale
Facial grimace scales are validated tools used across several species, including cats (the Feline Grimace Scale), rabbits, mice, and horses. Each scale scores specific action units: orbital tightening (squinting), changes to ear position, whisker or muzzle tension, and head position relative to the shoulders.
A cat in pain typically shows partially closed eyes, ears rotated outward and flattened, tense cheek and muzzle muscles, and a head carried lower than normal. These signs are subtle and easy to miss without knowing what to look for, which is why trained observers using a structured scale produce more consistent results than informal impressions alone.
Apply a structured pain scoring scale
Beyond facial cues, veterinary clinics use composite pain scales that combine multiple domains into a single numeric score. The Glasgow Composite Measure Pain Scale (short form) is widely used for dogs and covers vocalisation, attention to wound or painful area, mobility, response to touch, and demeanour. Similar multi-domain tools exist for cats and for horses.
Scoring at intake and again after treatment lets the veterinary team measure whether an intervention is working and adjust the approach accordingly. A score that does not improve after analgesia prompts reassessment of both the diagnosis and the treatment plan.
Measure physiological indicators
Heart rate, respiratory rate, blood pressure, and pupil dilation can all shift in response to pain. These measurements are collected during a physical examination and compared against normal ranges for the species, breed, age, and size of the animal. Elevated values support a pain assessment, but they are not specific: stress, fear, and illness can produce identical readings.
This is why physiological data is interpreted alongside behavioural findings rather than used alone. An animal that reads as calm but has a markedly elevated heart rate warrants further investigation rather than a reassurance that nothing is wrong.
Conduct palpation and movement testing
Hands-on examination lets the vet identify the source and severity of pain more precisely. Gentle, systematic pressure applied to specific anatomical regions reveals localised tenderness: a flinch, muscle tension, vocalisation, or attempt to move away from touch are all clinically significant responses. Range-of-motion testing of joints and limbs identifies stiffness or pain that only appears under load.
In animals that are particularly defensive or fearful, the vet may recommend mild sedation to allow accurate assessment without adding distress. A guarded or aggressive response to handling is itself a pain signal, not just a temperament issue.
Report your home observations clearly
Your account of what the animal does at home over days or weeks is information the vet cannot collect during a 20-minute appointment. Describe specific behaviours rather than general impressions: "she stopped jumping onto the sofa three weeks ago" is more useful than "she seems a bit slow." Note changes in appetite, water intake, grooming, play, sleep location, and social interaction.
Pets with chronic pain often show gradual changes that owners attribute to normal ageing, including reduced activity and altered sleep patterns. Reporting these changes early, rather than waiting for an obvious sign, gives vets a better chance of identifying and managing discomfort before it worsens. See our guide to making the most of annual check-ups for practical advice on preparing for these conversations.
This article is general information only
The content here describes how veterinary professionals evaluate pain as a general educational overview. It is not a substitute for a professional veterinary assessment. If you suspect your pet is in pain, contact your veterinarian promptly rather than attempting to diagnose or treat the animal at home.