Understanding IVDD

IVDD Stages & Grades Explained: What the Numbers Really Mean

If a vet says “grade 3”, “stage 4” or “deep pain negative”, the number can sound frightening. The most useful question is not “what number is my dog?” but “what can my dog actually do, and is that changing?” Different veterinary teams and research papers can use different grading systems, so the number only makes sense when the scale is explained.12

Evidence-informed guideBased on peer-reviewed canine spinal-cord injury literature and the 2022 ACVIM consensus statement. Sources are listed after the medical disclaimer →
Aubenord visual guide showing five levels of IVDD neurological severity, from pain while still walking to paralysis with deep pain absent.
Aubenord's plain-English severity guide. It is designed to help owners understand the words a veterinary team may use. It is not a universal grading scale, and deep pain should only be assessed by a veterinary professional.
If your dog is getting weaker, suddenly cannot walk, loses movement in the legs or develops new bladder problems, seek urgent veterinary assessment. Do not wait to work out a grade at home.

Start with what your dog can actually do

Veterinary neurologists describe severity by looking at function: whether a dog can walk, whether voluntary movement is still present, and — in severely affected dogs — whether deep pain perception is present.1

These five levels are an owner-friendly explanation, not a universal veterinary numbering system. They help translate clinical language into everyday observations.
1. Pain, but still walking normallyYour dog may have back or neck pain, stiffness, trembling or a guarded posture, but you are not seeing an obvious walking problem.
2. Walking, but weak or wobblyYour dog can still walk without support, but may sway, cross the feet, scuff nails, knuckle or look weaker than normal.
3. Cannot walk without supportYour dog may still move the legs voluntarily, but cannot take normal unsupported steps or stand and walk independently.
4. Paralysed, but deep pain is presentVoluntary movement in the affected legs is absent, but a veterinary neurological examination still finds conscious deep pain perception.
5. Paralysed and deep pain is absentA veterinarian cannot identify conscious deep pain perception. This is a severe neurological finding and needs urgent specialist-level assessment.
Why Aubenord describes function first: two vets can use different numbering systems and still be describing the same neurological state. “Can walk”, “cannot walk”, “paralysed”, and “deep pain present or absent” are much more useful than a number on its own.

Why can “grade 5” mean different things?

This is the part that causes most confusion. Some published IVDD scales count upwards as severity increases. Other spinal-cord injury scales run in the opposite direction. That means a high number can represent severe disease in one system and a much milder state in another.23

Example: a scale that counts upwards

In one commonly cited modified Frankel convention used in canine IVDD research, the numbers progress from milder to more severe neurological loss.

1 = pain only→5 = paralysis + deep pain absent

Other scales may count the other way

Some spinal-cord injury systems arrange the most severe neurological state at the low-number end and better function at the high-number end.

lower number = more severe→higher number = better function
So if someone tells you “your dog is grade 4”, ask one simple question:
“Which grading scale are you using, and what does that mean for my dog's walking, voluntary movement and deep pain perception?”

What does “deep pain positive” or “deep pain negative” mean?

Deep pain perception is a conscious response to a painful stimulus during a veterinary neurological examination. A leg pulling away on its own is only a reflex and does not necessarily prove that the dog consciously felt the stimulus.1

Do not test deep pain at home. Do not pinch toes, squeeze nails or use painful stimuli yourself. Deep pain testing can be difficult even for professionals and should be performed by a veterinarian or veterinary neurologist.

What matters more than the number?

Can your dog walk?Walking independently versus needing support is one of the clearest functional differences.
Can your dog move the legs voluntarily?Voluntary movement is different from a reflex movement.
Are signs improving, stable or worsening?The direction of change can matter as much as the label at one point in time.
What did the veterinary examination find?Deep pain status, spinal location, imaging findings and the overall neurological examination all contribute to decisions.

The 2022 ACVIM consensus statement groups dogs by functional neurological status — such as ambulatory versus non-ambulatory weakness, paralysis and deep-pain status — because these distinctions help guide management and prognosis.4

If your vet gives you a grade, ask what it means in plain English

  • Which grading scale are you using?
  • Can my dog still walk independently?
  • Can my dog still move the affected legs voluntarily?
  • Is deep pain perception present?
  • Are the neurological signs stable, improving or progressing?
  • Does this change your recommendation for MRI/CT, referral or surgery?
  • What change should make me contact you urgently?

Choose what you need next

Understand deep pain

What “deep pain positive” and “deep pain negative” mean — without trying to test it yourself.

Deep pain explained
If your dog is worsening

Use the emergency guide for sudden loss of walking, rapid deterioration or severe neurological change.

Emergency signs
If diagnosis or treatment is being discussed

Understand advanced imaging, surgery and referral options.

MRI guideSurgery guide

Frequently asked questions

Is grade 5 always the worst IVDD grade?

No. It depends on the grading system. In some scales a higher number means more severe neurological loss; in others the direction is reversed. Ask what the number means in terms of walking, voluntary movement and deep pain.

What is the difference between deep pain positive and deep pain negative?

Deep pain positive means a veterinary professional identifies a conscious behavioural response to a painful stimulus. Deep pain negative means that conscious response cannot be identified. A simple withdrawal reflex is not the same thing.

Can an IVDD grade change?

Yes. Neurological status can improve or worsen, which is why veterinary teams may reassess a dog repeatedly rather than relying on one examination or one number.

Should I try to grade my dog at home?

No. You can describe what you see — for example wobbling, dragging, falling or inability to walk — but neurological grading and deep pain assessment should be done by a veterinary professional.

Medical safety note: this guide is educational. It cannot diagnose IVDD, assign your dog's neurological grade, test deep pain or tell you which treatment is appropriate. New or worsening neurological signs need veterinary assessment.

Trust & safety

Medical limitations & how this guide is prepared

Different veterinary teams and research papers can use different grading systems. This guide translates common neurological language but cannot grade your dog or test deep pain perception.

Function matters more than the number

Walking ability, voluntary movement, progression and professionally assessed deep pain status are more useful than a grade number without its scale.

How this content is researched

Aubenord uses peer-reviewed veterinary literature and specialist consensus guidance, with differences between grading systems stated clearly.

Editorial standardsMedical disclaimer

Evidence base

Sources & further reading

Evidence limit: a grading framework describes neurological status; it does not by itself determine treatment or an individual prognosis.