Progressive myelomalacia after IVDD: what it means and what to watch for

First, three terms you may hear at the hospital

Veterinary teams often use several similar-looking abbreviations. They do not all mean the same thing.

What actually happens in progressive myelomalacia?

In PMM, tissue inside the spinal cord becomes severely damaged and that damage extends beyond the area first injured by the disc. Veterinary papers describe bleeding, loss of blood supply and tissue death spreading up and/or down the spinal cord.¹

Owners do not need to recognise those microscopic changes themselves. The practical concern is whether a dog's neurological function keeps getting worse instead of remaining stable after the original injury.

When can it happen?

PMM is usually seen in the days after a severe disc injury. Published veterinary guidance describes cases beginning from about 24 hours after the injury through to around 14 days later, and it may not be obvious when a dog first reaches hospital.¹

In one large clinical series, most affected dogs developed recognisable signs within two days of presentation, although later cases also occurred.² This is why repeated neurological examinations can matter so much in severely affected dogs.

Which dogs are at higher risk?

The strongest risk factor is the severity of the original spinal cord injury. Dogs who cannot move their back legs and have lost deep pain sensation are at higher risk than dogs with milder neurological injury. Even then, loss of deep pain does not mean a dog automatically has or will develop PMM.²

French Bulldogs have been associated with a higher risk in some studies, but breed alone cannot predict what will happen to an individual dog.^{3 4}

What changes are veterinary teams looking for?

These are neurological findings that need professional interpretation. They are included here so owners understand what the hospital may be monitoring — not so they can try to diagnose PMM themselves.

Why repeat checks matter

A dog can look stable at the first examination and then change later. PMM may evolve after the initial neurological assessment or imaging, so repeated examinations are important when a specialist believes a dog is at meaningful risk.²

The important question is not simply “Can my dog walk yet?” It is whether neurological function is stable, improving or continuing to worsen.

Questions worth asking your neurologist

• Do you consider my dog to be at meaningful risk of progressive myelomalacia?
• Which neurological changes are you monitoring?
• What changes should I watch for after discharge?
• For how long do you want particularly close monitoring?
• Which changes mean I should return to hospital immediately?
• How will you distinguish expected recovery from progressive deterioration?

Frequently asked questions