What is myelomalacia, and what does it mean for a dog with IVDD?

A rare complication

If you are reading this, someone may have said the word "myelomalacia" to you, or you came across it while reading about IVDD late at night. It is a frightening word, and it is natural to want to understand it.

The short answer: myelomalacia is a rare but serious complication that can follow a severe disc injury. It means the spinal cord itself has been badly damaged, and in some dogs that damage keeps spreading along the cord over the following days. Vets sometimes call it progressive myelomalacia, or ascending/descending myelomalacia.

The most important thing to know first: it is rare, and it is very rare in dogs who can still feel deep pain. If your vet has told you your dog still has deep pain sensation, myelomalacia is very unlikely for your dog. It is mainly discussed with families whose dog has lost the use of their back legs and can no longer feel deep pain, and even in that group, most dogs do not develop it.

Only the team examining your dog can tell you whether your dog is at risk.

Act now first

If your dog suddenly cannot walk, is dragging or knuckling legs, cannot pee or is leaking without knowing, cries out in pain you cannot settle, or is getting worse over hours, get to your vet or an emergency hospital now. Fast care matters most for the disc injury itself. See IVDD emergency signs and the first 24 hours.

If your dog is already in the hospital or home after a severe injury and something changes, such as new weakness in the front legs, breathing that looks different, or your dog suddenly seeming very unwell, call your vet right away.

What myelomalacia means

"Myelo" refers to the spinal cord, and "malacia" means softening. With IVDD, disc material can hit or press on the spinal cord. Most of the time, the cord is bruised and squeezed, and it can heal over time with rest or surgery.

In a small number of severe injuries, the cord is hurt so badly that the damaged area does not settle. Instead, the injury can spread up and down the cord over several days, beyond the disc that started it. That spreading is what vets mean by progressive myelomalacia.

It is a complication of the injury itself. Researchers are still learning why it happens in some dogs and not in others.

Why deep pain sensation matters so much

Deep pain sensation means your dog consciously feels a firm pinch to a toe, not just pulls the foot away by reflex. It is one of the most important things a vet checks after a disc injury. See severity grades.

• Dogs who can still walk, even wobbly: myelomalacia is extremely rare.
• Dogs who cannot walk but still move their legs or feel deep pain: it is rare.
• Dogs who are paralyzed in the back legs and cannot feel deep pain: this is the group vets watch most closely. It is still not the most common outcome, even here.

Please do not test deep pain at home. Repeated pinching can bruise your dog and confuse the picture. Leave it to your vet or neurologist.

What vets watch for

When a dog has a severe injury, the team usually keeps a close eye on them for the first several days, because if myelomalacia is going to happen, it most often shows up early. These checks happen in the clinic. You do not need to do them at home. They may include:

• whether the area where your dog can feel the skin twitch is moving further up the body
• whether the back legs and tail become very floppy and reflexes fade
• whether the belly muscles seem weaker
• whether the front legs start to weaken
• changes in breathing
• your dog seeming generally unwell, quiet, off food, or warm to the touch, or having pain that is hard to settle

None of these signs on its own means myelomalacia. Many have other causes. Your vet puts the whole picture together, often over repeated exams. An MRI can sometimes show changes that raise concern, but the pattern over time usually matters most. See diagnosis.

What some studies found in the most severe group

Many families ask how likely it is. Numbers from research describe groups of dogs, not your dog. Your vet knows your dog's situation.

One large study looked back at 652 dogs who had surgery for a disc in the back. Here is how often presumed myelomalacia was seen, grouped by how each dog was doing when first seen:

Source: Balducci et al. 2017, Journal of Veterinary Internal Medicine. Grading systems differ between hospitals, so ask your vet how they describe your dog.

Other studies of dogs in that most severe group, paralyzed with no deep pain, have reported figures from about 9% to 17.5% (Castel et al. 2017 and 2019).

What this means:

• For dogs who still feel deep pain, it is rare. In this study, it was 2.7% or lower.
• Even in the most severe group, most dogs did not develop it. In this study, most dogs in this group did not.
• These studies looked at dogs with back (thoracolumbar) disc injuries. Ask your vet what applies to your dog, especially if the injury is in the neck. See neck (cervical) IVDD.

Researchers have also looked at which features may raise the risk, such as a disc in the lower part of the back and signs that came on very fast. These are patterns in groups, not predictions. Your vet can tell you whether any apply to your dog.

If your dog has lost deep pain

Hearing that your dog cannot feel deep pain is one of the hardest moments in IVDD. It does not mean your dog will develop myelomalacia, and it does not mean your dog cannot have a good life. Some dogs regain walking. Many dogs who stay paralyzed live full, happy lives with good bladder care, skin care, and help getting around. See mobility aids and bladder care.

Families often find it helps to hear from others who have been there. Moo's story follows a French Bulldog whose IVDD left her with lasting changes. Today she wears diapers and little shoes, rides in a stroller, and in her owner's words may be even happier. More family stories are on our stories page.

Your vet may talk with you about options such as surgery, and about how closely your dog will be watched in the first days. See IVDD surgery, surgery vs conservative care, and GP vet vs neurologist. Medicines, when used, are chosen by your vet; see IVDD medications for medicine types, and do not start, stop, or change any medicine or supplement on your own.

If your vet is worried about myelomalacia

In rare circumstances, a family may be told their dog has myelomalacia or is likely developing it. If that happens to you, your vet will talk with you about what it means for your dog. Some families may need to explore difficult decisions. Those decisions are serious, and they are best made together, with your family, your friends, and your veterinarian. Tendi does not guide you one way or the other.

Whatever you are facing, you do not have to carry it alone. See caring for yourself as a caregiver.

Questions to ask your vet

• Can my dog still feel deep pain? Will you check again?
• Is myelomalacia something you are watching for in my dog, or is it unlikely?
• How closely will my dog be watched over the next few days?
• Which changes would mean I should call you right away?
• Is the injury in the back or the neck, and does that change anything?
• Would an MRI or a neurologist add anything right now? See questions before an MRI.
• If my dog stays paralyzed, what support would help us at home?

Before you decide anything

This guide is educational. A veterinarian who can examine your dog should make diagnosis and treatment decisions. Tendi does not diagnose, treat, or cure disease.