When degenerative myelopathy reaches the chest and neck, breathing becomes part of the disease — and that changes everything a caregiver needs to watch for.

Quick answer: In late-stage degenerative myelopathy, the disease can progress far enough up the spinal cord to weaken the muscles that control breathing. DM breathing problems typically appear after a dog has already lost the use of all four limbs and include labored breathing at rest, a visibly changed breathing pattern, and increasing reliance on abdominal muscles to draw each breath. These signs are generally considered a marker of end-stage DM. There is no treatment that reverses the underlying muscle weakness, but positioning, comfort care, and honest quality-of-life conversations with your veterinarian can guide what comes next.

Most caregivers know the DM timeline from the back end: hind-leg weakness, then knuckling, then paralysis, then loss of bladder and bowel control. What the typical DM guide doesn’t prepare you for is what happens when the disease continues past that point. If a dog lives long enough — and is strong enough, or cared-for carefully enough — DM doesn’t stop at the hindquarters.

This article is specifically for caregivers who are already in late-stage care, or who are trying to understand what late-stage DM actually looks like as it progresses toward the end. It’s a hard topic, and I want to be direct with you about it.

How Does DM Eventually Affect Breathing?

Degenerative myelopathy is a disease of the spinal cord. It begins in the thoracolumbar region (the lower back and mid-back) and, if it continues, travels upward. When it reaches the thoracic spinal cord segments that control the intercostal muscles (the muscles between the ribs) and eventually the cervical segments that influence the diaphragm, breathing becomes compromised.

This is called upper motor neuron involvement in the respiratory system. The nerve signals that coordinate breathing muscles weaken or fail to transmit reliably. The dog’s body shifts its breathing effort to whatever compensatory muscles it can still recruit, most often the abdominal muscles.

The Merck Veterinary Manual notes that DM is a progressive upper motor neuron disease affecting the spinal cord, and that in advanced cases the disease can involve the thoracic limbs, trunk, and beyond. The respiratory consequences are an extension of the same degenerative process that took the hindlimbs first.

This doesn’t happen to every dog with DM. Many families reach a point, well before respiratory involvement, where quality of life has declined enough that they choose humane euthanasia. Respiratory signs are what you encounter when a dog has progressed through every earlier stage and is now in the final chapter. If you’re reading this, you may be living through exactly that.

What Are the Signs of DM Breathing Problems?

The early signs of respiratory decline in a late-stage DM dog are easy to miss because they develop gradually and because dogs are remarkably adaptive. What you are looking for is any change from your dog’s established resting breathing pattern.

Labored breathing at rest: Your dog appears to be working to breathe even when lying still and calm. You may see the ribcage moving more deeply or effortfully than usual, or notice the belly pumping visibly with each breath.

Abdominal breathing: Healthy dogs primarily breathe with their chest. When intercostal muscles weaken, the abdomen begins doing much of the work. Watch for the belly rising and falling more dramatically than the chest.

Altered breathing rhythm: A change in rate (faster or slower than normal), or a pattern that seems inconsistent — a breath that seems to stall, or one that’s noticeably shallower than the one before it.

Audible breathing at rest: Breathing that has become noisy, raspy, or effortful-sounding when the dog is calm and not panting. This is distinct from normal panting after exertion.

Open-mouth breathing without exertion: A dog who is resting quietly but breathing with an open mouth may be struggling to get enough air through normal nasal breathing.

Sleep-related changes: Irregular breathing during sleep, or appearing to wake suddenly and struggle to settle breathing back into a normal rhythm.

Changes to Watch For
  • Breathing that looks effortful when your dog is lying still and calm
  • The belly working harder than the chest during each breath
  • Any new audible quality to resting breaths
  • Open-mouth breathing without heat, exercise, or anxiety as a cause
  • Changes in sleep breathing patterns

Why This Is Different From Other Breathing Issues

It’s worth pausing here, because not every breathing change in a late-stage DM dog is caused by the DM itself. A dog who is non-ambulatory and spending most of their time recumbent (lying down) is at higher risk for several conditions that also cause breathing changes.

Pneumonia (aspiration pneumonia): Dogs who cannot reposition themselves are more prone to inhaling small amounts of food or liquid. Aspiration pneumonia causes breathing changes, fever, and lethargy and is a distinct, treatable condition. If breathing changes come on suddenly or are accompanied by fever or worsening quickly, call your vet the same day.

Heart disease: Many dogs of the age at which DM presents also develop age-related heart conditions. An enlarged heart or fluid accumulation can cause labored breathing that mimics respiratory muscle weakness.

Anxiety and pain: A dog experiencing pain or distress may breathe faster or appear to breathe more shallowly. This is worth ruling out separately before attributing all breathing changes to DM progression.

Your veterinarian can help distinguish between these. The reason it matters: some of these causes are treatable, and a dog whose breathing is compromised by pneumonia rather than late-stage DM is in a different situation than one whose spinal cord disease has finally reached the respiratory system.

Other Causes to Rule Out
  • Aspiration pneumonia (treatable — warrants a same-day vet call)
  • Heart disease with fluid accumulation
  • Pain or anxiety driving faster, shallower breathing
  • Obesity compressing the chest in a dog who can no longer move

What Does This Signal About Where You Are in the Disease?

Respiratory involvement is widely considered a marker of end-stage DM. A dog who has already lost all four-limb function and bladder and bowel control, and who is now showing dm breathing problems, is in a significantly advanced state of disease.

I want to say this gently but clearly: this is the point at which most veterinary neurologists and experienced DM caregivers will suggest a serious quality-of-life conversation. Not because the dog is in pain from DM itself (the disease is not painful in the way that IVDD or arthritis is painful), but because the dog’s ability to do the most basic thing — breathe comfortably — is now compromised.

The DM progression timeline varies by individual dog, but respiratory involvement tends to signal that there is limited time remaining regardless of what care is provided. There is no medication, surgery, or therapy that reverses the spinal cord degeneration that is causing the breathing changes.

That said, “limited time remaining” is not a specific number. Some dogs decline rapidly from this point; others plateau for a period. Only your veterinarian, who can examine your dog, can give you the most honest picture of where things stand.

How Can You Support a Dog With DM Breathing Problems?

Even without a cure, there is meaningful care you can offer.

Positioning: This is the single most practical thing you can do. A dog lying flat on their side has more compressed lung capacity than one propped with a thick foam wedge at a slight incline. Many owners in the DM caregiving community find that propping the dog’s chest slightly elevated reduces visible breathing effort. Rotating position regularly (every two to four hours) also helps prevent the dependent lung from becoming compromised by prolonged pressure.

Keep the environment cool: Heat increases respiratory rate and effort. A dog struggling to breathe should never be in a warm or stuffy room. Fans, air conditioning, and cool surfaces help.

Minimize physical and emotional stress: Stress drives faster breathing. A calm, quiet environment where your dog feels secure helps keep their breathing as easy as possible.

Monitor consistently: Keep a simple log of breathing rate at rest (count breaths per minute for a full minute when your dog is relaxed and asleep). A normal resting respiratory rate in dogs is generally under 30 breaths per minute. A rate consistently above that, or trending upward over days, is useful information to share with your vet.

Ask about comfort care options: If your dog appears distressed by breathing difficulty, your veterinarian may be able to discuss options that reduce the subjective distress without altering the underlying progression.

Practical Support Measures
  • Prop the chest at a slight incline using a foam wedge or rolled blankets
  • Rotate body position every 2–4 hours to protect both lungs
  • Log resting respiratory rate (breaths per minute when sleeping)
  • Keep the room cool and calm
  • Share your breathing observations with your vet at every check-in

Caregiver Decisions When Respiratory Signs Appear

This is where the article has to get honest in a different way, because information alone won’t carry you through this part.

Respiratory involvement in DM tends to force the quality-of-life conversation that many caregivers have been holding in the background. For a thorough framework on thinking through that conversation, the quality-of-life assessment for DM dogs is worth reading carefully. And if you haven’t yet, the end-of-life planning guide for DM dogs covers the practical decisions that come next.

What many DM caregivers describe — and what veterinary neurologists often gently confirm — is that breathing changes are a signal that the body is working very hard just to keep going. The DM community I’ve listened to over the years consistently says: watching a dog labor to breathe, when you cannot make that easier, is one of the clearest guides to knowing it’s time.

That is not a clinical statement. It’s a human one. And it matters as much as any medical marker.

When to Call Your Vet Today
  • Breathing rate at rest is consistently above 30 breaths per minute
  • Breathing appears distressed, not just effortful
  • Open-mouth breathing at rest with no heat or excitement as a cause
  • Sudden worsening rather than gradual change (may indicate aspiration pneumonia or another treatable cause)
  • Your gut tells you your dog is struggling in a way they cannot recover from

There is no right answer to how long you continue, and I won’t pretend there is. What I can say is that naming what is happening — that DM has reached your dog’s ability to breathe — is not giving up. It is seeing your dog clearly. And that clarity, as hard as it is, is one of the most loving things you can offer.

Frequently Asked Questions

Does degenerative myelopathy always cause breathing problems?

Not every dog with DM lives long enough to develop respiratory signs. Breathing problems tend to emerge in the most advanced stages, when the disease has progressed from the hindquarters into the thoracic and eventually cervical spinal cord. Some dogs reach this stage; many do not, because caregivers choose end-of-life care earlier in the disease course.

What does abnormal breathing look like in a late-stage DM dog?

The most commonly reported changes are labored or effortful breathing at rest, a noticeable shift in breathing rhythm, increased reliance on the belly and abdominal muscles to breathe, and an audible quality to each breath. Some dogs develop a shallow, rapid pattern; others breathe slowly but with visible effort. Any change from your dog’s normal resting breathing pattern warrants a veterinary conversation.

How long after breathing problems start does a DM dog have?

There is no reliable timeline. Respiratory decline in DM is variable, and progression can be slow or fast depending on the individual dog. Many veterinary neurologists consider the onset of respiratory signs to be a significant marker for quality-of-life discussions, but it does not define a specific endpoint.

Is there anything that helps a DM dog with breathing difficulty?

Positioning matters more than people realize — propped on a thick foam wedge rather than lying flat can reduce breathing effort for some dogs. Minimizing stress, keeping the environment cool, and avoiding overexertion are also widely recommended. There is no medication that reverses DM-related respiratory muscle weakness, but comfort-focused care can support quality of life while it remains meaningful.

This guide is based on real experience and should be used alongside professional veterinary care. Always consult your veterinarian before starting any new treatment or making changes to your dog’s care plan.