Introduction: When IVDD Becomes a Progressive Spinal Cord Catastrophe

Intervertebral Disc Disease (IVDD) is common in Dachshunds and, in most cases, manageable with timely medical or surgical intervention. However, in a small but devastating subset of severe spinal cord injuries, IVDD may trigger a progressive and often fatal complication known as myelomalacia.

Myelomalacia refers to hemorrhagic necrosis of the spinal cord, characterized by progressive softening and destruction of neural tissue. In Dachshunds—already predisposed to acute Hansen Type I disc extrusion—the risk of myelomalacia is closely linked to the severity of the initial spinal cord insult.

Early recognition of this condition is critical, as progression can be rapid and prognosis grave. This article explores myelomalacia in Dachshunds from a pathophysiological, neurological, and clinical management perspective, with emphasis on early warning signs and outcome expectations.

What Is Myelomalacia?

Definition

Myelomalacia is a progressive ischemic and hemorrhagic necrosis of the spinal cord that may extend cranially, caudally, or in both directions from the site of primary injury.

It most commonly develops following:

• Severe acute disc extrusion

• Traumatic spinal cord injury

• Profound vascular compromise

In Dachshunds, the most frequent trigger is acute thoracolumbar Hansen Type I disc extrusion with severe contusive injury.

Pathophysiology: How Does Myelomalacia Develop?

Primary Injury

The process begins with a severe mechanical insult:

• Sudden extrusion of mineralized disc material

• High-velocity impact against the spinal cord

• Compression combined with contusion

This causes:

• Direct neuronal damage

• Disruption of axonal tracts

• Microvascular rupture

Secondary Injury Cascade

Following the initial trauma, a complex cascade unfolds:

• Spinal cord edema

• Reduced perfusion and ischemia

• Release of inflammatory cytokines

• Oxidative stress

• Excitotoxic neurotransmitter release

• Apoptosis and necrosis

When perfusion is not restored and inflammatory injury progresses, spinal cord tissue begins to liquefy, resulting in progressive myelomalacia.

Progressive Ascending and Descending Necrosis

Unlike focal spinal cord compression, myelomalacia can extend beyond the original injury site:

• Ascending myelomalacia progresses cranially toward the cervical spinal cord.

• Descending myelomalacia spreads caudally toward the lumbar and sacral regions.

Ascending progression is particularly concerning because it can ultimately affect respiratory centers.

Why Dachshunds Are at Elevated Risk

Severe Hansen Type I Extrusions

Dachshunds are predisposed to explosive disc extrusions due to:

• Premature disc mineralization

• Structural disc brittleness

• High intradiscal pressure

These extrusions often occur with significant concussive force, increasing risk of contusive spinal cord injury—one of the main drivers of myelomalacia.

High Incidence of Deep Pain-Negative Injuries

Dogs that present without deep pain perception are at significantly higher risk for developing myelomalacia. Dachshunds, being overrepresented among severe IVDD cases, consequently represent a substantial proportion of myelomalacia cases.

Clinical Presentation: Early Recognition

Early identification is essential but challenging. Myelomalacia typically develops within:

• 24–72 hours after injury

• Occasionally up to 5–7 days post-operatively

Early Warning Signs

In Dachshunds that are already paraplegic, the following signs may suggest progression:

• Loss of previously intact spinal reflexes

• Decreasing pelvic limb tone

• Progressive cranial migration of the cutaneous trunci reflex cutoff

• Increasing flaccidity

• Worsening pain on palpation beyond initial lesion site

Cutaneous Trunci Reflex as a Monitoring Tool

The cutaneous trunci reflex (panniculus reflex) is particularly useful.

In thoracolumbar IVDD:

• A distinct “cutoff” point typically corresponds to the lesion location.

• Cranial migration of this cutoff suggests ascending necrosis.

Serial neurological exams are critical in high-risk Dachshunds.

Advanced Signs of Progressive Myelomalacia

As the condition advances:

• Abdominal tone decreases

• Loss of anal tone

• Complete areflexia

• Hypothermia

• Signs of systemic shock

If ascending progression reaches the cervical spinal cord:

• Thoracic limb weakness

• Reduced thoracic limb reflexes

• Respiratory compromise

Respiratory failure is often the terminal event in ascending myelomalacia.

Diagnostic Limitations

MRI Findings

MRI may show:

• Extensive T2-weighted hyperintensity

• Spinal cord swelling

• Loss of gray-white differentiation

However, imaging cannot always reliably predict progression.

Definitive Diagnosis

Definitive confirmation is histopathologic, meaning diagnosis is often presumptive based on:

• Clinical progression

• Neurological deterioration

• Lack of response to decompression

Prognosis

In Deep Pain-Positive Dogs

Myelomalacia is rare when deep pain perception is intact.

In Deep Pain-Negative Dachshunds

Risk is significantly higher, with reported incidence ranging from approximately 9–17% in severe cases, depending on study population.

Once progressive myelomalacia is clinically apparent, prognosis is grave.

There is currently:

• No effective treatment to reverse established myelomalacia

• No proven pharmacologic intervention that halts progression

Outcome is typically fatal.

Surgical Considerations and Risk

Hemilaminectomy relieves compression but does not eliminate risk of myelomalacia if:

• Severe contusive injury has already occurred

• Secondary injury cascade is advanced

Surgery may reduce ongoing compression but cannot reverse established necrosis.

Ethical and Clinical Decision-Making

Early recognition allows for:

• Honest prognostic discussions

• Avoidance of prolonged suffering

• Appropriate end-of-life planning

Because progression may occur post-operatively, owners must be counseled prior to surgery regarding:

• Risk of myelomalacia

• Signs to monitor

• Expected timelines

Clear communication is essential.

Prevention: Is It Possible?

There is no direct preventive measure for myelomalacia itself. However, reducing severity of initial IVDD episodes may indirectly reduce risk.

Preventive strategies include:

• Early intervention for back pain

• Strict activity restriction at first neurological signs

• Weight management

• Environmental modification to reduce high-impact forces

Prompt evaluation of acute paraplegia improves overall outcome potential.

Common Misconceptions

“If Surgery Is Done, Myelomalacia Cannot Happen”

Surgery reduces compression but cannot always prevent secondary necrosis.

“If the Dog Is Stable After Surgery, Risk Is Gone”

Progression may occur days after intervention.

“All Deep Pain-Negative Dogs Will Develop Myelomalacia”

While risk increases, most deep pain-negative dogs do not develop progressive necrosis.

The Emotional Impact on Owners

Myelomalacia is particularly distressing because:

• Initial surgery may seem successful

• Deterioration may occur unexpectedly

• Progression can be rapid

Veterinary teams must balance medical clarity with compassionate communication.

Final Considerations: A Severe but Uncommon Outcome

Myelomalacia represents one of the most severe complications of IVDD in Dachshunds. While uncommon relative to overall IVDD prevalence, it disproportionately affects those with the most severe spinal cord injuries.

Its development reflects not just compression, but catastrophic disruption of spinal cord perfusion and cellular integrity.

Understanding early signs, maintaining vigilant neurological monitoring, and communicating transparently about prognosis are central to responsible clinical care in this breed.

For Dachshunds with severe IVDD, awareness of myelomalacia is not intended to create fear—but to support informed, medically grounded decision-making.

Sources & Further Reading

• American College of Veterinary Surgeons (ACVS). Intervertebral Disc Disease in Dogs.

• American College of Veterinary Internal Medicine (ACVIM). Consensus Statements on Canine Spinal Cord Injury.

• Brisson, B.A. (2010). Intervertebral Disc Disease in Dogs. Vet Clin North Am Small Anim Pract.

• Olby, N.J., Levine, J.M., et al. Research on spinal cord injury and recovery in dogs.

• Sharp, N.J.H., Wheeler, S.J. Small Animal Spinal Disorders: Diagnosis and Surgery. Elsevier.

• Cornell University College of Veterinary Medicine – Neurology Resources.

• UC Davis School of Veterinary Medicine – Veterinary Neurosurgery.