Veterinary Neurology Case Study

Study of 15 Dogs with Intervertebral Disc Disease

• 15 dogs met the inclusion criteria from three veterinary hospitals: Auna Especialidades Veterinarias (9), Anicura Glòries Hospital Veterinari (5), and Hospital Veterinario UCV (1).

Characteristics of the Dogs

• Enrolled breeds, body weight, gender, age, onset of clinical signs, neurological grade at diagnosis, neurolocalization, presence of cervical hyperesthesia, and other relevant information are listed in Table 1.

Myelography and Myelo-CT Findings

• No complications associated with myelography were observed in the included dogs.
• Myelo-CT findings showed a focal extradural bilobed "seagull"-shaped compressive lesion dorsal to the annulus fibrosus in 87% of cases (13/15).
• A focal thinning of the ventral contrast column in sagittal reconstruction and transverse plane was seen in all cases.
• Extruded material was hypoattenuating in the soft tissue algorithm with HU ranging from 22 to 118.

Characteristics of Extruded Material

• The median relative length percentage of compression was 63% (range: 35–93%).
• The median relative height percentage of compression was 40% (range: 34–58%).
• Appearance of extruded material varied, including:
  • Liquid opaque with small white spots (3 cases)
  • Whitish liquid (8 cases)
  • Gelatinous whitish (2 cases)
  • Gelatinous pinkish (2 cases)

Compressive Hydrated Nucleus Pulposus Extrusion (HNPE)

• HNPE is a type of intervertebral disc herniation in dogs characterized by sudden extrusion of hydrated, non-degenerated, or minimally-degenerated nucleus pulposus material.
• This leads to contusion and a variable degree of spinal cord compression.
• HNPE was previously referred to as intraspinal discal cyst.

Diagnostic Imaging

• Magnetic Resonance Imaging (MRI) is the diagnostic modality of choice for HNPE.
• MRI shows extradural, typically "seagull"-shaped, compressive material of hydrated signal intensity immediately dorsal to the affected disc space.

Alternative Diagnostic Modality

• Myelo-CT (Computed Tomography) may be used as an alternative diagnostic modality when MRI is not available.
• The myelo-CT characteristics of HNPE have not been previously published.

Treatment and Prognosis

• Conservative treatment of HNPE has been associated with a good prognosis, even with severe neurological deficits.

Case Series

• This retrospective case series aims to describe the myelo-CT findings in 15 dogs with gross surgical findings consistent with cervical compressive HNPE.