Intervertebral disk disease in Cats (Felis) | Vetlexicon
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Intervertebral disk disease

ISSN 2398-2950


Introduction

  • Cause: extrusion or protrusion of disk material into vertebral canal.
  • Signs: uncommon compared with dog.
  • Diagnosis: radiography, myelography, advanced imaging (MRI or CT).
  • Treatment: conservative or decompressive surgery if severe or progressive clinical signs.
  • Prognosis: good if only minor neurological deficits or if early surgery in severe cases.
    Print off the owner factsheet Intervertebral disk herniation or "slipped disk"   Intervertebral disk herniation or slipped disk  to give to your client.

Presenting signs

  • Neck or back pain.
  • Paraparesis or tetraparesis depending on location of herniated disk in the spinal cord.
  • Abnormal gait.
  • Reluctance to jump.
  • Flaccid tail.
  • Urinary or fecal incontinence.

Acute presentation

  • Paraparesis
  • Tetraparesis.
  • Severe neck or back pain.

Age predisposition

  • Mean age at onset 8 years.
  • Range reported: 18 months to 17 years.
  • Post-mortem studies have shown Hansen type II intervertebral disk herniation to be a common incidental age-related change in older cats.

Breed/Species predisposition

  • No known breed predisposition.
  • Pure breeds may be over-represented (but total number of cases is too small) to draw definite conclusions.

Pathogenesis

Pathophysiology

  • Thoracic and lumbar disk protrusion most common clinically, cervical disk protrusion most prevalent in post-mortem studies.
  • Both acute intervertebral disk extrusion and chronic intervertebral disk protrusion are reported to occur in cats.
  • Cervical spinal region has been reported as the most common site for disk protrusion (Hansen type II) followed by the mid to caudal lumbar region.
  • Disk extrusions (Hansen type I) occur most commonly in the thoracolumbar region with a predilection to the caudal lumbar and lumbrosacral regions. The more frequently reported sites were between the T11/T12 and L1/L2 disk spaces and at the L4/L5 disk interspace.
  • Cats have tendencies to jump while applying increased biomechanical loads on their lumbar spine, which may predispose for caudal lumbar disk extrusions.

Type I disk protrusion

  • Calcification of vertebral disk   →   sudden extrusion of disk material into vertebral canal   →   pain and neurological deficits.

Type II disk protrusion

  • Degenerative changes in intervertebral disk   →   slow protrusion of material into intervertebral space   →   spinal cord compression   →   slowly progressive neurological signs.
  • Fibroid disk degeneration is the most common form.

Timecourse

  • May be acute or chronic in nature.

Diagnosis

Presenting problems

  • Spinal pain.
  • Neurological deficits.
  • Reluctance to jump.
  • Flaccid tail.
  • Urinary and/or fecal incontinence.

Client history

  • Progressive ataxia, tetraparesis or paraparesis.
  • Abnormal gait.
  • Spinal pain.
  • Flaccid tail.
  • Urinary and/or fecal incontinence.

Clinical signs

  • Spinal pain.
  • Neurological deficits (sensory or motor).
  • Paraparesis or tetraparesis.
  • Muscle atrophy caudal to lesion.

Diagnostic investigation

Radiography

  • Plain spinal radiographs Radiography: spine should be taken before myelography although rarely show lesion.
  • Narrowing of disk space, end plate sclerosis and osteophyte production.
  • Calcified disk material in intervertebral space or within vertebral canal (Type I).

Contrast radiography

  • Myelography Radiography: myelography is required to demonstrate site of spinal cord compression Spine: cervical cord compression - myelogram .
  • Also helps to rule out differential diagnoses such as neoplasia.
  • Extradural spinal cord compression on lateral or DV view  Spine: extradural compression - myelogram lateral   Spine: extradural compression - myelogram VD .

Cytopathology

Advanced imaging

  • Computed tomography (CT Computed tomography (CT)) might reveal a hyperattenuating compressive lesion, especially in cases where the intervertebral disk is mineralized.
  • MRI Magnetic resonance imaging: spineprovides better contrast resolution than CT or myelography. Considered as 'gold standard' for imaging intervertebral disks.
  • MRI usually reveals extradural material compressing the spinal cord above the affected disk space.
  • Intramedullary migration of the intervertebral disk and focal intramedullary edema associated with extrusion of a small volume of intervertebral material have also been reported in cats.

Confirmation of diagnosis

Discriminatory diagnostic features

  • Signs.
  • Cytopathology.

Definitive diagnostic features

  • Radiography.
  • Advanced imaging (CT or MRI).
  • Visualization at surgery.

Gross autopsy findings

  • Intervertebral disk protrusion may be seen at PM with no clinical significance.

Histopathology findings

  • Fibroid disk degeneration.

Differential diagnosis

Treatment

Initial symptomatic treatment

  • Manage urinary incontinence - manual bladder drainage if required and antibiotics for urinary tract infection Urinary incontinence.
  • Regular turning/physiotherapy if paralyzed to prevent development of decubital ulcers.

Standard treatment

Non-surgical

  • Box rest for 2-3 weeks at least.
  • Continually assess neurological status Neurological examination  - surgical intervention may be required if condition deteriorating.
  • Analgesia Analgesia: overview if acutely painful, eg NSAID Analgesia: NSAID or opioid  Analgesia: opioid.
    Do not use combination of NSAIDs and glucocorticoids.
  • In per acute cases, methylprednisolone Methylprednisolone may reduce cord swelling and damage.
  • Overall cats do not seem to respond as well to conservative treatments due to difficulty in restraining them.

Surgical

  • Hemilaminectomy for thoracolumbar disease.
  • Dorsal laminectomy for lumbrosacral disk disease.
  • Ventral slot for cervical disk disease.
  • Muscle massage and passive physiotherapy useful to speed recovery.

Prevention

Outcomes

Prognosis

  • Good if minor neurological deficits.

Expected response to treatment

  • Neurological signs should stop progressing - additional treatment indicated if progression.

Reasons for treatment failure

  • Severe spinal trauma at time of prolapse or delayed surgical intervention.
  • Development of myelomalacia.

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Marioni-Henry K (2010) Feline spinal cord diseases. Vet Clin North Am Small Anim Pract 40 (5), 1011-1028 PubMed.
  • Harris J E, Dhupa S (2008) Lumbrosacral intervertebral disc disease in six cats. JAAHA 44 (3), 109-115 PubMed.
  • Maritato K C, Colon J A, Mauterer J V (2007) Acute non-ambulatory tetraparesis attributable to cranial cervical intervertebral disk disease in a cat. J Feline Med Surg (6), 494-498 PubMed
  • Marioni-Henry K, Vite C H, Newton A L et al (2004) Prevalence of diseases of the spinal cord in cats. JVIM 18 (6), 851-858 PubMed.
  • McConnell J F, Garosi L S (2004) Intramedullary intervertebral disc extrusion in a cat.Vet Radiol Ultrasound 45 (4), 327-330 PubMed.
  • Lu D, Lamb C R, Wesselingh K et al (2002) Acute intervertebral disc extrusion in a cat: clinical and MRI findingsJ Feline Med Surg (1), 65-68 PubMed.
  • Knipe M F, Vernau K M, Hornof W J et al (2001) Intervertebral disk extrusion in six cats. JFMS (3), 161-168 PubMed.
  • Muñana K R, Olby N J, Sharp N J et al (2001) Intervertebral disk disease in 10 cats. JAAHA 37 (4), 384-389 PubMed.
  • Kathmann I, Cizinauskas S, Rytz U et al (2000) Spontaneous lumbar intervertebral disk protrusion in cats - literature review and case presentations. JFMS (4), 207-212 PubMed.
  • Bagley R S, Tucker R L, Moore M P et al (1995) Radiographic diagnosis. Intervertebral disk extrusion in a cat. Vet Radiol 36 (5), 380-382 VetMedResource.
  • Braund K G, Shores A & Brawner W R (1990) Recovering from spinal trauma - the rehabilitation steps, complications and prognosis. Vet Med 85, 740-743.
  • Sparkes A H & Skerry T M (1990) Successful management of a prolapsed intervertebral disk in a Siamese cat. Feline Pract 18 (1), 7-9 VetMedResource.
  • Salisbury S K & Cook J R (1988) Recovery of neurologic function following focal myelomalacia in a cat. JAAHA 24 (2), 227-230 AGRIS FAO.