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Basics ⬇

Basics

Definition

A bacterial or fungal infection of the intervertebral discs and adjacent vertebral bodies.

Pathophysiology

  • Hematogenous spread of bacterial or fungal organisms-most common cause.
  • Neurologic dysfunction-may occur; usually the result of spinal cord compression caused by proliferation of bone and fibrous tissue; less commonly owing to luxation or pathologic fracture of the spine, epidural abscess, or extension of infection to the meninges and spinal cord.

Systems Affected

  • Musculoskeletal-infection and inflammation of the spine
  • Nervous-compression of the spinal cord

Genetics

  • No definite predisposition identified.
  • An inherited immunodeficiency has been detected in a few cases.

Incidence/Prevalence

Approximately 0.1–0.8% of dog hospital admissions

Geographic Distribution

  • More common in the southeastern United States.
  • Grass awn migration and coccidiomycosis-more common in certain regions.

Signalment

Species

Dog; rare in cat

Breed Predilections

Large and giant breeds, especially German shepherd and Great Dane.

Mean Age and Range

  • Mean age-4–5 years
  • Range-5 months–12 years

Predominant Sex

Males outnumber females by ∼2:1

Signs

Historical Findings

  • Onset usually relatively acute; some patients have mild signs for several months before examination.
  • Pain-difficulty rising, reluctance to jump, and stilted gait are most common signs.
  • Ataxia or paresis.
  • Weight loss and anorexia.
  • Lameness.
  • Draining tracts.

Physical Examination Findings

  • Focal or multifocal areas of spinal pain in >80% of patients.
  • Any disc space may be affected; lumbosacral space is most commonly involved.
  • Paresis or paralysis, especially in chronic, untreated cases.
  • Fever in ∼30% of patients.
  • Lameness.

Causes

  • Bacterial-Staphylococcus pseudintermedius is the most common. Others include Streptococcus, Brucella canis, and E. coli, but virtually any bacteria can be causative.
  • Fungal-Aspergillus, Paecilomyces, Scedosporium apiospermum, and Coccidioides immitis.
  • Grass awn migration is often associated with mixed infections, especially Actinomyces; tends to affect the L2–L4 disc spaces and vertebrae.
  • Other causes-surgery, bite wounds.

Risk Factors

  • Urinary tract infection; reproductive tract infection
  • Periodontal disease
  • Bacterial endocarditis
  • Pyoderma
  • Immunodeficiency

Diagnosis ⬆ ⬇

Diagnosis

Differential Diagnosis

  • Intervertebral disc protrusion-may cause similar clinical signs; differentiated on the basis of radiography and myelography.
  • Vertebral fracture or luxation-detected on radiographs.
  • Vertebral neoplasia-usually does not affect adjacent vertebral end plates.
  • Spondylosis deformans-rarely causes clinical signs; has similar radiographic features, including sclerosis, ventral spur formation, and collapse of the disc space; rarely causes lysis of the vertebral end plates.
  • Focal meningomyelitis-often identified by CSF analysis.

CBC/Biochemistry/Urinalysis

  • Hemogram-often normal; may see leukocytosis.
  • Urinalysis-may reveal pyuria and/or bacteriuria with concurrent urinary tract infections.

Other Laboratory Tests

  • Aerobic, anaerobic, and fungal blood cultures identify the causative organism in about 35% of cases; obtain if available.
  • Sensitivity testing-indicated if cultures are positive.
  • Urine cultures-indicated; positive in about 30% of patients.
  • Organisms other than Staphylococcus spp.-may not be the cause.
  • Serologic testing for Brucella canis-indicated.

Imaging

  • Spinal radiography-usually reveals lysis of vertebral end plates adjacent to the affected disc, collapse of the disc space, and varying degrees of sclerosis of the end plates and ventral spur formation; may not see lesions until 3–4 weeks after infection.
  • Myelography-indicated with substantial neurologic deficits; determine location and degree of spinal cord compression, especially if considering decompressive surgery; spinal cord compression caused by discospondylitis typically displays an extradural pattern.
  • Computed tomography or magnetic resonance imaging-more sensitive than radiography; indicated when radiographs are normal or inconclusive.

Diagnostic Procedures

  • CSF analysis-occasionally indicated to rule out meningomyelitis; usually normal or reveals mildly high protein.
  • Bone scintigraphy-occasionally useful for detecting early lesions; helps clarify if radiographic changes are infectious or degenerative (spondylosis deformans).
  • Fluoroscopically guided fine-needle aspiration of the disc-valuable for obtaining tissue for culture when blood and urine cultures are negative and there is no improvement with empiric antibiotic therapy.

Pathologic Findings

  • Gross-loss of normal disc space; bony proliferation of adjacent vertebrae.
  • Microscopic-fibrosing pyogranulomatous destruction of the disc and vertebral bodies.

Treatment ⬆ ⬇

Treatment

Appropriate Health Care

  • Outpatient-mild pain managed with medication.
  • Inpatient-severe pain or progressive neurologic deficits require intensive care and monitoring.

Nursing Care

Non-ambulatory patients-keep on a clean, dry, well-padded surface to prevent decubital ulceration.

Activity

Restricted

Diet

Normal

Client Education

  • Explain that observation of response to treatment is very important in determining the need for further diagnostic or therapeutic procedures.
  • Instruct the client to immediately contact the veterinarian if clinical signs progress or recur or if neurologic deficits develop.

Surgical Considerations

  • Curettage of a single affected disc space-occasionally necessary for patients that are refractory to antibiotic therapy.
  • Goals-remove infected tissue; obtain tissue for culture and histologic evaluation.
  • Decompression of the spinal cord by hemilaminectomy or dorsal laminectomy-indicated for substantial neurologic deficits and spinal cord compression evident on myelography when there is no improvement with antibiotic therapy; also perform curettage of the infected disc space; it may be necessary to perform surgical stabilization if more than one articular facet is removed.

Medications ⬆ ⬇

Medications

Drug(s) Of Choice

Antibiotics

  • Selection based on results of blood cultures and serology.
  • Negative culture and serology-assume causative organism is Staphylococcus spp.; treat with a cephalosporin (e.g., cefadroxil; dogs, 22 mg/kg PO q12h; cats, 22 mg/kg PO q24h) for 8–12 weeks.
  • Acutely progressive signs or substantial neurologic deficits-initially treated with parenteral antibiotics (e.g., cefazolin; dogs and cats, 20–35 mg/kg IVq8h).
  • Brucellosis-treated with tetracycline (dogs, 15 mg/kg PO q8h) and streptomycin (dogs, 3.4 mg/kg IM q24h) or enrofloxacin (dogs, 2.5–5 mg/kg PO q12h).

Analgesics

  • Signs of severe pain-treated with an analgesic (e.g., oxymorphone; dogs, 0.05–0.2 mg/kg IV, IM, SC q4–6h).
  • Taper dosage after 3–5 days to gauge effectiveness of antibiotic therapy.

Contraindications

Glucocorticoids

Precautions

Use NSAIDs and other analgesics cautiously-may cause a temporary resolution of clinical signs even when infection is progressing; when used, discontinue after 3–5 days to assess efficacy of antibiotic therapy.

Possible Interactions

None

Alternative Drug(s)

  • Initial therapy-cephradine (dogs, 20 mg/kg PO q8h); cloxacillin (dogs, 10 mg/kg PO q8h).
  • Refractory patients-clindamycin (dogs and cats, 10 mg/kg PO q12h), enrofloxacin (dogs, 5–20 mg/kg PO q24h; cats, 5 mg/kg PO q24h), orbifloxacin (dogs and cats, 2.5–7.5 mg/kg PO q24h).

Follow-Up ⬆ ⬇

Follow-Up

Patient Monitoring

  • Reevaluate after 5 days of therapy.
  • No improvement in pain, fever, or appetite-reassess therapy; consider a different antibiotic, percutaneous aspiration of the affected disc space, or surgery.
  • Improvement-evaluate clinically and radiographically every 4 weeks.

Prevention/Avoidance

Early identification of predisposing causes and prompt diagnosis and treatment-help reduce progression of clinical symptoms and neurologic deterioration.

Possible Complications

  • Spinal cord compression owing to proliferative bony and fibrous tissue.
  • Vertebral fracture or luxation.
  • Meningitis or meningomyelitis.
  • Epidural abscess.

Expected Course and Prognosis

  • Recurrence is common if antibiotic therapy is stopped prematurely (before 8–12 weeks of treatment).
  • Some patients require prolonged therapy (1 year or more).
  • Prognosis-depends on causative organism and degree of spinal cord damage.
  • Mild or no neurologic dysfunction (dogs)-usually respond within 5 days of starting antibiotic therapy.
  • Substantial paresis or paralysis (dogs)-prognosis guarded; may note gradual resolution of neurologic dysfunction after several weeks of therapy; treatment warranted.
  • Brucella canis-signs usually resolve with therapy; infection may not be eradicated; recurrence common.

Miscellaneous ⬆

Miscellaneous

Associated Conditions

See “Risk Factors”

Age-Related Factors

N/A

Zoonotic Potential

Brucella canis-human infection uncommon but may occur

Pregnancy/Fertility/Breeding

N/A

Synonyms

  • Diskitis
  • Intervertebral disc infection
  • Intradiskal osteomyelitis
  • Vertebral osteomyelitis

See Also

Brucellosis

Abbreviations

  • CSF = cerebrospinal fluid
  • NSAID = nonsteroidal anti-inflammatory drug

Suggested Reading

Ameel L, Martlè V, et al. Discospondylitis in the dog: A retrospective study of 18 cases. Vlaams Diergeneeskundig Tijdschrift 2009, 78(5):347–353.

Bagley RS. Diskospondylitis. Fundam Clin Neuro 2005, 172–173(283–285):346.

Braund KG, Sharp NJH. Discospondylitis. In: Clinical Neurology in Small Animals: Localisation, diagnosis and Treatment. Ithaca, NY: IVIS, 2003.

Burkert BA, Kerwin SC, Hosgood GL, Pechman RD, Ponti Fontenelle J. Signalment and clinical features of diskospondylitis in dogs: 513 cases (1980–2001). J Am Vet Med Assoc 2005, 227(2):268–275.

Fischer A, Mahaffey MB, Oliver JE. Fluoroscopically guided percutaneous disk aspiration in 10 dogs with diskospondylitis. J Vet Intern Med 1997, 11:284–287.

Johnson RG, Prata RG. Intradiskal osteomyelitis: A conservative approach. JAAHA 1983, 19:743–750.

Kerwin SC, Lewis DD, Hribernik TN, et al. Diskospondylitis associated with Brucella canis infection in dogs: 14 cases (1989–1991). J Am Vet Med Assoc 1992, 201:1253–1257.

Kornegay JN. Diskospondylitis. In: Kirk RW, ed., Current Veterinary Therapy IX. Philadelphia: Saunders, 1986, pp. 810–814.

Thomas WB. Diskospondylitis and other vertebral infections. Vet Clin North Am Small Anim Pract 2000, 30:169–182.

Author Mathieu M. Glassman

Consulting Editor Walter C. Renberg

Acknowledgment The author and editors acknowledge the prior contribution of Peter K. Shires.

Client Education Handout Available Online