Issues

Discospondylitis

 

Discospondylitis Is 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

 

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 is 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

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

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.

 

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

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 organisms 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 is common.

 

ZOONOTIC POTENTIAL

Brucella canis—human infection uncommon but may occur

 

SYNONYMS

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

ABBREVIATIONS

CSF = cerebrospinal fluid

NSAID = nonsteroidal anti-inflammatory drug

 

Visit your veterinarian as early recognition, diagnosis, and treatment are essential.

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