Issues

Panosteitis

DEFINITION

A self-limiting, painful condition affecting one or more of the long bones of young, medium- to large-breed dogs that is characterized clinically by lameness and radiographically by high density of the marrow cavity.

 

PATHOPHYSIOLOGY

Cause unknown.

Attempts to isolate microorganisms have failed.

Metabolic, allergic, or endocrine aberrations—without support.

Pain—may owe to the disturbance of endosteal and periosteal elements, vascular congestion, or high intramedullary pressure.

 

SYSTEMS AFFECTED

Musculoskeletal—lameness of variable intensity; may affect a single limb or become a shifting leg lameness.

 

GENETICS

No proven transmission.

Predominance of German shepherds in the affected population strongly suggests an inheritable basis.

 

INCIDENCE/PREVALENCE

No reliable estimates; common

 

SIGNALMENT

Species

Dog

 

Breed Predilections

German shepherds and German shepherd mixes—most commonly affected.

Medium to large breeds—most commonly affected.

 

Mean Age and Range

Usually 5–18 months of age

As young as 2 months and as old as 5 years

 

Predominant Sex

Male

 

SIGNS

General Comments

Lameness—if no distinct abnormalities noted on physical examination or radiographs, repeat examinations 4–6 weeks later.

 

Historical Findings

No associated trauma.

Lameness—varying intensity; usually involves the forelimbs initially; may affect the hind limbs; may see shifting leg lameness; may be non-weight-bearing.

Severe disease—mild depression; inappetence; weight loss.

 

Physical Examination Findings

Pain—on deep palpation of the long bones (diaphysis) in an affected limb; distinguishing characteristic; palpate firmly along the entire shaft of each bone while carefully avoiding any pinching of nearby muscle.

Bones—ulna most commonly affected; may affect radius, humerus, femur, and tibia (in decreasing order of frequency) either concurrently or subsequently.

May note low-grade fever.

May see muscle atrophy.

 

CAUSES

Unknown

 

RISK FACTORS

Purebred German shepherd or German shepherd mix

 

DIAGNOSIS

DIFFERENTIAL DIAGNOSIS

Always consider the diagnosis with lameness in a young German shepherd or German shepherd mix.

May occur alone or with other juvenile orthopedic diseases.

Osteochondritis dissecans.

Fragmented medial coronoid process.

Un-united anconeal process.

Hip dysplasia.

Fractures and ligamentous injuries from unobserved trauma.

Shifting leg lameness—immune-mediated arthritides; Lyme disease; bacterial endocarditis.

Coccidioidomycosis.

Bacterial osteomyelitis.

Hypertrophic osteodystrophy.

 

CBC/BIOCHEMISTRY/URINALYSIS

Usually normal

May note eosinophilia early in disease

 

OTHER LABORATORY TESTS

N/A

 

IMAGING

Radiographic densities within the medulla of long bones—characteristic; confirm diagnosis.

Early, middle, and late radiographic lesions.

Early—trabecular pattern of the ends of the diaphysis becomes more prominent; may appear blurred; may see granular opacities.

Middle—patchy sclerotic opacities first around the nutrient foramen and later throughout the diaphysis; widened cortex; thickened periosteum with increased opacity.

Late—during resolution, diminished overall opacity of the medullary canal (toward normal); a coarse trabecular pattern and some granular opacity may remain; may be a period in which the medullary canal becomes more lucent than normal.

Bone scintigraphy may reveal subtle lesions that later become more apparent on follow-up radiographs.

 

DIAGNOSTIC PROCEDURES

Bone biopsy—occasionally indicated to rule out neoplasia and bacterial or fungal osteomyelitis that have similar radiographic appearances.

 

PATHOLOGIC FINDINGS

Biopsy or necropsy—rarely performed because of excellent prognosis for recovery.

No gross pathologic lesions.

Degeneration of the marrow adipocytes surrounding the nutrient foramen followed by proliferation of vascular stromal cells within the marrow sinusoids.

Osteoid formation and endosteal new bone formation—progress proximally and distally.

Vascular congestion—may accompany the proliferation of new bone, secondarily stimulating endosteal and periosteal reaction.

Remodeling of the endosteum—occurs during resolution; reestablishes normal endosteal and marrow architecture.

 

TREATMENT

APPROPRIATE HEALTH CARE

Outpatient

 

NURSING CARE

Maintenance and replacement fluid therapy—occasionally owing to prolonged periods of inappetence and pyrexia.

 

ACTIVITY

Limited—not shown to hasten recovery; lessens pain.

Moderate to severe disease—pain may cause self-limited movement leading to muscle atrophy.

 

CLIENT EDUCATION

Warn client that patient may develop other juvenile orthopedic diseases.

Inform client that signs of pain and lameness may last for several weeks.

Warn client that recurrence of clinical signs is common up to 2 years of age.

 

SURGICAL CONSIDERATIONS

N/A

 

PATIENT MONITORING

Recheck lameness every 2–4 weeks to detect more serious concurrent orthopedic problems.

 

PREVENTION/AVOIDANCE

N/A

 

AGE-RELATED FACTORS

Typically affects immature and young dogs

 

ZOONOTIC POTENTIAL

N/A

 

PREGNANCY/FERTILITY/BREEDING

Females reported to be more susceptible to panosteitis during estrus; no proven relationship to reproductive hormones or pregnancy.

 

SYNONYMS

Enostosis

Eosinophilic panosteitis

Fibrous osteodystrophy

Juvenile osteomyelitis

 

ABBREVIATION

NSAID = nonsteroidal anti-inflammatory drug

 

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

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