Group 10 Š Osteomyleitis in skeletally mature small animal with hematogenous spread



1. Acute - Signs to expect from a small animal with hematogenous osteomyelitis would 
include heat pain and swelling associated with lameness.  Anorexia starting 5-21 days 
after the onset.  On the CBC you will see a leukocytosis with a degenerative left shift.  
There will be soft tissue changes and bony lysis.  Positive cultures from the bone but 
blood cultures are frequently unrewarding because bacteremia is intermittent.  
Chronic Š Intermittent lameness with draining tracts, atrophy induration, local pain, 
fluctuant swellings, periodic febrile episodes and inappetence.  Bone proliferation, 
bone destruction, sclerotic densities.  Radiographs will reveal a sequestrum.  

2. Local and systemic treatment is necessary.  Take aerobic and anaerobic cultures 
before starting antibiotic therapy.  Perform a sensitivity test for selecting the 
appropriate antibiotic.  Staph aureus is usually the bacteria involved.  Cephazolin will 
be one of the drugs of choice given 15-20 mg/kg IV TID.  After 24 hours the 
antibiotics can be given orally.  During long term treatments the drug choices should 
change to avoid resistance.  Therapy should continue for 6 weeks for appropriate 
treatment.  Take a second culture after 6 weeks and repeat radiographs for 
reevaluation.  If the culture is still posititve change the antibiotic and explore the site 
to remove source of the infection.  Initial therapy is frequently circumvented because 
of economic and aesthetic considerations.  The resultant problem is harder to fix than 
the initial problem.  
3. Prognosis for acute disease is fair to good with treatment and as long as there are no 
bone fragments.  Chronic is guarded until dead bone is removed and then the 
prognosis is fair.  
4. Differences in our case compared with others include older animals will have 
draining tracts which arenÕt usually seen in younger animals.  Large animals are more 
prone to wounds as sources of infection.  Neonates are more likely to have 
hematogenous spread as compared to adults.  Prognosis is better with small animals 
versus large animals because larger animals are more affected by loss of function or 
limb, etc.  In large animal neonates hematogenous bacteria often colonizes in the 
growth plates of bones.  
In our case being a small animal that is skeletally mature the osteomyelitis is more likely 
a chronic infection.  These older animals will mount a better immune response, the source 
of infection is more likely due to a systemic infection instead of a wound.