Page 460 - The Veterinary Care of the Horse

sudden worsening of lameness following fracture repair; this can occur any time between
•
1 and 4 weeks after surgery.
VetBooks.ir DIAGNOSIS

Diagnosis is made on the clinical signs and imaging techniques.

Radiographic changes include:
• loss of bone density

• new bone formation

• the presence of a sequestrum (see page 295)

Unfortunately the very early signs of osteomyelitis cannot be seen on radiographs. The

changes caused by infection are not visible until 50–70% of the bone has been demineralized
and this may take up to 21 days.

Scintigraphy using labelled white blood cells which collect at sites of infection is very
useful, but not widely available.

Ultrasound can be useful in detecting small pockets of pus building up around surgical

implants such as bone plates and screws. With ultrasound guidance these can be aspirated
and cultured to determine which bacteria are present and their antibiotic sensitivity.

TREATMENT
The treatment depends on the cause of the infection and how well established it is. It is likely

to include the following.

• Surgery to remove any dead or grossly infected soft tissue or bone.
• Culture of the bacteria to determine their antibiotic sensitivity.

• Removal of any infected implants such as bone plates and screws.

• Bone grafts may be useful to promote healing of infected fractures.

• Administration of broad spectrum antibiotics for a minimum of 3 weeks. These are
usually injected for 7–10 days and followed up with oral antibiotics.

• Antibiotic-impregnated beads may be placed at the wound site. This technique gives high

antibiotic concentrations at the site of infection.
• Antibiotics may be infused directly into the medullary cavity.

• Antibiotics can be delivered to the wound site by regional intravenous infusion. A

tourniquet is applied to the limb above the area of infection. The diluted antibiotic is then
injected into a superficial vein under pressure. Antibiotics delivered in this way or by