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What is Bone Sequestrum?

In regards to bone sequestra, the body will try to resorb the dead bone fragments naturally but in many cases, it cannot and the condition requires veterinary intervention.  A bone sequestrum will often develop after injury to the area and begin with symptoms of pain and lameness. It can often be diagnosed with radiographs and treated with surgical removal.  It not removed, healing can be delayed, leading to infection and prolonged recovery.  If treated properly, prognosis of a full recovery is good.

 

A bone sequestrum in a horse is a piece of dead bone that has detached from the healthy bone.  If you suspect your horse is experiencing some discomfort or abnormalities, you should have him examined by your veterinarian.

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Symptoms of Bone Sequestrum in Horses

Symptoms may include:

  • Pain
  • Lameness
  • Inflammation at the site of sequestrum
  • Heat at the site of sequestrum
  • Open wound with or without draining

Types

Bone sequestra can develop in any age of a horse.  They are more likely to develop in young horses than mature horses.  With an injury, the trauma leads to compromised blood supply to the outer cortex of the bone as well as disrupting the periosteum.  This causes the outer cortex to undergo devascularization and separate from the outer bone.

Causes of Bone Sequestrum in Horses

Bone sequestrum is a piece of a dead bone that has separated from the healthy, sound bone during necrosis.  If the part of the bone that is separated cannot be revascularized, the granulation tissue often sequesters it; this is the body’s attempt to extrude the dead bone.  A bone sequestrum can delay the healing process due to being a possible point of inflammation and infection.  These can develop after injury or trauma. In some cases of an infected wound with a bone sequestrum, it will not heal until the sequestrum is removed; it will continue to drain since it will not be able to heal.

Diagnosis of Bone Sequestrum in Horses

A radiograph will show the sequestrum as a sclerotic segment of bone with a radiolucent zone surrounding it.  It is recommended the image be taken 10 to 14 days after initial injury to see if there is a bone sequestrum developing or not.  If the image is taken within 7 days of initial injury, a sequestrum cannot be detected radiographically.  

Some veterinarians may want to use ultrasonography as another form of imaging.  Some more specialized clinics may even suggest an MRI or CT scan to get another view at the affected area.  These machines are at more specialized facilities so you may need to visit one of them if recommended.

Your veterinarian may want to perform blood work in order to check for other issues your horse may be experiencing.  A complete blood count (CBC) and chemistry panel will be recommended in order to check general organ function.  Blood work is also important before any type of surgery involving your horse going under anesthesia to check liver and kidney function.  This will check for abnormalities and prevent unnecessary complications from surgery.

Treatment of Bone Sequestrum in Horses

Treatment of this condition typically consists of surgery to debride the affected area and remove the necrotic bone.  Also, antibiotics should be prescribed to treat and prevent infection.  Debridement of the wound should also be done.  If you try just medications alone, it can take a long time for the bone sequestrum to be absorbed.  There are a variety of antibiotics your veterinarian may prescribe for his condition and it may take an extended course to get the infection under control.  Pain medications may also be suggested depending on your horse’s sensitivity to his condition.  

If the bone sequestrum is a secondary condition to another issue, it may not heal until the dead layer of bone is completely removed.  While small bone sequestra may spontaneously resorb, larger ones typically require surgical intervention.  This will require your horse to undergo anesthesia for the procedure.  

Additional treatments and therapies may be administered in accordance with your horse’s condition.  Stall rest may be suggested or he may just need to be off pasture during his treatment process.  Each horse has his own treatment plan in response to where the sequestra are located.

Recovery of Bone Sequestrum in Horses

If the sequestrum resorbs on its own, you should not need to do anything but monitor it.  However, if it remains, your veterinarian will need to intervene with treatment.  With surgical removal of the bone sequestrum, most horses recover well.  If the sequestrum is not removed, the delayed healing process can lead to more complicated secondary issues.  It treated properly, his prognosis of recovery is good.