Case of the Week: Osteomyelitis

Sheba is a 3 year old female German Shepherd.  When she was 7 months old she was attack by another dog and suffered from severe bite wounds to her left front leg.  Her parents took her to a veterinarian where she received treatment for her bite wounds.  Several months later she developed draining tract wounds in the area of the bites.  Multiple antibiotics had been administered over the last 3 years without resolution of the draining wound.


On presentation to our hospital, we found Sheba to be bright and alert with no abnormalities on physical examination with the exception of her left front leg.  She was toe touching lame.  Sheba's leg was swollen at the end of her humerus, just before the bend of her elbow, tender to touch and had two draining tract wounds within the swollen area.  Keep in mind this was an injury that was a little over 2 years old.


Radiographs were taken (left).  In doctor terms, there is bone lysis and sclerosis with loss of cortical bone and bone sequestra.  In other words, loss of bone along the margins of the bone and reactive bone with a piece of the original bone separated from it's origin.  


These findings in addition to the draining tracts and soft tissue swelling makes our diagnosis Osteomyelitis.  


Osteomyelitis is an infection the bone. Infection of the bone, called osteomyelitis can be acute or chronic. Acute infection show up quickly, while those that are chronic spread slowly and symptoms can take months to develop.  In Sheba's case, chronic.


The most common causes of bone infection in both people and dogs are staphylococcal bacteria, followed by streptococcal bacteria, and, more rarely, other bacterial and fungal organisms. Bone infections can arise from infections in other areas of the body carried to the bone by the bloodstream.


The more common causes of the bone infections in dogs are from outside of the body via bite wounds, other puncture wounds, compound fractures, and bone surgeries. Severe dental disease can lead to infection of the bones of the jaws.


Osteomyelitis can also be acquired secondarily to other brain injuries, most commonly brain infections, traumas, brain tumors and poisonings.


The initial signs are pain, swelling, fever, and if a limb is involved, lameness. These signs are usually accompanied by depression and loss of appetite. In time the infection usually breaks through the skin, and a blood-tinged or pus discharge occurs.


Diagnosis is made by the history, clinical signs, confirmed by blood tests and x-rays. It is advisable to have the discharge cultured in order to identify the organisms that are causing the infection and also to run a sensitivity test to determine which antibiotic will be effective in treatment. Although these tests are extra cost, bone infections can be difficult to clear up and a hit-or-miss use of antibiotics can make the condition worse.


In most cases it will be necessary to drain the wound surgically and remove all dead and infected tissues from the bone. Vigorous and often long-term antibiotic treatment will be essential, both systematically (by injection or mouth) and locally (into the wound). The wound will either be left open or closed with a tube inserted for drainage. Although most bone infections clear up with adequate treatment, some do not respond and require more extensive surgery and long-term treatment.


Sheba was referred to an orthopedic specialist for surgical debridement of the bone.  Other potentials could include amputation of the limb. 


We are wishing Sheba full recovery for her long term infectious condition.