Osteomyelitis in Dogs

What is Osteomyelitis in Dogs?

Osteomyelitis is inflammation of the bone and/or bone marrow due to a bacterial or fungal infection. It can occur when infection enters the bloodstream and spreads to surrounding structures, including the bone. Infection can also be directly introduced into the bone from a traumatic injury such as a fracture, or a deep, penetrating wound. Most often, osteomyelitis affects the limbs and the jaw.

This is a serious condition that can destroy the bone, and prompt treatment is necessary. Unfortunately, osteomyelitis can be difficult to treat and often requires long-term management, depending on the severity and cause.

Types of Osteomyelitis in Dogs

This condition can occur suddenly (acute) or develop slowly over time (a chronic condition that may occur over months). Infection can be bacterial or fungal:

• Bacterial osteomyelitis is the most common type of infection, including Staphylococcus spp. and Streptococcus spp. These are types of bacteria that can normally be found on the skin of healthy dogs. Other forms of bacterial infection include E. coli, Pseudomonas, and Pasteurella, which are species of bacteria considered to be mostly environmental contaminants.
   
• Fungal osteomyelitis is rare, and the type depends on where the dog lives. For example, dogs residing in Mississippi, Missouri, and Ohio River valleys are more likely to be exposed to Histoplasma capsulatum in soil that contains bat or bird droppings. Other types of fungal organisms, such as Aspergillus spp. can be encountered worldwide.

Causes of Osteomyelitis in Dogs

Causes of this condition include the following:

• Systemic infection: Infections occurring elsewhere in the body can migrate to the bone through the bloodstream. An example would be a hunting dog inhaling fungal spores found in the soil into its lungs.  Dogs with impaired immune systems are more at risk.

• Traumatic injury: Fractures that expose the bone can lead to contamination with bacteria or fungal organisms found normally on the skin, or in the surrounding environment.

• Bites or punctures: Wounds due to deep penetration by a foreign object, such as a gunshot injury.

• Post-surgical issues: Following orthopedic surgery for metal implants, osteomyelitis may occur if there are underlying complications. Types of implants include bone plates, screws, and rings.

• Dental disease: Oral tumors can invade the jaw and cause infection, as well as severe periodontal disease (dental decay).

Viruses have not yet been found to be a cause of osteomyelitis in dogs.

Symptoms of Osteomyelitis in Dogs

Infection and inflammation within the bone can produce signs specific to the infected area or throughout the body, including:

• Lameness

• Pain/discomfort

• Swelling of the affected area

• Visible wounds that may appear infected

• Fever

• Lack of energy  

• Depression and weakness

• Decreased appetite 

Symptoms can vary widely depending on the areas affected. For example, a dog with bone infection in the jaw may also experience pain while eating and have halitosis (foul-smelling breath).

How Veterinarians Diagnose Osteomyelitis in Dogs

At the initial appointment, your veterinarian will take a detailed medical history of your dog, ask questions regarding any recent travel, and a precise timeline of the onset of symptoms.

A thorough medical history will allow your veterinarian to determine if this is an acute or chronic infection, and whether it is more likely to be bacterial or fungal in origin. A thorough physical examination will be performed. 

Your veterinarian will recommend diagnostic testing to determine the areas of bone involved and severity of the infection present. Tests will include a CBC (complete blood count), serum chemistry profile, and a urinalysis. The lab work results will likely show an elevation in white blood cells, among other changes associated with an active immune response. 

Imaging studies such as X-rays will provide a more detailed picture of the underlying bony changes that may have occurred. Fungal and bacterial cultures can also be performed to identify the organism and guide treatment for your dog. 

Specialized testing may be recommended in more severe cases of osteomyelitis, including ultrasound imaging and a surgical bone biopsy. Referral to a veterinary specialist may also be recommended for your pet to help manage more complicated infections.

Treatment of Osteomyelitis in Dogs

Your veterinarian will determine the most appropriate treatment for your dog based on the medical history, initial physical exam, and subsequent tests.

Hospitalization for treatment and supportive care may be recommended. Any wounds will be treated, and fractured limbs will be stabilized. To treat osteomyelitis, the veterinarian staff may do the following, depending on the type and severity:

• Medications: The type of underlying infection, and results of any cultures performed, will determine if an antibiotic or antifungal medication is to be prescribed. Medication may be delivered by IV, orally, through the skin, or a combination of these applications. A course of long-term medication may be administered for four to six weeks.
• Surgery: More severe cases of osteomyelitis may require surgical intervention. For example, dead tissue (necrotic) in large and extensive wounds may need to be excised. Surgical implants that have failed will need to be removed. Complex fractures also require stabilization and repair under general anesthesia.

Recovery and Management of Osteomyelitis in Dogs

With appropriate therapies and support from your veterinarian, osteomyelitis can be successfully treated, and your dog can make a full recovery. However, the overall prognosis will depend on the cause, duration and severity of the infection, and the extensiveness of any wounds, trauma, or present injury.

All discharge instructions and medication directions from your veterinarian will need to be strictly followed. It is important to complete the full course of any antibiotic or antifungal prescribed. Regular follow-up appointments are to be expected, and additional diagnostics such as lab work and imaging will likely be performed to assess if proper healing is taking place.

To help promote a successful treatment outcome at home, your veterinarian may recommend lifestyle modifications, including prolonged cage rest and activity restrictions, basic wound care management, and nutritional and supplemental therapies

Prevention of Osteomyelitis in Dogs

The most important way to prevent this condition is to seek immediate attention. If there are any wounds, trauma, or injuries—or if any signs of systemic illness—such as fever, lethargy, weakness or decreased appetite, see a veterinarian immediately.  If your dog has undergone an orthopedic procedure involving metal implants, it is critical to keep your veterinarian notified of any changes in health status. Prompt diagnosis and treatment of osteomyelitis is critical to promote a successful outcome.

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