inflammation of the bone and its marrow is known as osteomyelitis. Different causes can cause bacteria or fungi to reach your dog's bones and trigger the process, either by infections in the body that go to the bone through the blood, or by external microorganisms that arrive through contamination, trauma or wounds. In any case, it is an annoying and painful disease for your dog whose treatment usually lasts several weeks or even months, depending on the type of osteomyelitis and its severity.
The long bones are the ones that are usually affected, such as the femur, humerus, tibia and ulna. It can also occur in the spine or cause a dental osteomyelitis In this article on our site, we will discuss osteomyelitis in dogs, its symptoms, diagnosis and treatment.
What is osteomyelitis in dogs?
This is an inflammatory disease of the bone and bone marrow of infectious origin that causes progressive destruction of bone tissue due to the arrival mainly of bacteria in these areas, triggering an inflammatory process
Despite the fact that bone itself is resistant to infection, this disease produces defects in the blood supply due to enzymes that release microorganisms that trigger bone ischemia and necrosis, favoring the cantonment of microorganisms and the development of the disease. Mainly, its origin is bacterial, and bacteria can arrive as a result of bites, wounds or fractures, among others. It can also be caused by a fungal infection, but usually occurs as a result of a generalized fungal disease.
Causes of osteomyelitis in dogs
As we have mentioned, in most cases of canine osteomyelitis the origin is bacterial. According to their frequency, the bacteria involved in the process are:
- Frequent microorganisms: Staphylococcus aureus, responsible for more than 50% of cases of osteomyelitis in dogs.
- Less frequent microorganisms: Streptococcus app., Enterococcus spp., Pseudomonas spp., Enterobacter spp., Proteus spp., Escherichia coli and Serratia spp.
- Rare microorganisms: Mycobacterium tuberculosis, Mycobacterium avium complex mycobacteria candida spp., Mycoplasma spp., Brucella spp., Salmonella spp. and Actinomyces.
Cases caused by fungi occur much less frequently and are caused by systemic fungal diseases, such as aspergillosis, blastomycosis or cryptococcosis.
Infection entry route
Osteomyelitis in dogs are usually caused by external causes (more than 70% of cases), rather than being transmitted via blood, this being more frequent in puppies. In this way, depending on the arrival of the microorganism to the affected bone, the route of entry can be of four types:
- Hematogenous: Osteomyelitis rarely occurs by this route from an infectious focus far from the bone, such as in the bladder, lung or skin, being more frequent in puppies under one year of age and in male dogs of large breeds. In the newborn puppy, septicemia is produced from a focus of umbilical infection that allows bacteria to enter through the arteries that supply the long bones, becoming trapped in the arteries and capillaries of the metaphysis of the bones (the middle part of the bones).) at the level of the epiphyseal plate (or growth plate), causing thrombi with loss of blood supply and necrosis, migration of leukocytes (white cells of the immune system) and pus formation inside the bone. Osteomyelitis by this route can be directed to the nearest joint, producing septic arthritis (joint infection) that must be treated urgently. The main bones affected are the femur, humerus and vertebrae (discospondylitis). This form is usually caused by Staphylococcus aureus, although it can also be caused by E. coli, Proteus spp. and Streptococcus spp. Rarely, discospondylitis can be caused by Brucella, increasing suspicion if the dog maintains contact with ruminant animals or is farmed.
- Post-traumatic: due to external damage such as bites from other animals, open fractures, gunshots or puncture wounds.
- Tissue contiguity: such as when there is an infection in the dog's mouth and it spreads to the teeth causing dental osteomyelitis or infections of skin, such as chronic deep pyoderma or otitis media.
- Iatrogenic: due to contamination from trauma surgery, because when a bill is surgically fixed, the implants that are placed in the affected bones are a focus for bacterial colonization if asepsis has not been strict, as well as if open trauma has been operated where the germs have already penetrated the tissues.
Symptoms of osteomyelitis in dogs
In osteomyelitis, the bone initially responds by becoming inflamed and the surrounding soft tissues will be hot, red, swollen and painful. Depending on its course and origin, it can be acute with systemic signs or chronic without hematological alterations:
Acute osteomyelitis in dogs
This presentation is the most frequent, where the following clinical signs occur:
- Fever.
- Anorexy.
- Weightloss.
- Incrise of cardiac frecuency.
- Increased white blood cell count (mainly neutrophils).
- Pain and bone swelling due to purulent infection.
- Edema of tissues near the injury with pain on palpation and movement of the affected limb.
- Blood vessel congestion.
- Thrombosis (clots) in small vessels.
Chronic osteomyelitis in dogs
This clinical form has a longer course, with clinical signs such as:
- Secretion through fistulae at the site of injury.
- Limp.
- Muscular atrophy.
- Enlargement of nearby lymph nodes.
- Formation of bone sequestration (segment of dead bone that is separated from living bone by granulation tissue).
- Bone tissue with persistent infection.
Diagnosis of osteomyelitis in dogs
The diagnosis of this disease is made mainly by radiography, but the patient's history, as well as the examination of the area and its analysis, are indicative of a bone infection. So the diagnosis that your veterinarian will make will be clinical and radiological:
Clinical Diagnosis
It is based on doing the following:
- Medical history: previous fractures, bites, foreign bodies, run over…
- Physical examination: detect swollen areas in the teeth, long bones, spine indicative of a possible bone infection, as well as fever, lethargy, weakness and anorexia.
- Blood test: to find changes indicative of an infectious process such as leukocytosis (increased white blood cells).
- Analysis of the purulent exudate: with culture and antibiogram to know which is the causal agent and which antibiotic is sensitive to plan medical treatment.
Radiological diagnosis
X-ray is the easiest and cheapest imaging technique to diagnose this disease. However, for bone changes to be seen on radiography, there must have been a 30-50% decrease in bone density, which occurs between 10 and 21 days from the onset of the injury(5 to 10 days in puppies). Nearby muscles and soft tissues are the first to be affected. The following changes can be seen on the radiograph:
- Bone lysis (destruction of bone due to infection).
- Periosteal proliferation (new bone formation).
- Sequestration bone.
- Bone resorption (bone decalcification).
Treatment of canine osteomyelitis
The treatment of osteomyelitis in dogs is based on a surgical one in both acute and chronic cases and on a medical treatment with antibiotics or antifungals, depending on the cause that originates it.
Surgical treatment of acute osteomyelitis
The infectious focus must be debrided by removing dead, damaged and infected tissue and washing it abundantly. If the problem has been that it has become infected due to an implant, it must be removed, stabilizing the fracture with external fixators that do not cross the focus of bone infection.
Surgical treatment of chronic osteomyelitis
The objective is to eliminate the bone sequestrations, treat the area and carry out a thorough washing to remove all dirt. If it is a non-consolidated fracture and the implants are intact, they should be left but frequently monitored by X-rays of the area and removed when the injury is consolidated. Amputation of the affected limb is recommended only in the most severe cases.
Antibiotics for dogs with osteomyelitis
Antibiotherapy is a mandatory treatment for canine osteomyelitis of bacterial origin. The antibiotic chosen will be the one indicated by the antibiogram, but as a general rule for bacteria such as Staphylococcus, Streptococcus, Enterococcus, Actinomyces or Mycoplasmas, antibiotics such as amoxicillin are usually useful -clavulanate or ampicillin. In contrast, in bacteria such as Pseudomonas spp., Serratia spp., E. coli, Salmonella spp., Brucella and Proteus spp., ciprofloxacin or third generation cephalosporins have more effect.
The antibiotic indicated by the antibiogram is usually apply punctured during the first week and then your dog will take it fororally for 4 or 5 weeks more in acute cases; in chronic cases it can last up to six months.
If your dog has trouble taking his medication, we encourage you to read this other article on Tricks for giving pills to dogs.
Prognosis of osteomyelitis in dogs
It will depend on the cause that originated it, the severity, if it was due to a fracture that had to be operated on by placing an implant for its stabilization and the individual response of each dog. The best thing you can do for your dog to recover as soon as possible is to keep him in a quiet place, away from stress, conflicts with people or other animals, and to be properly fed and hydrated and to follow the treatment guidelines indicated by the veterinary center.
