Septic arthritis in dogs (infectious arthritis) is a specific type of inflammatory arthropathy triggered by an infective agent, more often than not – bacteria.
The presence of an infective agent (bacteria) makes the importance of early diagnosis and prompt treatment of imperative importance.
However, because of the non-specific clinical signs of septic arthritis, it can be hard for dog owners to react in a timely manner.
To stay on the safe side, dog owners should seek veterinary attention as soon as they notice lameness, joint swelling, and decreased playfulness as these are the red flags for joint infections.
What is Septic Arthritis in Dogs?
Septic arthritis in dogs is a specific type of joint disease, popularly known as toxic inflammation of the joints or infectious arthritis.
Septic arthritis can be differentiated from regular arthritis by the lack of disease-causing microorganisms (bacteria, fungi, or viruses) within the synovial fluid.
In a dog with osteoarthritic joints, the joint damage is of inflammatory nature. In a dog with infected joints, the joint damage is caused by infection followed by inflammatory changes, joint effusion, joint swelling, pain, and lameness.
While regular arthritis is usually associated with old age and has a gradual onset, septic arthritis can occur in any dog suddenly and with more severe clinical signs.
Causes of Septic Arthritis
Septic arthritis in dogs is always associated with a disease-causing microorganism present in synovial fluid. Based on results from culture and sensitivity testing, the most common infection culprits include:
- Bacteria (Streptococcus pyogenes, Staphylococcus aureus, Pasteurella, Klebsiella, and Chlamydophila)
- Rickettsia (Rocky Mountain Spotted fever, Ehrlichiosis)
- Spirochetes (Borreliosis)
The bacteria and other infectious agents can find their way into the synovial fluid via several routes:
- Penetrating trauma associated with the joint
- Joint or bone surgery
- Intraarticular injections (injections inside the joints)
- Hematogenous spread (if the infection spreads from another source via blood, like skin infection or kidney infection).
According to a review study from 1999, “Bacterial septic arthritis in 19 dogs,” published in the Aust. Veterinary J. only five of the 19 dogs developed septic arthritis due to a hematogenous spread, while the other 14 dogs after surgical procedures associated with the stifle joint.
Another article study from 2003, “Septic Arthritis in Dogs: A Retrospective Study of 20 Cases (2000-2002),” published in Acta Vet. Brno revealed that the hematogenous spread of bacteria resulted in infected joints in 13 cases and only seven cases were due to joint surgery and joint trauma.
From the two review articles, we can assume that both infection routes are common reasons for septic arthritis.
Septic Arthritis in Dogs – Risk Factors and Predispositions
Several risk factors can make a dog more likely to develop septic arthritis, including:
- Diseases that cause immune suppression, like Addison’s disease or diabetes mellitus
- Immunosuppressive drugs
- Trauma involves the joints
- Surgical procedures involving the joints
- Injections into the joints
- Osteoarthritis and other associated forms of degenerative bone and joint disease.
All dogs can develop septic arthritis. However, in practice, infectious arthritis is most commonly reported in male dogs from large and giant breeds.
Affected dogs are usually between three and eleven years old. Once again, this is a statistical record. In theory, dogs of all ages can develop septic arthritis.
Septic arthritis also has a breed predisposition – it is prevalent among Labrador Retrievers, German Shepherds, and Dobermans.
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Symptoms of Septic Arthritis
Septic arthritis in dogs manifests with the following clinical signs and symptoms:
Not all signs of septic arthritis need to be present. Some dogs may show only lameness and decreased range of motion, while others can show more severe clinical signs of septic arthritis like fever and depression.
In all septic arthritis cases, the clinical signs and symptoms are non-specific thus making the diagnosis challenging.
Septic Arthritis Diagnosis
When a dog manifests lameness and fever as clinical signs, the veterinarian will suspect septic arthritis. However, the veterinarian can set the infectious arthritis diagnosis after a full and thorough examination.
Setting the septic arthritis diagnosis starts with the veterinarian taking a detailed history (previous joint damage, injuries, illnesses, surgical procedures) and performing a full body examination.
The history will help the vet review how the joint issue developed, and the physical examination helps determine how many joints are affected.
Then, the veterinarian will order laboratory tests – blood analysis (complete blood count and biochemistry profile) and urinalysis.
In a dog with septic arthritis, the biochemistry profile and urinalysis examination are usually normal, while the blood count is likely to indicate inflammation and infection in the blood.
The next step is x-ray imaging of the affected joint or joints. In dogs with chronic septic arthritis, the imaging will show many signs of joint damage, including irregular joint space, joint effusion, bone destruction, and abnormal bone formation.
Generally speaking, in early cases of septic arthritis in dogs, the radiography will reveal signs of joint effusion. In chronic joint infection cases, the imaging show signs of advanced degenerative joint disease.
Popularly known as joint tap, arthrocentesis is a diagnostic procedure that involves taking synovial joint fluid samples and then analyzing the samples.
The synovial fluid samples are routinely examined under a microscope. In some cases, the synovial fluid examination can be done by a veterinary pathologist.
An article study from 2017, “Preanalytical Considerations for Joint Fluid Evaluation,” published in the Veterinary Clin. North Am. Small Anim. Pract. revealed that performing a synovial fluid analysis is a crucial diagnostic procedure in any joint disease case.
Taking joint fluid samples is considered a minimally invasive procedure, and it is performed using a sterile needle and an empty syringe.
Based on an article study from 2020, “Influence of clipping on bacterial contamination of canine arthrocentesis sites before and after skin preparation,” published in Vet. Surg. the veterinary technician should aseptically prepare the arthrocentesis sites before collecting the samples.
Although minimally invasive, taking synovial fluid samples is a quite painful diagnostic procedure and should be performed under sedation. Full anesthesia is rarely recommended. It should be noted that in a dog with severe signs of septic arthritis inducing anesthesia can be risky.
Bacterial Culture and Sensitivity Testing
Bacterial culture and sensitivity testing are the key aspects of septic arthritis diagnosis and treatment.
As diagnostic examination procedures, the bacterial culture and sensitivity testing will help the veterinarian confirm the presence of infectious bacteria and determine the exact bacteria type. Knowing the exact bacteria type responsible for the joint infection is vital for determining the right antibiotics.
Bacterial culture and sensitivity testing should be performed on every dog whose clinical signs and symptoms include lameness, joint pain, and fever.
Depending on the severity and the dog’s overall health, some dogs with infectious arthritis may require hospitalization. The treatment for dogs with arthritis (septic) has two goals:
- Preventing further damage to the infected joint
- Addressing the infection
To prevent further joint damage, the vet will perform a joint lavage. However, in more severe chronic cases, the veterinarian will have to surgically open the affected joint, remove the abnormal tissue and debris and make a copious joint lavage.
If necessary, the vet will place a catheter and use the catheter to perform post-operative joint lavage.
A review article from 2016, “Surgical management of septic arthritis,” published in Veterinary Clin North Am. Food Anim. Pract. revealed that lameness due to synovial fluid infection warrants immediate veterinary attention and management.
If the treatment is delayed, permanent joint damage is possible. In more severe cases, the infection can spread and cause osteomyelitis. Osteomyelitis is a rare but severe infection and inflammation associated with the bone and bone marrow.
While waiting for the bacterial culture and sensitivity panel results, the vet will probably give broad-spectrum antibiotics. When the bacterial culture and sensitivity testing results are ready, the vet will decide whether the prescribed antibiotics work or alternatively recommend other oral antibiotics.
In most cases, the course of the oral antibiotic lasts for a couple of weeks (usually 4 to 8 weeks). If the dog is in severe pain, the veterinarian will recommend an oral non-steroidal anti-inflammatory drug to manage joint swelling, pain, and inflammation.
After being released from the hospital, dogs with joint lavage or surgical joint repair benefit from cold and heat packs, which promote blood flow in the affected joint, thus reducing joint swelling and inflammation.
The vet will also recommend cage rest and restricted activity for several weeks. How long the restrictions will last depends on how severe the joint infection was and whether surgery was performed.
A review article study from 1999, “Bacterial septic arthritis in 19 dogs,” published in the Aust. Veterinary Journal revealed that only five of the arthritic dogs were treated with broad-spectrum oral antibiotics. The other 14 dogs received antibiotics and had joint lavage with or without surgery on the infected joint.
The performed surgical corrections of the affected joint included:
- Removal of non-absorbable suture material (placed during a previous surgery that likely triggered the infection) – in eight cases
- Arthrodesis (surgical removal of the joint and making an artificial bone-to-bone connection)– in two cases
- Amputation (surgical removal of the limb with an infected joint) – in one case
Because of the severity of the joint damage and associated clinical signs, two dogs were euthanized. The other seventeen dogs responded to therapy and surgery and eliminated the infection completely.
Septic arthritis may become a chronic issue, so dogs need to be closely monitored for joint pain and swelling return.
To ensure the infection is all cleared, the veterinarian will probably recommend frequent joint fluid evaluations for several weeks. The joint fluid analysis will also help the vet determine the dog’s response to the treatment.
To speed up the healing and prevent joint degeneration, the veterinarian will probably advise physical rehabilitation and holistic management approaches.
In a dog with septic arthritis, follow-up care is vital as it is at high risk of developing:
- Degenerative joint disease and joint damage
- Bone infections (osteomyelitis)
- Limited range of motion (in the affected joint)
- Generalized infection (the infection may spread and cause systemic issues).
Holistic Ways to Help Your Dog Through Treatment
The acute signs of septic arthritis warrant immediate veterinary attention and aggressive management involving antibiotics and surgical management.
However, there are ways you can help your dog through septic arthritis treatment. When it comes to the holistic management of arthritis (septic), there are two main considerations for your dog.
Dog CBD Oil
The use of CBD oil in veterinary medicine is new but shows promising results. CBD oil is a natural, herbal supplement that can help dogs with septic arthritis during treatment and recovery.
CBD oil promotes healthy bones and joints and supports flexibility and a full range of motion while easing joint stiffness and occasional discomfort due to daily exercise and activity.
You can give your dog CBD oil in its food or use CBD-infused chewable treats. It should be noted that before adding anything new to your dog’s therapy plan you need to consult with your trusted vet.
Physical therapy is a particularly helpful yet frequently neglected way of managing a dog after septic arthritis treatment.
Physical therapy is important to maintain proper joint mobility since regular physical activity will be limited for at least a few weeks after treatment.
There are different physical therapy options. However, dogs with septic arthritis benefit most from passive range of motion (PROM) exercises.
Our Final Thoughts
As an inflammatory arthropathy, septic arthritis warrants immediate veterinary attention and adequate antibiotic therapy with or without surgical joint debridement.
Even with a prompt and aggressive approach, the prognosis is variable and depends on the original disease and the chronicity of the infection.
Dog owners should be informed that a complete return to normal joint function is very unlikely, especially in chronic cases because of the joint damage extent. The joint function return is also questionable in overweight dogs.
All in all, the treatment is successful but in terms of infection elimination. As for the full joint function restoring the prognosis is guarded.
Frequently Asked Questions
What causes septic arthritis in dogs?
Infectious arthritis in dogs is caused by disease-triggering microorganisms (bacteria, fungi, virus) introduced into the synovial fluid at the time of joint surgery or penetrating joint injury or reaching the synovial fluid by hematogenous spread (via the blood).
What is the most common cause of septic arthritis?
In dogs, the most common cause of septic arthritis is surgery involving the stifle joint. The infection is most frequently associated with bacteria like staphylococci, streptococci, and coliforms.
How do you treat a septic dog?
The treatment for infectious arthritis includes broad-spectrum antibiotics (oral and/or injectable), joint lavage, and surgical debridement. Some dogs can be treated solely with antibiotics, while others need more complex treatment.