Joint Swelling in Dogs

Key Takeaways

Joint swelling is caused by the buildup of fluid or excessive bone growth within a joint.

• This is easily recognizable when a joint is obviously larger than it used to be, or larger by comparison to the same joint on another leg

• Dogs with joint swelling may show signs of lameness, pain when the joint is manipulated, or reduced activity levels

• A dog with joint swelling requires prompt medical attention

• The symptom may be indicative of an emergency if it presents alongside other symptoms such as lethargy or an unwillingness to support their weight with the affected limb

• To identify the underlying cause, diagnostic tests such as  bloodwork, joint fluid analysis, and diagnostic imaging are used

• Treatment depends on the underlying cause, but ranges from supportive care to surgery

A Closer Look: What is Joint Swelling in Dogs?

Joint swelling is uncommon in dogs, but is associated with many conditions ranging from mild to potentially life-threatening.  Swollen joints are always cause for concern, and an affected dog requires prompt medical attention. If a dog is unable to bear weight on a limb, presents with extreme lethargy, fever, or pain when the joint is touched, these indicate an emergency and immediate veterinary assistance is required.

Possible Causes

Joint swelling typically occurs as a result of fluid such as blood, septic fluid, or joint fluid (synovial fluid) building up within a joint’s space. In some cases, tumors or abnormalities of the bone or cartilage cause firm swelling of the joint.

Underlying conditions include, but are not limited to:

Osteosarcoma • Other types of cancer • Chronic CCL injury • Luxating patella • Elbow dysplasia • Joint injuries

• Septic arthritis • Immune mediated polyarthritis • Osteoarthritis • Infectious diseases like Lyme disease

Damage to the structures of the joint through traumatic injury can occasionally cause joint swelling, however these changes are typically mild. Most cases of acute traumatic joint injury, such as rupture of the cranial cruciate ligament, do not show significant joint swelling, despite having serious consequences for joint function and long-term health.

Risk Factors

A dog which has recently suffered a physical injury may have swelling in only one joint. This may result in acute swelling, caused by bleeding, inflammation, or septic fluid buildup in the joint. These cases may result in more sudden, severe, and noticeable swelling.

Chronic swelling is more gradual, and can be initially difficult to notice. Conditions such as polyarthritis can lead to joints swelling over a period of weeks. Chronic swelling is often accompanied by joint pain, and difficulty moving- symptoms which appear intermittently, and increase over time.

The age of onset also increases suspicion of certain conditions over others. Older dogs are more prone to osteoarthritis or tumors, such as osteosarcoma, while younger dogs are more likely to have developmental abnormalities such as osteochondrosis. 

If multiple joints are swollen simultaneously, that implies a systemic illness. In such cases a dog will often also present with lethargy and decreased appetite.

Testing and Diagnosis

A physical examination is often sufficient to recognize the symptom. Diagnostics to identify the underlying cause include:

• Bloodwork • Urinalysis • Diagnostic imaging, such as X-rays or ultrasound • Joint fluid analysis (arthrocentesis)

• Testing for specific infectious diseases • Biopsy of the joint capsule

Treatment depends on the underlying cause. In some cases, symptomatic therapy is sufficient, such as giving the dog anti-inflammatory medication, analgesics, or simply rest and time to recover. Antibiotics may be used in cases of infection, or radiation and chemotherapy in cases of cancer. Surgical intervention is often required to treat many conditions, including elbow dysplasia, osteochondrosis, septic arthritis, and kneecap displacement (among others). 

Over-the-counter pain medication should not be used to treat the symptoms without veterinary prescription, as they mask the symptoms of the condition without treating the cause. Veterinary pain medication should not be substituted by human pain medication, as it may be toxic for a dog.

Similar symptoms

Lameness or joint pain often present similarly to joint swelling. Skin masses may be mistaken for joint swelling. Injuries, such as hematomas (bruises), near a joint may swell, and may also be mistaken for joint swelling due to proximity.

Associated Symptoms

Symptoms commonly seen alongside joint swelling include:

LethargyLameness • Slipping while moving • Reduced appetite/anorexia • Joint pain

• Gingerness/change in (walking) posture

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