Swollen Joints in Dogs: 10 Possible Causes & How to Help 

Dog joint swelling can range from mild swelling that’s invisible to the eye, to severely swollen joints that are clearly enlarged. Causes of swollen joints in dogs include arthritis, cranial cruciate ligament rupture, elbow dysplasia, luxating patella and other common joint health conditions. If you are at all concerned about your dog’s joint health or suspect swollen joints, it is important to seek advice from your veterinarian. Imaging (X-rays, a CT or an MRI scan) is the most accurate way to detect subtle swelling or swelling of deeper joints like the hip. 

Whether you have two legs or four, a swollen joint is usually a cause for concern. As a loving pet parent, if you suspect your pup has swollen joints, you probably have questions, like:

• What causes joint swelling in dogs?
• What are the most common causes of swollen joints in dogs?
• What signs should you be looking out for?
• How urgently does your dog need to see a veterinarian if they do have swollen joints?
• What is the treatment likely to be?

Remember, it’s important to speak to your vet if you do suspect your dog has swollen joints, and to seek support to help them feel better.

This article is intended for informational purposes, it is not a replacement for veterinary advice.

What Does Dog Joint Swelling Look Like? 

• Joint swelling in dogs can range from mild swelling that’s invisible to the eye to severely swollen joints that are clearly enlarged. 
• Visible swelling usually indicates severe inflammation, and these joints often have a rounded appearance. 
• Milder swelling can be difficult to see and is much easier to feel. It’s often easiest to feel the same joint on each side of the body to compare. If the small protrusions of bone around the joint are harder to feel and the soft tissues feel thicker, this usually indicates swelling.
• Imaging (X-rays, a CT or an MRI scan) is the most accurate way to detect subtle swelling or swelling of deeper joints like the hip. 

Where Do Swollen Joints Occur in Dogs? 

Swollen joints can occur anywhere in a dog’s body. However, some are more commonly affected than others. Certain locations of the swelling can make specific conditions more likely. 

• A dog with a swollen joint in their front leg is most likely to have a swollen elbow or wrist (carpus). Arthritis is common in these joints, in addition to elbow dysplasia in younger dogs. In growing puppies, fractures of these joints after a big jump or fall are also possible. 
• A dog with a swollen joint in their back leg is most likely to have a swollen hock (ankle) joint or stifle (knee) joint. The knee is a common site of joint problems and swelling in dogs. Common conditions that should be considered in dogs with a swollen joint in the back leg include luxating patella, cranial cruciate ligament injury, and arthritis. 

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10 Possible Causes of Joint Swelling in Dogs 

1.   Arthritis 

Arthritis means inflammation of a joint. Unsurprisingly, it’s one of the most common causes of joint swelling. Other signs include warmth, pain, stiffness and a crunching sensation when the joint is moved (crepitus). 

It can affect almost any joint in the body, though the most commonly affected are the hip, elbow, lower back, knee (stifle), and wrist (carpus). 

Arthritis commonly affects multiple joints, including the same joint on both sides of the body (but not always). Dogs may also experience a flare-up in a specific joint if they’ve landed awkwardly on one leg, for example. 

While an acute flare-up may cause swelling to become noticeable, arthritis is a chronic condition. Affected dogs are likely to show longer-term signs of stiffness and pain, although these can be subtle in the early stages. 

2.   Cranial Cruciate Ligament (CCL) Injuries 

Cranial cruciate ligament rupture is one of the most common orthopedic problems seen in dogs. 

While it often occurs suddenly during exercise, trauma is rarely the true cause. CCL ruptures typically occur as the end-result of a chronic degenerative process, meaning it’s common for both knees to be affected within a couple of years. 

CCL rupture usually causes sudden, fairly severe lameness and can lead to visible swelling. But partial ruptures and milder clinical signs are seen in some dogs. Some dogs may have chronic, waxing and waning lameness for weeks to months before diagnosis. 

3.   Elbow Dysplasia 

Joint dysplasia is the result of abnormal cartilage development in growing joints. Elbow dysplasia is one of the most common forms and typically affects large or giant breed dogs at around 4 to 8 months of age. 

Elbow dysplasia develops slowly, causing chronic lameness that’s often worse after rest or excessive exercise, and in some cases joint swelling. 

It can also contribute to early-onset arthritis, resulting in longer-term lameness and swelling. 

4.   Luxating Patella 

Patellar luxation is a common cause of knee problems and can cause joint swelling in dogs. 

The patella, or kneecap, usually sits in a groove on the front of the knee and moves smoothly up and down as the knee flexes and extends. However, in some dogs it flicks out of this groove. 

Depending on the severity of the patellar luxation, the kneecap may flick out temporarily with little pain and flick back in after a couple of ‘skipping’ steps, or it may cause more severe lameness. 

Mild patellar luxation may not cause many problems, but more severe cases can cause joint inflammation, swelling, and pain. It can also contribute to the development of arthritis. 

5.   Immune-Mediated Polyarthritis (IMPA) 

IMPA develops when the immune system mistakenly identifies the tissues of the joints as a threat and begins to attack them. 

This typically causes swelling, pain and stiffness across multiple joints, which often develops fairly rapidly. Dogs may develop ‘shifting lameness’ where different legs seem to be affected at different times. They may also have a high temperature, go off their food and seem lethargic. 

IMPA can affect dogs of any age or breed, and in many dogs no specific cause is identified. However, it can occur as a result of an infection, gastrointestinal disease, or cancer. 

6.   Septic Arthritis 

Septic arthritis describes inflammation of a joint due to infection within it and should be considered a medical emergency.

It usually develops after a penetrating injury, such as a bite or other trauma, introduces infection (typically bacterial) into the joint space. Occasionally, infection may develop without trauma due to infection travelling in the blood or immunosuppression. 

Septic arthritis usually affects a single joint and can cause significant pain and swelling. Dogs may also develop a fever and be generally unwell. This condition is a medical emergency, as the infection can rapidly progress and cause permanent damage to the joint. 

7.   Lyme Disease 

Lyme disease is one of the most common diseases transmitted by ticks. It can cause vague, non-specific signs, making it challenging to diagnose. 

One of the most common symptoms is recurrent, shifting lameness that can vary between legs over days to weeks. Affected joints can be swollen, warm, and painful. 

Other symptoms include lethargy, swollen lymph nodes, and poor appetite. Some dogs may develop kidney issues, leading to excessive drinking and urination. 

8.   Dislocations & Fractures 

These are usually caused by trauma and – unsurprisingly – often cause severe pain and swelling. 

However, they can be sneakier than you might expect. Relatively minor bumps and falls can cause a fracture in a puppy. And while we often think of fracture causing severe lameness, some dogs with fractures or dislocations may continue to walk on the affected leg. 

It’s important to treat a dislocation or fracture sooner rather than later. If your dog develops sudden joint swelling and pain after any kind of trauma, it’s always worth getting them checked. 

9.   Cancer 

Unfortunately, cancer can affect almost any part of your dog’s body. That includes the bones and joints. The most common types are osteosarcoma and chondrosarcoma, both of which can cause gradually developing lameness and firm swelling around a joint. 

Bone cancers tend to be very aggressive and can eventually cause severe pain. They can also predispose dogs to so-called ‘pathological’ fractures, caused by only mild trauma. Other signs include lethargy and weight loss. 

These cancers are most commonly seen in older dogs belonging to large breeds, such as Rottweilers, Great Danes and Golden Retrievers. 

10. Bleeding 

Rarely, dogs can develop ‘hemarthrosis’, or bleeding into a joint. This can be caused by trauma but is also seen in dogs with bleeding disorders, including those that have ingested rat poisoning 

Swollen Dog Joints FAQ

Q: How Do Vets Test For Swollen Joint Issues in Dogs?

Your veterinarian may recommend a range of investigations to get to the bottom of your dog’s joint swelling. Which tests are needed and in what order depends on your dog’s history and clinical signs. 

Sometimes a combination of a thorough history and clinical examination is enough to give your vet a strong suspicion of the likely cause. Videos of your dog walking from the side and from behind can be helpful for your vet to pinpoint the cause of swollen joints in dogs. 

• Blood tests – Blood tests can give a good overview of how any disease is affecting your dog’s organs and how your dog’s body is responding. More specialised tests for Lyme disease, clotting times, or parasites that can contribute to bleeding disorders may also be recommended. 
• Imaging – Radiographs (X-rays) can diagnose some causes of joint swelling. More detailed imaging with a CT or MRI scan may be recommended for more complex cases. 
• Joint tap (arthrocentesis) – To diagnose conditions like septic arthritis and IMPA, a sample of joint fluid can be collected in a sterile manner. This is then assessed under the microscope and cultured to identify any infection. 

Q: What Treatments Are There for Swollen Joints in Dogs?

The right treatment for swollen joints in dogs depends on the cause. With so many potential causes, it’s definitely not one-size-fits-all. Possible treatments include:

• Activity modification, ranging from crate rest to restricted walks 
• Anti-inflammatories and other pain relief 
• Supportive treatments such as physiotherapy and hydrotherapy
• Weight management. This is crucial for pets with arthritis, elbow dysplasia and other long-term joint conditions 
• Surgery to treat conditions such as cruciate ligament rupture, fractures and patellar luxation 
• Antibiotics to manage septic arthritis or Lyme disease 
• Immunosuppressive medications to treat immune-mediated polyarthritis 

Q: How Do I Support My Dog’s Joint Health?

Your veterinarian is the best person to give you personalized advice on both the treatment of your dog’s swollen joints and things you can do at home to support their recovery. 

Once any swelling has gone down and your vet has given your dog the all clear, there are some simple steps you can take at home to help support their joint health.

1. Adjust their exercise routine: For dogs with elbow dysplasia, patellar luxation, arthritis and other conditions, sticking to regular gentle exercise can make a world of difference. Work out a level of exercise your dog is comfortable with and stick to it. 
2. Switch out the ball thrower: Unfortunately, dogs are prone to overdoing it when playing games like fetch and frisbee. Sudden, twisting leaps in the air and abrupt stops to catch the ball can put a lot of strain on their joints. Try scent work, puzzles, and training tricks instead. 
3. Keep Your Dog at a Healthy Weight: With around 50 percent of dogs now overweight or obese, excess weight has become the norm. But this extra weight impacts almost every body system, including your dog’s joints. Whatever stage of life your dog is at, helping them to maintain a healthy weight is key to looking after their joints. 

Final Thoughts: Swollen Joints in Dogs

Swollen joints in dogs can be caused by a range of underlying conditions, from arthritis to dislocations and injuries. It’s important to seek support from your veterinarian if you suspect swollen joints are affecting your pup’s comfort and wellbeing. Taking steps to support your dog’s long term joint health is also important, such as maintaining a healthy weight and an active lifestyle.

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