What Role Does Inflammation Play in Canine Osteoarthritis?

Osteoarthritis in dogs is a painful, progressive condition that results in deterioration of the joints. It develops most commonly due to underlying joint abnormalities, joint injury, or normal aging. Osteoarthritis symptoms in dogs include reduced range of motion, limping, stiffness, joint swelling, and pain. Inflammation plays a key role in this disease process, which is why non-steroidal anti-inflammatory drugs (NSAIDs), such as Galliprant, are widely used for treatment.

Let’s discuss the role of inflammation in canine osteoarthritis (also known as OA or simply arthritis), as well as medications to combat pain and inflammation in affected dogs.

Osteoarthritis in Dogs: What Role Does Inflammation Play?

Normal wear and tear of the joints causes a dog’s body to release certain enzymes that break down cartilage. Cartilage is a type of connective tissue that protects the bones. As this cartilage wears down over time, the bones begin to rub against one another. This friction leads to joint changes, such as the development of bone spurs, as well as significant pain and inflammation. Fluid builds up within the joint, causing visible swelling. Inflammatory cells and other proteins are released to further damage the joint. Unfortunately, once the cartilage has broken down, it is difficult to repair. Therefore, osteoarthritis in dogs continues to progress in severity without appropriate treatment. 

So how important is inflammation in this process? Even though osteoarthritis in dogs is a degenerative disease, inflammation is likely a critical component. Inflammation has long been considered a symptom of osteoarthritis rather than a cause. However, once inflammation is present within the joint, degeneration quickly progresses. This has led to ongoing research as to whether inflammation plays a more prominent role in osteoarthritis than previously thought. 

Studies have shown that the fluid within the joints (synovial fluid) of dogs with osteoarthritis has significantly increased levels of several types of proteins called cytokines. The body makes cytokines in response to inflammation. These cytokines are considered pro-inflammatory, and they activate the dog’s immune system to produce more inflammatory cells. This results in further damage within the joints and progression of osteoarthritis. In turn, dogs with arthritis experience more pain and reduced range of motion in their affected limbs (1,2,3).

Similarly, prostaglandins are a type of lipid produced in response to inflammation. When high levels of prostaglandins are found in joints, the lining of the joint (synovium) becomes inflamed in a process known as synovitis. As a result, the cartilage breaks down, causing pain. This, in turn, leads to more prostaglandin production. The affected joint is essentially stuck in a vicious cycle of inflammation and progressive deterioration (4). 

Although these studies suggest that osteoarthritis may actually be an inflammatory disease, research is still ongoing to study the exact role inflammation plays and the various immune cells that are involved in osteoarthritis and its progression in dogs.

Osteoarthritis in Dogs Treatment: Controlling Pain and Inflammation

Controlling both pain and inflammation is the main goal of osteoarthritis in dogs treatment. Treating pain relieves discomfort for dogs, while treating inflammation slows the progression of the disease. Some medications for treating osteoarthritis in dogs simply mask pain and do not target inflammation at the source. Unfortunately, this form of treatment does nothing to prevent or slow continued deterioration of the joints. 

NSAIDs are the first-line dog arthritis medicine because they target inflammation while controlling pain. Most NSAIDs work by blocking enzymes that produce prostaglandins. By inhibiting prostaglandin production within joints, pain and inflammation are reduced. 

However, a unique NSAID known as Galliprant actually controls pain and inflammation in dogs with osteoarthritis by targeting one specific prostaglandin receptor (rather than the enzyme like other NSAIDs do). Galliprant effectively targets inflammation directly at the source and slows progression of joint damage while minimizing negative effects on the dog’s body. It is widely used among veterinarians and well-tolerated among most dogs. 

Although osteoarthritis in dogs is a painful and progressive condition, controlling inflammation has substantial positive effects on a dog’s comfort while also slowing disease progression. Beginning treatment early provides the best opportunity to promote joint health and mobility. If your dog has been diagnosed with osteoarthritis, closely follow your veterinarian’s instructions for using prescription medications for the best prognosis. 

References

1. Carter, S D et al. “Canine rheumatoid arthritis and inflammatory cytokines.” Veterinary immunology and immunopathology vol. 69,2-4 (1999): 201-14. doi:10.1016/s0165-2427(99)00054-9
2. de Bakker, E et al. “Detection of osteoarthritis in dogs by metabolic, pro-inflammatory and degenerative synovial fluid biomarkers and traditional radiographic screening: A pilot study.” Veterinary immunology and immunopathology vol. 237 (2021): 110252. doi:10.1016/j.vetimm.2021.110252
3. Alves, J C et al. “The influence of IL-1 and C-reactive protein levels in synovial fluid of companion dogs with bilateral hip osteoarthritis on various clinical disease parameters.” American journal of veterinary research vol. 83,11 1-10. 13 Sep. 2022, doi:10.2460/ajvr.22.05.0079
4. Yang, Dinglong et al. “Revisiting prostaglandin E2: A promising therapeutic target for osteoarthritis.” Clinical immunology (Orlando, Fla.) vol. 260 (2024): 109904. doi:10.1016/j.clim.2024.109904