By: Michael Ephraim Vergara, DVM, Technical Services Associate  

Osteoarthritis (OA) is one of the most common arthritis cases among pets, affecting a quarter of the population of dogs as mentioned in an article published by American College of Veterinary Surgeons.1 While in another publication it says that it has been

estimated that around 30-50% of dogs and cats will be affected by osteoarthritis at some point in their lives.²

By definition, osteoarthritis (OA) is a slowly-progressive degenerative joint disease characterized by a loss of joint cartilage and the subsequent exposure of subchondral bone. This eventually results in a self-perpetuating insidious disorder characterized by joint pain. New bone formation occurs in response to chronic inflammation and local tissue damage in an attempt to limit both movement and pain. Macroscopically, there is a loss of joint cartilage, a narrowing of the joint space, sclerosis of subchondral bone, and the production of joint osteophytes.³

In a publication by Mele (2007), he discussed comparing OA in man and in animals. OA is said to be the most common arthropathy in man and animals, being more frequent in dogs than in cats. In humans, the prevalence in women is two-fold higher than in men, and its incidence increases after 60 years of age. In dogs, the onset of primary OA depends on the breed. The onset mean age is 3.5 years in Rottweilers and 9.5 years in Poodles.³

Data published from the study of Mele (2007) showed the following risk factors in canine osteoarthritis:³

Signalment

- Age: >50% of arthritis cases are observed in dogs aged between 8-13 years. The musculoskeletal diseases are very common in geriatric patients, and nearly 20% of elderly dogs show orthopedic disorders. In Labrador Retrievers aged >8 years, OA in several joints (elbow, shoulder, hip, knee) is typical

- Sex: In general, OA is often associated with primary disorders, which may be more prevalent in males than in females. For example, the fragmentation of the coronoid process is observed in a 3:1 male: female ratio

- Size:  45% of dogs with arthritis are large breed dogs. Among these, >50% are giant breed dogs, while only 28% are medium breed dogs and 27% are small breed dogs.

- Genetic predisposition: Certain breeds, such as Labrador retriever and German shepherd dogs are predisposed to develop arthritis, over and above the prevalence of underlying joint disease in these breeds. 

Obesity and overfeeding especially during the puppy stage and osteoarticular trauma from surgeries, excessive vigorous training have been recognized as well as predisposing factors.³

Generally, the signs of osteoarthritis include lameness, joint swelling, wasting away of muscle, and thickening and scarring of the joint membrane. Eventually, enough damage can occur that a grating sound might be heard during joint movement. X-rays show increased fluid within the joint, soft-tissue swelling around the joint, the formation of bony outgrowths, hardening, and thickening of bone beneath the cartilage, and sometimes a narrowed joint space.⁴

Treatment recommendations for OA are multimodal which means they include different approaches and can be either conservative or surgical or a combination of both. All treatment decisions are made based on individual patients and in discussion with the animal owner and surgeon.¹

Here are some of the most commonly used approaches:¹

• Nonsteroidal anti-inflammatory drugs (meloxicam, deracoxib, ketoprofen, carprofen etc.).
• Adjunctive pain medications (amantadine, gabapentin, tramadol, codein, corticosteroids, acetaminophen) although there is an overall lack of studies that are evaluating their efficacy.
• Joint supplements (chondroitin sulfate, glucosamine sulfate, omega-3-fatty-acid supplementation).
• Local intra-articular injections (in the joint) with different agents (corticosteroids, platelet-rich plasma, hyaluronic acid).
• Weight control. An overweight dog places additional force on joints causing more pronounced OA changes and can ultimately be more painful with limited mobility.
• Activity modification, which means that high-impact activities such as running or jumping should be limited as they can cause more inflammation and pain. These activities should be replaced with more controlled activity like leash walks. Low impact consistent activity is good to help build the muscles around the joints and will eventually promote joint stability.
• Surgical management can be indicated and in some instances the best treatment choice (cranial cruciate ligament rupture) and includes arthrodesis (fusion of joints), total joint replacement surgery (most commonly in hips, elbows), surgical stabilization of unstable joints (for stifle: suture-based or osteotomy-based techniques).

OA in pets is one of those conditions that is in a way, inevitable. Time will come that these pets will encounter this in their lifetime and ultimately, knowing how to manage and deal with OA will be vital. This is to, just like in humans; give these pets the best remaining years of their lives.

References:
1 www.acvs.org/small-animal/osteoarthritis-in-dogs
2 www.willows.uk.net/specialist-services/pet-health-information/orthopaedi...
3 Mele, Esteban. Epidemiology of Osteoarthritis. Veterinary Focus 2007; Vol 17 No3: 4-10.
4 www.msdvetmanual.com