what causes arthritis?
Arthritis is caused either by abnormal forces being placed through normal joints, or normal forces being placed through abnormal joints-or possibly a combination of both. Although there could be a number of reasons why a dog develops arthritis, the most prevalent cause is developmental joint disease.
Developmental joint disease develops as the dog grows from a puppy into an adult, which highlights that many of the dogs presenting with arthritis later in life may have been contending with joint pain for much longer than has been noted. With 50% of dogs being diagnosed as arthritic between the ages of 8 and 13 years of age, and the disease detected at this stage being described as significantly progressed, it is likely that in many cases we are not identifying the early signs of this disease.
On a slightly happier note, being aware that developmental joint disease as a leading cause of arthritis means we are better able to identify the disease earlier, and take action, which translates into improved long-term results.
Arthritis can affect dogs of any age, from very young to old, and susceptibility is related to genetics and/or acquired factors such as obesity, joint trauma or infection, musculoskeletal injury or a combination of any of these factors.
Joints should be a perfect fit. If a dog’s joints do not form perfectly, abnormal movement patterns, which the joint was not designed to sustain, are likely. Normal mechanical forces applied daily to the abnormal joint may then lead to early onset of arthritis. Developmental diseases such as hip dysplasia, elbow dysplasia and patellar luxation are common underlying causes of hip, elbow and stifle arthritis respectively. These conditions are believed primarily genetic in origin, although they can be heavily influenced by environmental factors such as obesity.
There are no simple genetic screening tests that can be performed to identify dogs at risk, however certain breeds are more commonly affected. To learn about breed predispositions head to the Orthopaedic Foundation for Animals and Vet Lessons.
To reduce the prevalence of the genetically driven developmental joint diseases that lead to arthritis, the Kennel Club and British Veterinary Association (BVA) have schemes in place to survey predisposed breeds and allow breeders to make informed decisions regarding the suitability of sires and dams for breeding.
The schemes involve taking carefully positioned radiographs of dogs when they are near skeletal maturity to ensure they have “good” joints. Through considering their joint score and those of their parents and line, an informed decision can be made regarding the likelihood that a pairing will produce puppies who also have “good” joints.
When looking to purchase a puppy from a predisposed breed, it is recommended that you ask for the hip or elbow scores of the parents to try and ensure your puppy will have less risk of poorly formed joints, even though these may not become apparent until your puppy is older.
Of course, a puppy’s upbringing is also very important - injuries sustained as a puppy, inappropriate exercise at a young age, poor balance of nutrition and obesity could all increase the risk of hip or elbow dysplasia prone puppies manifesting those diseases.
Obesity has a huge influence on the development, progression and severity of the clinical signs of arthritis. The increased weight of the excess fat causes abnormal mechanical loads and forces to be placed through a dog's joints on a daily basis. These excessive forces will increase significantly when the dog is doing more taxing activities such as running or jumping.
Fatty tissue, known as adipose tissue, is not just a reserve of potential energy. It is also a source of inflammatory mediators which aggravate and progress inflammatory diseases like arthritis. This concept was clearly shown in humans, where overweight people were more likely to suffer arthritis in their hands which are non weight bearing. This indicates that mechanical weight bearing forces are not the only cause of arthritis.
Fat is also known to infiltrate structures like ligaments and tendons which could influence their ability to carry load effectively. These structures are essential for joint stability, which in turn is essential to avoid abnormal forces, which can lead to arthritis.
It is vitally important to keep your dog at a healthy body weight throughout their life, so a good balance of nutrition suitable to their breed, age and lifestyle needs to be chosen. It is likely that an overweight adult dog was an overweight puppy, so paying attention to puppy growth rate is important. Puppy growth charts are available to guide your dog’s development.
Using breed averages to work out your dog’s ideal body weight can be very misleading. A sensible alternative is to monitor their body condition score. For more advice head over to our weight management page and sign up to our FREE email series offering tips on how to achieve an optimum body weight in your dog.
An injury to a joint, such as cruciate ligament rupture, will predispose a dog to developing arthritis in that joint. This can happen regardless of whether the dog has surgery for that condition or not.
Similarly, conditions such septic arthritis or immune mediated polyarthritis will cause damage to the joints that is likely to lead to arthritis.
It is important if your dog has suffered from any of these conditions to do everything you can to reduce any further risk factors for arthritis development (e.g. obesity, inappropriate repetitive high impact activities). These dogs should be monitored for indications of ongoing joint pain, so that action can be taken to minimise the progression of the disease, and keep them as comfortable as possible for as long as possible.
Another consideration is to minimise the risks of joint trauma. CAM believes we can reduce the prevalence of arthritis in dogs through considering the suitability of a dog's lifestyle and minimising risks of injury that may come with it.
Ensuring your dog has regular reassessments with your vet is an excellent way to identify potential deterioration or arthritic changes early.