Osteoarthritis is one of the most commonly seen chronic degenerative diseases in geriatric dogs. Even though some breeds are more prone to develop this condition, several authors confirm that almost 20% of all senior dogs suffer from it. Other known names for this frequent disease are osteoarthrosis, degenerative arthritis, and hypertrophic arthritis, among others.
In a few words, the disease consists in a progressive loss of cartilage, tissue that makes up for most of the joint components. It can also present itself with bone proliferation and changes in the synovial fluid and membrane. It can be classified into two categories:
- Primary Osteoarthritis. Also called idiopathic osteoarthritis, this type of OA is rare in dogs and has an unknown cause. Authors believe it might be linked to genetics, although this has not been proven yet.
- Secondary Osteoarthritis. It is a complication, or a condition derived from an underlying cause. Genetic disorders generating abnormal cartilage formation, infectious diseases such as Lyme or ehrlichiosis, hip dysplasia, ligament ruptures, patellar subluxation, immune-mediated polyarthritis, obesity, trauma, etc.
Regardless of its origin, OA is a very painful disease for dogs, and can lead to several complications. The synovial fluid and membrane, as well as the actual bones involved in the articulation can become affected. It is important to highlight that the general definition of OA holds a “non-inflammatory disease” label on it, but it DOES progress to synovial inflammation. This chronic inflammation and damage may cause a reaction in the body of generating bone structures around the joint to avoid movement and pain, issue that eventually will also leave place to muscular atrophy and tendon weakness. Also, synovial edema or effusion is commonly seen, as the permeability of the capillary vessels is increased due to the persistent inflammatory stimuli and the serum proteins begin to leak out of the vessels.
Anamnesis and Clinical Signs
The OA patient will come in for consult for lameness, stiff walking, exercise intolerance, evident joint edema, pain, and in such case, other symptoms corresponding to an underlying cause (fever, weight loss, lethargy, anorexia, etc.). In other cases, the patient may not be yet presenting any signs of OA, and the finding might be incidental (generally joint crackling) during a clinical examination regarding a different symptomatology. Clinically, muscle atrophy can be seen in chronic cases, unstable weight relying, crepitus and capsular fibrosis.
A general clinical exploration should always be performed, in order to rule out underlying causes of the arthropathy and confirming OA.
The most valuable tool for the diagnosis of arthropathies is radiology. Although, most of the times, the radiographic changes will be seen once the disease has progressed; early stages of OA do not show significant findings. The reason behind this is that cartilage cannot be examined through radiology, only bone changes, so chronic cases become evident by observation of osteophytes around margins and attachment points. The only way to assess joint integrity is measuring the joint width (initially widened because of the inflammation, but eventually thinned because of tissue loss), which is a challenge in dogs, since it has to be done while the patient relies its weight on the affected limb. Other radiographic findings may be increased synovial fluid opacity and displacement of the joint capsule.
Blood count may or may not be altered. If so, moderate neutrophilia may be seen, but more bloodwork might be necessary to check for Lyme, ehrlichiosis, and other infectious polyarthritis-generating diseases. Synovial fluid should also be tested to evaluate the actual cellular changes inside the joint. OA generally shows synovial fluid dilution, increased volume and mild inflammatory cytology. Arthroscopy can help detect OA at earlier stages, which would be useful to start treatment before symptoms manifest, and thus delaying the appearance of the disease.
Being a chronic degenerative disease, OA does not have a cure per se. Treatment for OA mostly consists in:
- Pain Management. Quality of life is the number one concern in OA patients. NSAID analgesics are the most commonly used, being meloxicam and carprofen the more frequently administered. The pros of pharmacological treatment are that pain relief is almost immediate and can be maintained for a relatively long time (especially with carprofen for long-term treatment). The main con is that most NSAIDs are nephrotoxic, which is especially dangerous in geriatric dogs; this type of medication must be applied carefully, while monitoring renal function every 2-6 months. Also, NSAIDs irritate the gastrointestinal mucosa, so they must not be used in patients with history of GI tract diseases.
- Weight Control. Keeping a healthy body condition is extremely important, since overweight and obesity can be primary causes or worsening factors for degenerative joint disease. This can be achieved by providing premium quality food for normal weighing dogs, or special diets with calorie regulation goals for obese dogs.
- Nutraceuticals. Glucosamine and Chondroitin sulfate are commonly added to treatment, since they apparently improve mobility by helping restore the lubrication of the joints. These effects are not entirely proved, so treatment should not be based solely on nutraceutical products.
- Physiotherapy. This practice has gained a lot of popularity, showing good results in helping restore mobility in OA patients. Hydrotherapy involves a series of limb movements (flexion, extension, etc.) under the water; local hypothermia for acute processes and then local hyperthermia for muscle relaxation and pain relief; motion exercises and TENS therapy help with muscle atrophy.
- Acupuncture. Generally used in patients that show to be refractory to medication, or are not candidate to NSAID therapy because of renal, gastrointestinal or liver damage, acupuncture consists in the insertion of small needles into specific, highly enervated body parts, in order to minimize pain and inflammation.
- Surgery. Very rarely practiced, but can be an option for young patients in which the main problem is the appearance of removable osteophytes. More often done when the underlying cause can be corrected, like some ligament ruptures. Other techniques such as arthroplasty (femoral head removal) and arthrodesis are also indicated on very specific cases.
PRP: Better Pain Management
As previously established, and since there is no definitive cure, the main objective of the therapy for the OA patient is an adequate pain management, and since the commonly used medications have a lot of secondary effects and contraindications, other alternatives have been explored, both in human and veterinary medicine. These alternatives include, among others, intra-articular injections of many different pharmacological agents, such as corticosteroids and hyaluronic acid, showing a more sustained analgesic effect.
First used in the equine veterinary practice and now in canine medicine, autologous Platelet-Rich Plasma intra-articular injections have proved to be even more long-lasting than any other drug administered this way. The growth factors inside the alpha granules of the platelets have many different functions, among which regenerative and anti-inflammatory ones stand out. Different studies have found that PRP inhibits certain cytokine release, therefore inhibiting the inflammatory response and promoting tissue regeneration. This effect is incredibly evident in cartilage tissue, since PRP stimulates collagen and elastin, generating, indeed, brand new functional cartilage where there was only destroyed tissue.
A study made by Marie A. Fahie et al. (2013), which was published in the Journal of American Veterinary Medical Association, compared the effect of PRP intra-articular injections against saline solution intra-articular injections in dogs with OA. The lameness and pain scores were 55% and 53% improved with a single PRP injection after 12 weeks. This shows that any patient, no matter its age, kidney function, liver function, GI tract history, breed, size, or any other variable you might think of, is a candidate for a PRP intra-articular injection, which will maintain a pain-free status for 3 months.
More studies and clinical essays must be done to standardize these numbers and timings, but one thing is for sure: PRP therapy, aside from being affordable, easy and quick, is already the present and future of veterinary orthopedics.
If you want to know more about the application of PRP intra-articular injections, please check out our GET STARTED Section, where you’ll find the Application segment with everything you need to know in order to start using this amazing technique!