How Imaging Supports Diagnosis In Vet Neurology

Introduction

Elbow dysplasia is a common cause of forelimb lameness in dogs and therefore a common reason for referral. The term describes a group of developmental abnormalities affecting the elbow joint, rather than one single condition. Lameness (limping) and stiffness might start when the dog is young, or might not manifest until the dog is older and osteoarthritis develops.

Pathophysiology and Components of Disease

Elbow dysplasia encompasses several primary lesions (see figure 1). These include medial coronoid disease (which may involve fragmentation or fissuring of the medial coronoid process), osteochondritis dissecans of the medial humeral condyle, ununited anconeal process, and incongruity (how well the three bones of the elbow joint fit together). Medial coronoid disease is the most common form of elbow dysplasia and is seen in many breeds, though some, such as Labradors, develop it more frequently than others. The cause is not completely understood, and there might be several different pathways that result in damage to the medial coronoid process, such as incongruity, asynchronous growth between the radius and ulna, and breed-related conformational factors. Cartilage wear and subchondral bone changes develop over time, and these changes tend to progress even where the initial lesion is addressed. As a result, osteoarthritis is an expected outcome to some degree.

Osteochondritis dissecans (OCD) is a disease whereby the part of the cartilage at the end of the bone dies during development, resulting in a fragment of cartilage that breaks off from the bone. This condition is seen more commonly in Golden Retrievers than many other breeds.

In ununited anconeal process (UAP), a large “beak” of the ulna fails to unite with the main part of the ulna. It is an uncommon form of elbow dysplasia and is mostly seen in very large breed dogs, including German Shepherds.

Incongruity is thought to play a role in elbow dysplasia. It is obvious on diagnostic imaging in some dogs, and some breeds, such as Bernese Mountain Dogs, are predisposed to this form. In other dogs, it might not be as obvious or might be “dynamic” (only present when the elbow is in a certain position or loaded in a certain way).

Signalment and Clinical Presentation

Dogs are often presented between 5 and 12 months of age, although some are not assessed until later when osteoarthritic change becomes more apparent. Labrador Retrievers, Golden Retrievers, German Shepherd Dogs, Rottweilers, and Bernese Mountain Dogs are commonly affected. Lameness is frequently intermittent and may be described as “stiffness” after rest, or reduced willingness to exercise. Bilateral disease is common, which can make the lameness/limp less obvious. On examination, discomfort on elbow manipulation is typical. Reduced range of motion and joint effusion may be present. Muscle loss over the shoulder and upper forelimb can be seen in more chronic cases. External rotation of the paw is also sometimes seen.

Diagnostic Approach

Radiography can be a useful starting point but has recognised limitations. Secondary changes such as osteophyte formation, particularly on the anconeal process, and increased opacity within the ulnar trochlear notch may be visible. However, primary lesions, especially those affecting the medial coronoid process, are often not clearly identified on standard views. Radiography is generally most useful in older dogs, where the vet is looking for signs of osteoarthritis. It is also quite sensitive in identifying UAP where this is suspected. Computed tomography (CT) is often used in referral practice and allows a more detailed assessment of the medial compartment and joint congruity. It is more sensitive for detecting fragmentation, fissuring, and subchondral bone change than x-ray. Imaging both elbows is generally recommended. Arthroscopy is also an important tool, particularly where imaging findings are inconclusive or where intervention is planned. It allows direct assessment of cartilage integrity and identification of lesions that might not be visible on CT. It also allows concurrent therapeutic intervention where necessary.

Treatment Considerations

Management depends on the nature of the lesion, the degree of osteoarthritic change, and the clinical signs.

Surgical Options

Arthroscopic treatment is commonly performed for medial coronoid disease and OCD lesions. This may involve removal of fragmented cartilage and bone, debridement of abnormal cartilage, and treatment of exposed subchondral bone. Where joint incongruity is considered significant, procedures such as proximal ulnar osteotomy may be discussed. The aim with these is to reduce abnormal loading within the medial compartment. Outcomes can be variable, and case selection is important. Ununited anconeal process is often managed surgically, either through fixation and ulnar osteotomy, or fragment removal, depending on the age of the dog and the condition of the fragment.

Medical Management

Medical management is often required alongside surgical treatment and may be the primary approach in some cases. Maintaining an appropriate body weight is one of the more important factors in long-term management. Exercise is usually adjusted rather than restricted entirely, with an emphasis on consistent, controlled activity. Non-steroidal anti-inflammatory drugs are commonly used for pain-relief. Additional medications may be considered depending on the individual case. Physiotherapy can support muscle preservation and joint function.

Prognosis and Long-Term Outlook

The long-term outlook depends on a variety of factors. Factors inside the joint that are important include the extent and depth of cartilage and bone lesions, and the degree of incongruity. The most important patient factor that impacts the outcome is body condition, and maintaining a lean bodyweight is very important.

Progression of degenerative joint disease is common, even with appropriate intervention. Many dogs achieve a good level of function and remain comfortable with ongoing management. It is helpful for owners to understand that this is usually a chronic condition, and expectations should be adjusted accordingly.

Final Thoughts

Elbow dysplasia is a complex condition with a range of presentations and outcomes. Diagnosis often requires more than one modality, and management is rarely limited to a single intervention.

Referral is worth considering where lameness persists beyond 4-6 weeks, if the diagnosis is not confirmed, and where surgical options are being explored. Outcomes can be optimised when management is tailored to the individual patient and their circumstances.

Given the complexity of the condition and the varying pathologies involved, case-by-case assessment against a backdrop of specialist, evidence-based knowledge is likely to give the best long-term outcomes.

Elbow Dysplasia in Dogs