What Is Osteochondrosis?
Osteochondrosis (OC) is a developmental orthopaedic disease in which the normal process of cartilage converting to bone — a process called endochondral ossification — is disrupted. In a healthy, growing dog, cartilage at the joint surface gradually transforms into bone in a controlled and orderly fashion. In osteochondrosis, this conversion fails in localised areas, causing the cartilage to become abnormally thick. The thickened cartilage is poorly supplied with nutrients, making it vulnerable to damage under normal loading.
When the weakened cartilage develops a crack and a flap of cartilage partially or fully separates from the underlying bone, the condition is called osteochondrosis dissecans (OCD). A detached cartilage fragment — sometimes referred to as a joint mouse — floats freely within the joint cavity, causing significant pain and ongoing damage to the joint surface. OCD represents a more advanced and clinically significant stage of the same underlying process.
Which Joints Are Affected?
Osteochondrosis can affect several joints, and the shoulder is the most commonly involved site in dogs. The lesion typically develops on the caudal (rear) aspect of the humeral head — the ball of the shoulder joint. The elbow is the second most commonly affected joint; here, OCD forms part of the broader syndrome known as elbow dysplasia, with the lesion occurring on the medial humeral condyle. The stifle (knee) and hock (tarsus) are also affected, though less frequently. In order of clinical frequency, shoulder OCD is the predominant presentation, followed by elbow, stifle, and hock.
Causes and Risk Factors
Osteochondrosis is a multifactorial disease. Genetic predisposition plays a significant role, which explains why certain breeds are markedly over-represented. The condition arises during the rapid growth phase of large and giant breed dogs, when the demands on developing cartilage are greatest.
Dietary factors also contribute meaningfully. Overfeeding — specifically providing excess calories that accelerate growth rate — is a well-established risk factor. Calcium supplementation in growing puppies is particularly problematic; excessive dietary calcium interferes with normal bone remodelling and is strongly associated with developmental orthopaedic diseases including osteochondrosis. Owners of large breed puppies should avoid adding calcium supplements unless directed by a veterinary surgeon. Trauma to developing cartilage may also trigger or worsen lesion development.
Breeds Most Commonly Affected
Breeds with a known predisposition to osteochondrosis include Border Collies, Labrador Retrievers, Golden Retrievers, Rottweilers, Great Danes, Bernese Mountain Dogs and Irish Wolfhounds. The condition is almost exclusively seen in large and giant breeds during their growth phase, though it can theoretically occur in any breed. Males appear to be affected more commonly than females in some studies.
Signs and Clinical Presentation
The typical presentation is a young dog — usually between four and twelve months of age — with forelimb lameness that may be subtle at first and worsens with exercise. In shoulder OCD, the dog often resents extension of the shoulder joint during examination, and a veterinary surgeon will detect pain and sometimes swelling (effusion) in the affected joint. Muscle atrophy around the shoulder may become apparent over time as the dog guards the limb.
In elbow OCD, the signs are similar but focused on the forelimb lower down — the dog may show an outward rotation of the paw, pain on elbow manipulation, and joint swelling. Stifle and hock OCD typically present as hindlimb lameness in the same age group.
Diagnosis
Diagnosis begins with a thorough orthopaedic and neurological examination. Radiographs are the first-line imaging tool and may reveal a flattening or defect of the articular surface, or a visible calcified cartilage flap in established cases. However, radiographs can miss early or subtle lesions. Computed tomography (CT) scanning provides superior detail of the bony changes and is more sensitive than radiography for detecting lesions, particularly in the elbow.
Arthroscopy — minimally invasive examination of the joint using a small camera inserted through a tiny incision — is considered the gold standard for both diagnosing and treating osteochondrosis. It allows the surgeon to directly visualise the cartilage surface, assess the extent of the lesion, and intervene surgically in the same procedure.
Treatment Options
Conservative Management
Strict cage rest for four to eight weeks may be appropriate in mild cases where the cartilage has not yet detached to form a free flap. Some early lesions heal with rest and restricted activity. However, conservative management carries the risk of ongoing joint damage if the cartilage subsequently fails and detaches, and it is generally not recommended once a cartilage flap has separated. The decision to manage conservatively or proceed to surgery should be made in consultation with a veterinary surgeon familiar with the specific lesion type and joint involved.
Surgical Treatment
Arthroscopic surgery is the preferred treatment for osteochondrosis dissecans once a flap has developed. The procedure involves removal of the cartilage flap, followed by curettage — gentle scraping — of the underlying subchondral bone to remove abnormal tissue and stimulate the formation of fibrocartilage to fill the defect. Arthroscopy causes significantly less surgical trauma than open joint surgery and allows faster recovery. Best outcomes are achieved when surgery is performed before substantial osteoarthritis has developed in the joint.
Prognosis
The prognosis varies according to the joint affected and the severity of the lesion at the time of treatment. Shoulder OCD generally carries a good to excellent prognosis following arthroscopic surgery, with most dogs returning to full activity. Elbow OCD, as part of the complex elbow dysplasia syndrome, carries a more guarded prognosis — some degree of osteoarthritis is usually already present and will continue to progress. Stifle and hock OCD have variable outcomes depending on lesion size and joint involvement.
Prevention in Large Breed Puppies
Whilst genetic predisposition cannot be controlled, dietary management offers a meaningful opportunity to reduce risk. Large and giant breed puppies should be fed a diet specifically formulated for large breed growth — these diets are designed to provide controlled calorie and calcium levels that support steady, healthy development without accelerating growth rate. Avoid feeding additional calcium supplements unless they have been specifically prescribed by a veterinary surgeon. If a puppy begins to show any sign of lameness during the growth phase, prompt veterinary assessment is important, as early identification gives the best chance of a good outcome.