Joint Dysplasia in Dogs: Causes and Signs

Approach to Joint Dysplasia (Elbow and Hip) in Dogs

• Joint dysplasia is a developmental disease affecting the coxofemoral (hip) or radio-ulnar (elbow) joints in dogs.
• The cause of dysplasia is unknown, but it involves a complex interplay of genetic and environmental factors, including exercise, body mass, and growth rate.
• Hip dysplasia is characterized by laxity and inadequate coverage of the femoral head by the acetabulum.

Etiopathology

• Hip dysplasia is a genetic disease with a complex inheritance pattern.
• Environmental factors like exercise, body mass, and growth rate influence the development.
• Laxity in the joint can lead to subluxation, followed by microfractures, cartilage tearing, synovitis, and ultimately pain.

Presentation and Clinical Signs

• In young dogs, signs include exercise intolerance, reluctance to climb stairs/jump, muscular atrophy, bunny hopping, short gait, and a narrow stance.
• Older dogs with degenerative joint disease experience reduced activity levels and behavioral changes associated with pain.
• Shoulder muscle hypertrophy might occur due to cranial weight shift.

Clinical Examination

• Ortolani test to examine hip for laxity (animal placed in lateral recumbency).
• Dorsal pressure during hip adduction; subluxation and clunk detected are positive.
• Less commonly positive in mature dogs due to acetabulum shallowness and joint capsule fibrosis.

Radiology/Diagnosis

• Lateral and extended ventrodorsally views for radiographs to avoid artefacts, especially in dorsoventral views.
• Femurs and cassette need to be parallel with patellas centering on femoral condyles.
• Assessing joint laxity: Measuring Norberg angle (>105 degrees is normal) and %femoral head coverage (>50% is normal).
• Signs of remodelling include blunting of the acetabular rim, flattening of the femoral head, subluxation, and thickening of the femoral head and deposition of osteophytes often at the attachment of the joint capsule.

Medical Treatment

• Conservative treatment in both immature and mature animals involves lean body weight, exercise management (lead walks, low-impact exercise, hydrotherapy), physiotherapy, analgesia, and nutritional supplementation.

Surgical Treatment Options

• Surgical treatment options for skeletally immature dogs include juvenile pelvic symphosiodesis (JPS), triple pelvic osteotomy, and femoral head and neck osteotomy.
• For skeletally mature animals, options are femoral head and neck excision and total hip arthroplasty.

Elbow Dysplasia

• Elbow dysplasia encompasses various developmental diseases with a genetic and environmental component resulting in degenerative joint disease (DJD).
• Key types include medial coronoid process disease (MCPD), osteochondrosis of the medial part of the humeral condyle (OCD), ununited anconeal process (UAP), radial-ulnar incongruency, and incomplete ossification of the humeral condyle (IOHC).

Anatomy

• Detailed anatomy of the canine elbow joint with labeled bones and ligaments is presented.

MCPD

• Cartilage erosions on the medial aspect of the canine elbow joint.
• Presentation includes unilateral or bilateral lameness, abnormal gait(stiffened/stilted), worsening after exercise and a period of rest.
• Clinical examination revealed pain on full elbow extension, pain on flexion/extension of the elbow, and lateral rotation of the foot. Possible effusion, thickened joint(s), decreased range of motion and crepitus are observed.

Osteochondrosis Dissecans of the Medial Humeral Condyle

• The cartilage underneath the bone in the elbow joint dies due to lack of blood flow.
• The bone and cartilage may break off, causing pain.
• Presentation includes lameness with stiffness and a stilted gait, worsening after exercise and immediate resting. Typically in young dogs (5–8 months old), in breeds like retrievers and Rottweilers, and in large/giant breeds.
• Clinical examination includes joint swelling, varus of the elbow and valgus of carpi, pain on deep palpation over the medial collateral ligament, and crepitus in older patients.

Ununited Anconeal Process (UAP)

• Failure of ossification to fuse with the olecranon at 5 months of age or less.
• Etiology unknown, possible link to radioulnar incongruity.
• Dogs with UAP often show intermittent/subtle or continuous/severe lameness, and presentation typically occurs in young dogs (5–8 months old) of breeds like German Shepherds, Saint Bernards, Basset Hounds (mostly males).
• Clinical examination reveals lameness in abducted position, varying degree of external rotation of the manus, elbow effusion, and pain during palpation, particularly on extension.

Radial-Ulnar Incongruency

• Malalignment of articular surfaces leading to uneven force distribution.
• The condition results from congenital factors, trauma, and chondrodystrophic breeds predisposition.
• It results in a presentation of lameness and stiffness, with worse symptoms after exercise or periods of rest, in predominantly large breeds and breeds prone to chondrodystrophy.

Incomplete Ossification of the Humeral Condyle (IOHC)

• Failure of bone union between the medial and lateral portions of the humeral condyle.
• Etiology unknown; occurs in young to middle-aged adult small to medium breeds.
• Dogs often present with weight-bearing lameness that worsens after exercise or rest (monolateral or bilateral).
• Clinical signs include pain on elbow manipulation and a stilted/stiff gait.

Diagnosis/Radiology

• Radiographs (orthogonal views, cranial-caudal projection), CT scans, and arthroscopy are considered for diagnosis.

Prevention

• Health testing and screening for hip and elbow dysplasia allows owners and breeders to only breed healthy dogs. Early identification is key and is often accomplished with radiographic or other imaging assessments.

Additional Information

• Surgical treatments do not prevent the progression of degenerative joint disease (DJD).
• Dogs with elbow arthritis may still function as pets but not as competitive, sporting dogs.