Inherited and Growth Conditions in Dogs

Inherited conditions come directly from the parents, may be present at birth or develop later in life. Some conditions may also be influenced by the rapid growth of puppies, nutrition issues, or environmental factors. Common conditions in these categories are hip and elbow dysplasia which includes OCD, FCP, or UAP.

Hip dysplasia is the abnormal development of the hip joint, usually occurs on both sides, and is more prevalent in medium and large breed dogs. It is due to a laxity in the joint which leads to malformation of the femoral head (the top of the femur or thigh bone) and the acetabulum (the concave surface of the pelvis that the femoral head is normally surrounded by) and inadequate coverage of the femoral head by the acetabulum. There are many factors that may contribute to the cause of hip dysplasia. These include, rapid growth rate, diet, environmental factors, and/or genetic susceptibility. The hip joints are normal at birth but the muscles fail to develop at the same rate as the bone and this results in joint instability between 4-12 months of age. This causes the femoral head to pull away from the acetabulum due to the laxity and a series of changes start to occur such as a shallow acetabulum, flattening of the femoral head from wear and eventually the development of osteoarthritis. If the muscles aren’t strong enough, femoral head subluxation occurs (the femoral head does not stay within the acetabulum).

Signs of hip dysplasia in younger dogs:

• Reduced activity and soreness of the hind limbs

• Difficulty rising and decreased willingness to walk, run, jump, or climb stairs

• Poorly developed muscles of the pelvis and hind legs

• Short steps in the hind limbs, and/or “bunny hopping” while running (moving both hind limbs together)

• Positive Ortolani Sign: This is a test your veterinarian can perform that produces a click as the femoral head slips in and out of the acetabulum

• Radiographs usually show some sign of subluxation and the angle of the femoral neck (the portion of bone between the femoral head and the femur) may be increased

Older dogs with more chronic degenerative joint disease may present differently:

• Lameness (either unilateral or bilateral) after prolonged exercise

• Waddling gait

• Crepitus (crunching noise) with movement of the joint

• Decreased range of motion in the hind limb(s), especially hip extension (moving the leg behind them)

• Difficulty rising from lying down

• Atrophy of the hind limb muscles and gluteal weakness with hypertrophy of the shoulder muscles due to the forward weight shift and increased use of the front limbs to do the work of rising

• Radiographic changes of osteoarthritis may be seen

Treatment

It is important to know that many dogs may show radiographic signs of hip dysplasia, but little to no signs of pain. Conservative treatment approaches would include:

• Adjusting exercise to what the dog can do without signs of pain. This may mean limiting jumping or other strenuous exercise such as frisbee, fetch, running, or competition.

• Weight reduction in obese dogs and maintaining a lean body mass (4.5/9 on the Body Condition Score)

• Analgesics and anti-inflammatories

• Chondroprotective agents such as Adequan injections

• Supplements such as Omega 3s, glucosamine/chondroitin, tumeric, green lipped muscle, hyaluronic acid, undenatured Type II Collagen, egg shell membrane, boswellia extract or combinations of these.

In severe cases, surgery can be performed. There are many types of surgery depending on the severity of the disease and the age of the dog, which I will not go into here today.

Elbow Dysplasia

There are several developmental conditions that can cause elbow dysplasia. OCD, FCP, UAP, and incongruity of the bones are all considered to have genetic origins which lead to elbow dysplasia, but improper nutrition, trauma, and asynchronous growth of the radius and ulna may also contribute. These conditions are usually diagnosed via x-ray, but CT scan is more helpful in mild cases. All of these conditions lead to arthritis in the elbow.

Osteochondritis Dissecans (OCD)

OCD is a defect in bone growth and causes lesions in the cartilage. A flap of cartilage may become partially or fully detached and moves within the joint causing pain. It most commonly occurs in the shoulder or elbow, but can also occur in the knee or ankle as well. The cause has not been determined, but may be related to overnutrition, rapid growth, excess dietary calcium, ischemia, hormonal influences, or trauma and a genetic component is likely. Retrievers, Bernese Mountain Dogs, and Rottweilers between the ages of 5-8 months are most commonly affected by elbow OCD. OCD often presents as a front limb lameness or stiffness that is intensified by exercise and noticed after a rest period. There is often joint swelling on the outside of the elbow and muscle atrophy may be present if the dog has been lame for many weeks. There is pain on flexion and extension of the elbow and chronic cases may have swelling and thickening of the tissues as well as decreased range of motion and crepitus. Diagnosis is made with x-rays performed between 5-9 months of age and confirmed with arthroscopic surgery. Both elbows should be examined and FCP may be present in addition to the OCD (37% of the time). Treatment involves the surgical excision of cartilage flaps, removal of any loose cartilage in the joint, and smoothing out the area of the lesion . Good results are obtained if this surgery is performed before any degenerative joint disease has occurred, but there will need to be long term management of arthritis.

Fragmented Medial Coronoid Process (FCP) is most often bilateral and it is the most commonly diagnosed developmental issue of the elbow in young dogs. In older dogs, it is often called '“jump down syndrome” as it often occurs due to excessive and/or repetitive loading in high impact situations. There is strong evidence that shows a genetic component to this diagnosis and Labrador retrievers, Bernese Mountain Dogs, and Rottweilers are most affected. FCP is the fissure or complete separation of the medial coronoid process (an outcropping of bone) from the ulna (one of the two forearm bones). Signs of FCP are similar to that of OCD, but you may also see pain on flexion and extension of the elbow and outward rotation of the limb as well as pain with palpation of the inner elbow and swelling. In dogs older than 11 months, crepitus, decreased range of motion, and joint thickening may be present. Radiographs are important in diagnosing FCP. Although there are no specific indications of FCP on x-ray, there are signs that can indicate and help confirm this diagnosis. Treatment is surgery to remove the fragment. Prognosis is good if the FCP is removed before there are advanced degenerative changes, but again there will still need to be long term management of arthritis.

Ununited Anconeal Process (UAP) occurs when the anconeal process (a bony projection of the ulna) fails to fuse with olecranon (the point of the ulna) by 5 months of age. It occurs mostly in large breed dogs, especially German Shepherds, basset hounds, and St. Bernards. Instability or detachment leads to eventual osteoarthrosis of the elbow and can be bilateral. Signs of this condition are usually not apparent before 5-8 months of age and sometimes not for several years. The first sign is a slight limp with the lower limb and elbow slightly out to the side and elbow generally locked in extension. The dog will swing the leg out to the side rather than bend it during walking. The dog often sits and stands with the front limb rotated outward and the toes can seem widespread. There can be swelling and decreased range of motion in the elbow. Diagnosis is best made via radiographs and both elbows should be examined. Treatment is most often surgery to remove the anconeal process, although they may use a screw to fix the anconeal process, but this works best if performed early (5.5-6 months of age).

Elbow incongruity is when the bones of the arm (most commonly the radius and ulna, the bones of the forelimb) do not grow at the same rate. The cause is unknown, unless there is injury to the growth plate. Radiographs can clearly show this incongruity. Surgical intervention could involve either lengthening or shortening of one of the bones.

Long term management of elbow dysplasia should be sought as it eventually leads to osteoarthritis even if surgical intervention was performed. This should include multiple avenues of management including weight management, activity modification, chondroprotectants, pain management, Omega 3 fatty acid supplementation, therapeutic modalities (laser, shockwave, pulsed electromagnetic field therapy), therapeutic exercise, acupuncture, manual therapy, and intra-articular injections such as biological therapy, hyaluronic acid, or cortisone.

References:

Duerr, Felix. (2020). Canine Lameness, WILEY Blackwell

DeCamp, C.E., Johnston, S.A., Dejardin, L.M., Schaefer, S.L. (2016). Brinker, Piermattei, and Flo’s Handbook of Small Animal Orthopedics and Fracture Repair (5th edition), Elsevier

Millis, Darryl L. & Levine, David. (2014). Canine Rehabilitation and Physical Therapy (2nd edition), Elsevier

Zink, Chris & Van Dyke, Janet B. (2018). Canine Sports Medicine and Rehabilitation (2nd edition), WILEY Blackwell

Association for Pet Obesity Prevention (2025). Dog Body Condition Score (BCS) Chart & Assessment Guide, https://static1.squarespace.com/static/6425ec5d33eaaa634113b2d4/t/68c6bf3266812238c6965bc5/1757855538748/Body+Condition+Score+for+Dogs.pdf

Canine Arthritis Research and Education. Pet Parents Dashboard. Developmental Orthopedic Disease: What is Elbow Dysplasia. https://caninearthritis.org/article/dod-elbow-dysplasia/

Next week: Degenerative Myelopathy