Osteochondrosis is a condition that affects the formation of cartilage, which provides a protective gliding layer on the surface of the bones in a joint.
In puppies with osteochondrosis, the cartilage becomes thicker than normal and unable to receive a normal supply of nutrients from the joint fluid. This lack of critical nutrients as biomechanical stresses, cause the cartilage to become weaker and more susceptible to damage.
Because cartilage is the contact layer between the bones that form a joint, damaged cartilage causes joint pain, lameness, and progressive arthritis.
A form of the disease called osteochondritis dissecans (OCD) occurs when a weakened layer of cartilage forms a flap, which becomes elevated because of joint fluid building up between it and the underlying cartilage and bone. Mineralization, or hardening, can occur when the flap breaks off and floats around in the joint. This complication, called a joint mouse, can result in a "pebble-in-the-shoe" feeling of irritation for the dog, as well as intermittent or persistent lameness.
The cause of osteochondrosis is unknown, but because the disease is primarily seen in large and giant breed dogs, a genetic component is suspected. Other factors, such as a high-calorie diet and diets that promote rapid growth, are also thought to be significant.
This condition is usually seen in fast growing, large breed puppies, although it can be seen in some families of smaller dogs and mixed breeds. The most commonly affected breeds include the German Shepherd, Golden and Labrador Retriever, Rottweiler, Great Dane, Bernese Mountain dog, and Saint Bernard.
Overfeeding dogs a high protein/high calorie diet and over supplementing with vitamins and minerals – especially calcium – can worsen or accelerate the development of this condition in fast growing puppies.
Although the OCD flap may occur as a result of a minor trauma, the underlying osteochondrosis may be hereditary and passed on to offspring. If your pet is showing signs of pain, lameness, or swelling of the joints, you should have your pet evaluated by a qualified veterinarian.
Whenever your pet is showing signs of a health issue your first step is to contact your primary care veterinarian. If it is indicated that your pet may suffer from osteochondrosis or another serious condition, a veterinary specialist is available at an ExpertVet certified hospital.
Clinical Signs & Diagnosis
Osteochondrosis can affect any joint, but there are four joints in dogs that are commonly affected: the shoulder, the elbow, the stifle (knee), and the hock (ankle). Furthermore, the condition can be present in more than one joint even though the patient appears lame in only one leg. Thus, radiographs of other joints may be necessary.
Shoulder osteochondrosis, or shoulder OCD, results in a lesion developing on the head of the humerus, which is the bone in the upper front leg. Although this condition occurs while the dog is growing, some animals will not show signs of lameness until they have matured fully. By this time, more advanced disease may be present.
The majority of animals show lameness between the ages of 5 and 10 months. Lameness in the shoulder is usually one-sided and tends to improve with rest. However, the improvement is short-lived and pain recurs with exercise or with extension of the shoulder.
The amount of arthritis present depends on the size and duration of the lesion. In up to 75 percent of cases, both shoulders are affected. Because osteochondrosis is often bilateral, it is necessary to take x-rays of both shoulders to evaluate the extent of the disease.
Elbow osteochondrosis is one of three conditions that are grouped under the term elbow dysplasia and primarily occurs in large to giant breed dogs. With elbow osteochondrosis, the lesion is usually seen on the inside (medial side) of the humerus. Most dogs with elbow osteochondrosis experience lameness in the affected elbow at younger than 1 year of age.
As with the shoulder form of the disease, some dogs may not experience symptoms until they are much older and after the onset of significant arthritis. The lameness may be intermittent or persistent, tending to improve with rest and worsen with activity. Because it can be difficult to differentiate between elbow and shoulder osteochondrosis, x-rays of both joints may need to be taken. Even with x-rays, though, it can be difficult to detect a subtle lesion in the elbow. Advanced imaging or exploratory surgery may be needed in some cases before arrival at a definitive diagnosis.
Stifle osteochondrosis, which occurs in the knee joint, affects the same breeds and types of dogs that develop shoulder and elbow osteochondrosis, but it is much less common. Dogs with this disease usually show a slow onset of lameness that worsens with activity. The lesion will occur on the femur, the large bone in the thigh – and usually on the outer (lateral) part of the bone. The degree of arthritis depends on the size and duration of the lesion.
Tarsal or hock (ankle) osteochondrosis occurs in large dogs, most commonly the Labrador Retriever and Rottweiler. Hind-limb lameness and a straight-hocked stance are the most common signs. The joint will appear thick or swollen and will be painful on manipulation. With this form of the disease, arthritis tends to develop more rapidly and become more severe.
Your veterinarian may presume a diagnosis of osteochondrosis if your dog shows signs of disease and is a commonly affected breed. A definitive diagnosis requires analysis of x-rays and a thorough physical exam.