Q I have a 7-month-old Labrador retriever puppy, named Drake, who recently developed a limp in one of her hind legs. She had a swollen ankle joint. We did not see her injure the leg at any time. Sometimes she seems normal on the leg, but if she is very active, she is stiff, and limps on the leg afterwards. Our veterinarian sent an X-ray off to be read, and the radiologist diagnosed the problem as osteochondritis dissecans. Our vet said it was something she was born with, but was not sure what we should do about it. What would you advise?
A: Osteochondritis dissecans or OCD, is a developmental joint disease that primarily affects large-breed dogs, and is most commonly found in the shoulder, the ankle, elbow, and the knee. They are not technically “born with” this condition, but rather have a the genetic predisposition to it. External factors, mainly diet, can have a significant influence upon it’s development.
OCD happens because of a defect in the development of cartilage. Cartilage is a unique tissue type in that it has no blood supply. Cartilage gets all of its nutrition from the joint fluid. That is why regular activity is so important to keep our joints healthy. Moving and loading your joints circulates joint fluid, and actually feeds the cartilage by forcing the fluid into the cells. Because the joint fluid cannot penetrate too deeply, the cartilage at the ends of our bones is thin. That way the fluid can reach all of the cells.
As bone grows, part of that growth comes from the cartilage layer. As the cartilage layer grows, it cannot get too thick, otherwise the deeper layers will be too far from the joint fluid. So when a certain thickness is reached, the deep portion turns into bone. Thus the bone grows and the cartilage remains healthy. But, in dogs with OCD, the cartilage fails to convert to bone, and the deeper layer dies. This causes the cartilage to separate from the bone, leaving a painful flap of cartilage, and a defect where the bone should have formed.
The defect in the cartilage and bone leaves these joints unstable and lacking part of the normally smooth cartilage surface. The free flap of cartilage is also a source of pain. Over time, all of these factors will lead to joint degeneration and arthritis.
Treatment recommendations and prognosis depend largely upon which joint is affected. Surgery is a commonly recommended treatment regardless of location, but studies suggest that its long-term benefit in any joint other than the shoulder, may not be that much better than medical management. Shoulder OCD has a predictably good response to surgery, and this benefit seems to be long lasting. However in other sites, including the ankle joint, the effect of surgery may be short lived, owing to the removal of painful cartilage flaps.
Despite surgical intervention, the joints remain incongruent and defects in the bone and cartilage persist. Inevitably all of these joints will ultimately develop some degree of arthritis. Is it less arthritis than without surgery? Well, at least for the knees, ankles and elbows, the studies are mixed. When the shoulder is affected, the response to surgery is a different story. Not only do they resume normal function sooner than the other joints, but they generally retain normal function for life.
In my experience, regardless of location, the younger the dog is at the time of surgery, the better. These dogs seem to enjoy greater pain relief and earlier return to function. They all seem to feel, and function, better after surgery, but the duration of this effect in joints other than the shoulder, remains unclear.
Rapid growth in a large-breed dog is the single greatest risk factor for OCD, other than genetics. Its notable that the two species most commonly afflicted with OCD are the pig and the chicken. Both of these species experience explosive growth in the short time between hatching or birth and slaughter. Large-breed dogs likewise experience rapid growth, and this is frequently fueled by diets formulated for puppies. The single best prevention of OCD is proper feeding.
If your puppy is an at-risk breed, it should be fed a diet formulated for large-breed dogs, intended to slow their growth. Also effective is feeding your puppy adult dog food immediately after weaning. Don’t worry. They will reach their genetically determined size as long as they are provided a balanced diet. But a lower energy diet will slow things down, allowing a more coordinated growth. As important as the content of the food is making sure to feed the appropriate amount of food. This step not only reduces the chance of developing OCD, but of virtually every other developmental joint condition, including hip dysplasia.
As for Drake, since he is young, and the onset of the condition was described as recent, surgery would likely alleviate pain and improve function for the near or intermediate term, meaning a couple of years, maybe longer. Since this procedure is minimally invasive, and well-tolerated, I would say that the expected benefits favor a surgical recommendation. But maintain realistic expectations of the outcome. Research suggests that by the age of 5, his function would be no better than if he was only treated with supplements and medications.