Osteochondritis Dissecans (OCD)

C. Denise Wall, PhD

If you have been involved in border collies for very long, you have probably heard that OCD is a potential health problem for the breed. Therefore, the typical owner or breeder might have some basic questions concerning this condition. What is OCD? Is it inherited? How can you prevent it? What can you do about it if your dog already has it? These questions will be addressed in the following summary of the current literature.

What is OCD?

OCD is a condition that occurs in growing puppies of larger breeds, primarily between the ages of 4-9 months, but can occur as late as 12 months or older. It is most commonly seen in the shoulder joint but can be seen in stifles, elbows, hocks or other joints. In approximately one third of the cases of OCD, the disease is bilateral (in both joints). Occasionally, it is present in several different joints in the same individual. It is seen twice as often in males as in females.

OCD is thought to be caused by a problem in the growth rate of the joint cartilage relative to the underlying subchondral bone. The cartilage over the bone in the joint becomes thickened and the growth of the underlying bone is altered. Because the joint is an area of movement and stress, this thickened cartilage is at risk of being torn, especially in the areas most subjected to trauma, stress and movement, such as the caudal area of the shoulder joint. When repeated trauma causes a flap of cartilage to tear away from the underlying bone, the condition becomes OCD. Because of the tear, the joint fluid can come in direct contact with sensitive areas of the now-exposed underlying bone and can cause pain. Lameness will usually be present in the dog at this time. If the cartilage flap remains attached, it will not re-attach and heal back into its original position. If the cartilage flap tears completely loose from the adjoining cartilage, it becomes a loose body in the joint called a "joint mouse". Once the flap has detached, the torn area where the flap originated usually heals when the lesion is filled in with fibrocartilage, a type of "scar" cartilage. Joint mice may float around in the joint, eventually being broken down and absorbed, or they may be nourished by the joint fluid and grow to a larger size than the original loose cartilage body. Possible complications arise when joint mice attach themselves to other areas in the joint or become entrapped it the bicipital tendon sheath, causing irritation, obstruction of movement and pain. The breakdown of cartilage from these various processes may cause inflammation, pain and the eventual development of secondary osteoarthritis in the affected joint.

Is it inherited?

OCD is a considered to be a common disease in large and rapidly growing breeds of dogs, with most affected breeds averaging over 60 lbs. However, some medium breeds, such as the Brittany spaniel, bull terrier, greyhound and border collie, also have a high incidence of this disease. Although the factors that cause OCD are not completely resolved, direct factors considered to be involved in the development of OCD are rapid growth and trauma to the joint. Indirect factors affecting rapid growth include nutrition, hormones, and genetic predisposition to rapid growth and large size. Indirect influences that may lead to increased trauma to the joint include conformation and behavior, which are also influenced by heredity. Therefore, the genetic link for most types of OCD is considered to be indirect, that is, an inherited tendency. Certain sites for OCD lesions, such as the elbow, appear to have a greater direct genetic contribution and a higher heritability than other sites, such as the shoulder. The most important contributing factor in OCD of the shoulder, the most common site, is thought to be trauma.

Border collies have a higher incidence of OCD than might be expected for their size and the weight bearing stress on their joints. It would seem likely that behavioral characteristics common to border collies could contribute to the increased occurrence of OCD in this breed. The high energy levels, athletic ability, stamina and quick reflexes for fast turns and speed changes many border collies possess could predispose them to trauma and stress in joints that most other breeds of similar size would not commonly experience. The overall increased incidence in males for this disease is thought to be due to the increased growth spurt in the male around the susceptible time period for OCD development. As well, it is tempting to speculate that behavioral factors common to males might also be involved in this increased susceptibility.

How can it be prevented?

As in many other developmental skeletal problems, an imbalance of calories, protein and nutrients can increase the occurrence of OCD. In general, rapid weight gain in puppies at the critical time period between 4-9 months predisposes larger breed dogs to OCD. High intake of calcium and protein has been implicated in the development of this condition. Therefore, care must be taken in feeding young puppies special "growth formula" puppy foods or high protein diets. Puppies need extra calcium and protein but free choice or overfeeding of these diets can be harmful. It is of interest to note that some dog food manufacturers have recently responded to health concerns of dog breeders and owners by formulating puppy foods specifically for large breed dogs.

Since trauma is a contributing factor to the development of OCD, it would be reasonable to monitor exercise in puppies, especially between the ages of 4-9 months. Activities such as excessive running and roughhousing with people or other dogs should be avoided. In addition, puppies shouldn't engage in intense activities that encourage abrupt, fast turns, quick stops, or jumping, especially jumping from heights. Of course puppies need exercise and should be allowed to be reasonably active, but they should also be watched carefully so that they don't do too much or do things that might cause injury.

What can you do about it if your dog already has it?

OCD is diagnosed by the combination of radiographic evidence and clinical signs, such as lameness. The dog may demonstrate stiffness after rest, but typically the lameness worsens with exercise. Severity of clinical signs do not always correlate with radiographic evidence of disease. The OCD defect is usually detected on x-ray as an irregular appearing or flattened subchondral bone surface, sometimes appearing as a crater-like lesion on the surface of the joint. In severe cases, radiographic evidence of secondary osteoarthritic changes may also be observed. Cartilage flaps and joint mice do not normally show up well on x-ray. Therefore, a procedure called an arthrogram may be needed to visualize a loose cartilage body or a cartilage flap in the joint.

Given the course of the disease and the associated problems described earlier, it is probably not surprising that the treatment of choice for most cases of OCD is surgical removal of the cartilage flap or joint mice. Indeed, over 90% of dogs diagnosed with OCD of the shoulder have a successful recovery with surgery. Surgical approaches usually include exposing the entire joint for removal of the cartilage flap and any joint mice, as well as lightly scraping the surface of the defect to remove any remaining fragments of loose cartilage and to encourage healing. There have also been reports of successful outcomes using arthroscopic surgery, a procedure that has the advantage of being less invasive, less time consuming, and enabling a quicker return to function. Possible limitations of the arthroscopic procedure for OCD often make it an unlikely choice, however.

Conservative treatment (non surgical) is controversial for this condition. Some clinicians recommend encouraging exercise, in an effort to aid in removal of the cartilage flap so healing can occur. Conversely, some clinicians recommend rest and restricted activity, at least until the dog is seven months of age and the defect has matured. Regardless of the conservative approach used, a higher percentage of dogs go on to have permanent lameness and secondary joint changes associated with osteoarthritis when conservative treatment is used instead of a surgical approach.

A potentially promising advance in future treatment for OCD, both post surgically or in conservative treatment, is the use of polysulfated glycosaminoglycans such as the drug Adequan. Although it has been used successfully for many years in horses, this drug has only recently come into use in small animal medicine, where it is being used in dogs to treat degenerative joint diseases such as hip dysplasia. Adequan is currently only approved for use in horses and there are no controlled scientific studies of its effectiveness in treating OCD in dogs. However, it is thought to have joint healing and protecting properties that may prove to be beneficial in the treatment of OCD, as well as many other joint diseases in small animals.

References:

Fox, S. M.; Walker, A. M.: The etiopathogenesis of osteochondrosis. Veterinary Medicine 88(2):116-122;1993.

Fox, S.M, Walker, A.M.: OCD of the humeral head: Its diagnosis and treatment. Veterinary Medicine. 88(2):123-131;1993.

Guthrie, S., Pidduck, H.G.: Heritability of elbow osteochondritis within a closed population of dogs. J of Small Animal Pract. 31:93-96;1990.

Knecht, C.D., Van Sickle, D.C., Blevins, W.E., Avolt, M.D., Hughes, R.B., Cantwell, H.D.: Osteochondrosis of the shoulder and stifle in 3 or 5 Border Collies littermates. JAVMA. 170:58-60;1977.

LaHue, T.R., Brown, S.G., Roush, J.C., Ticer, J.T.: Entrapment of joint mice in the biciptal tendon sheath as a sequela to osteochondritis dissecans of the proximal humerous in dogs: A report of six cases. JAAHA. 24:99-105;1988.

Padgett, G.A., Mostosky, U.V., Probst, C.W., Thomas, M.W., Krecke, C.F.: The inheritance of osteochondrosis dessicans and fragmented coronoid process of the elbow joint in labrador retrievers. JAAHA. 31:327-330;1995.

Riser, W.H, Woodard, J.C., Bloomberg, M.S., Goring, R.L.: Shoulder lesions in the Greyhound with special reference to osteochondritis dissecans and chondrocalcinosis. JAAHA. 29:449-454;1993.

Rudd, R. G.; Whitehair, J. G.; Margolis, J. H.: Results of management of osteochondritis dissecans of the humeral head in dogs: 44 cases (1982 to 1987). JAAHA. 26 (2):173-178;1990.

Slater, M.R., Scarlett, J.M., Donoghue, S., Kaderly, R.E., Bonnett, B.N., Cockshutt, J., Erb, H.N.: Diet and exercise as potential risk factors for osteochondritis dissecans in dogs. Am J Vet Res. 53:2119-2124;1992.


Copyright 1997. All rights reserved by C. Denise Wall.