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Skeletal System Disorders - Osteochondritis Dessican (OCD)

The Diagnosis Is ... 
Osteochondritis Dissecan (OCD)


by Chris La Muraglia, Pat Randall, and Tracy Warncke. Technically reviewed by NCA member Jan Curtis, DVM.  

Description: OCD of the shoulder is one of the more common causes of forelimb (front-end) lameness in developing large dogs, including the Newfoundland. It is a disorder of developing cartilage in which ossification (the replacement of juvenile cartilage by bone) is delayed. The cartilage continues to thicken on the growth region on the surface of the humeral head. The thickening cartilage diminishes the delivery of nutrients to the deep layers and these cells may die. When this happens the dog has what is called "osteochondrosis," a condition that is usually without symptoms, will not be radiographically visible, and often heals spontaneously.

ocdimage
ocd2 Eventually the surface cartilage overlying the initial lesion may collapse, causing a lesion (or detached "flap" of cartilage) on the surface of the humeral head, a weight-bearing area. When a lesion on the surface is present, the dog has OCD or osteochondritis dessicans. This is the stage of the disease at which lameness appears and at which your veterinarian will usually be able to diagnose the problem upon physical exam or radiographically. Further, a piece of cartilage may break off of the surface becoming a "chip" or a joint mouse. Cracks in the surface cartilage, and in particular the joint mouse, cause inflammation and often a great deal of pain in the shoulder. 

Though OCD is most common in the shoulder, similar disease processes may occur in the elbow, stifle, or even hip. Another syndrome, retained ulnar cartilaginous core, is also an OCD-like lesion occurring at the distal ulna. 


With this etiology, it is easy to see why, even though thought to have a familial component; it is also sensitive to nutritional factors, rate of growth, and even exercise. 


Anatomy: Where two bones meet (joints) the end of each bone is covered in cartilage that acts as a cushion. The joint is also filled with a lubricating fluid to ensure smooth action. 


Effects: OCD may manifest as a crack or a floating chip (also known as a joint mouse). Cracks are typically less painful than a chip as the chip may move around inside the joint. Discomfort and pain are caused because the joint is no longer functioning smoothly. 


Severity: One or both shoulders may be affected. Damage is variable, ranging from a minor crack to multiple chips. 


Clinical Signs: OCD will typically show up in fast-growing, large breed dogs during their maximum growth period -usually 5-10 months-as an occasional or constant front-end limp that does not go away during normal activity. It may sometimes be confused with soft tissue damage (a bruise or muscle pull) or panosteotitis. There may or may not be discomfort on flexion of the shoulder. 


Diagnosis: OCD is typically diagnosed by radiographs (x-ray) in the case of a chip. Lesions are far more difficult to diagnose. 


Treatment: Treatment ranges from several weeks of crate rest in mild to moderate cases and surgery to remove chips in the more severe cases. 

Conservative treatment begins with crate rest and restricting activity. This means no strenuous exercise and leash walking for short distances. Avoid jumping as the front carries most of the body's weight. Pain medications are typically not recommended as they make the dog feel better and this makes them more likely to increase their activity level. If improvement is seen within two to three weeks, continue the crate rest for approximately eight weeks. You must then slowly reintroduce the dog to normal activities that will allow the strengthening of muscle tissue. If no improvement is seen, surgery may be the only option. 

Decisions to be made: 
• Should you go to a specialist? 
• Is conservative treatment (i.e. crate rest) an alternative to surgery? 
• If the dog is only lame on one side, but has radiographic evidence of OCD on both sides, do you do surgery on both? 
• Is arthroscopic surgery available or must traditional, more invasive surgery be performed? 
What are the cost ramifications of these decisions? 

Prevention: There is no absolute way to prevent OCD but there are several things you can do to lessen the chance. 
• Feed your dog the appropriate food-one that is well balanced and fed in appropriate amounts. 
• Avoid strenuous activity during the maximum growth periods (usually five to ten months of age) 
• Keep your dog lean. Additional pounds add extra stress to growing joints. 


Heritability: There is no simple answer to the question of OCD heritability. There is no doubt that the larger breed dogs are more at risk, and that there is at least some genetic component in the susceptibility of individual dogs. It is not known, however, whether OCD of the shoulder has any genetic component above and beyond that explained by high growth rate. In other words, it is not known whether OCD IS inherited within family groups or simply because Newfoundlands are giant dogs and by virtue of that fact will undoubtedly carry some risk of OCD. The genetic component is undoubtedly "polygenic". 

On the other hand, it is quite clear that over-nutrition and or over- supplementation, particularly of calcium, substantially increases the risk. Further, dogs in rural settings, dogs in multiple households, and dogs described as "playing" often with other dogs have higher incidences than their more sedate, urban, single dog counterparts. 

In short, OCD is a problem that can exacerbate any problems between breeders and buyers. For any particular dog, it will not be possible to determine whether the OCD resulted from having an inordinate genetic susceptibility, over-nutrition, or injury from roughhouse play. Probably all have contributed to some extent. Breeders should obviously monitor OCD in the puppies they produce and buyers should be aware that OCD in a single pup does not indicate careless or unscrupulous breeding practices. 

Reprinted from NewfTide 2004

 
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