Osteochondrosis and Lameness (elbow dysplasia)

At last, that special litter has arrived! It's been a long wait, but you're reasonably certain your pick of the litter, a magnificent retriever bitch you've named Casey, will be the future champion you need to keep an exceptional line going. Four months go by and Casey receives a clean bill of health from her veterinarian. Over the next two months, her progress continues just as you had hoped, except she develops a subtle limp in the right foreleg. Initially, you're not worried since it doesn't interfere with either her growth or her activity level. But your concerns mount as the limp gradually becomes more pronounced.

By six months of age the limp is quite obvious, and you now notice that when Casey stands, her right foreleg turns outward just a bit. There is also some stiffness in the morning when she first gets out of her crate, and she came up sore one day after running in the woods with the rest of the gang. Administering aspirin seemed to help, but since she's still lame, you decide to have Casey examined by the vet.

Casey flinches in pain when her right elbow is flexed, and the vet comments that there is some crepitus (grinding noise or sensation) in the joint. He also confirms your observation that Casey stands with her right foreleg abducted (rotated outward). He goes on to explain that there may be a problem with cartilage formation in Casey's elbow, and that he suspects a condition known as osteochondrosis. He recommends Casey have multiple radiographs (x-rays) taken under general anesthesia to help pinpoint the problem. Since Casey hasn't eaten yet that day, the vet offers to perform the procedure right away. You consent and sign the hospital admittance form.

In a daze, you wander into the waiting room with the empty lead in your hand. All of a sudden your brain is flooded with questions: What in the world is osteochondrosis? Why are so may x-rays necessary to diagnose it, and is it really essential to anesthetize the pup to obtain them? Is that why the estimate seems so costly? Can osteochondrosis be treated? Can it be prevented? And oh no, is it hereditary?

Later that afternoon, the vet calls to give you a presumptive diagnosis: osteochondrosis of the right elbow. He explains that abnormalities are visible on the radiographs, and although it is sometimes difficult to tell, he is fairly certain Casey has a type of osteochondrosis known as OCD. He recommends exploratory surgery of Casey's right elbow joint to confirm and, hopefully, correct the problem. Then he asks if you have any questions....

What is Osteochondrosis?

Osteochondrosis is the broad term for a developmental disease that results from a disturbance in the cartilage formation of a joint. Normally, cartilage provides the scaffolding upon which bone is laid down by the body and furnishes a smooth surface for the bones of a joint to glide across as they move.

There are at least three forms of osteochondrosis?: ununited anconeal process (UAP), fragmented coronoid process (FCP) and osteochondritis dissecans (OCD). When any one of these conditions occurs in the elbow, it is commonly referred to as UAP, the least common type of osteochondrosis lesion, results when the anconeal process (a part of the ulna, or long bone below the elbow, that helps form the elbow joint) fails to fuse normally to the ulna by 5 months of age.

FCP is the most common elbow osteochondrosis lesion. It results when the coronoid process (which, like the anconeal process, is simply another part of the ulna) becomes fragmented or develops fissures.OCD may be the form of osteochondrosis that is most familiar to breeders. It occurs when a tiny flap of cartilage separates (dissects) from the underlying bone, causing inflammation and pain in the joint, and ultimately leading to arthritis. In addition to being an elbow problem, OCD affects the shoulder, hock and stifle.

OCD was first recognized in the United States in 1964, and predominately affects large and giant breeds of dogs. However, cases involving smaller breeds have also been reported (see Table 1). Clinical signs of the disease are usually seen between 4 and 9 months of age, although dogs over 1 year old can be affected. As many as 36 percent of affected dogs, in fact, have been reported to be older than 12 months. The disease may be more common in males, but reports in the literature very on this point.

Approximately 43 to 65 percent of dogs with OCD are affected bilaterally. Furthermore, the problem may occur simultaneously in more than one joint, such as the shoulder and the elbow. And to complicate matters further, OCD may be in one joint, such as the shoulder, while UAP and FCP are in the elbow. This is why it is very importantly to take radiographs of multiple joints.

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What Causes Osteochondrosis?

Unfortunately, the exact cause of osteochondrosis is still unknown. Multiple factors, such as rapid growth, over-feeding and excessive weight gain, are thought to contribute to the development of the disease. Feeding free-choice has been suspected of causing skeletal problems, especially in dogs that overeat or are on highly supplemented diets. Other researchers have implicated various hormones in the development of osteochondrosis, due to their influence on the rapid growth phase. The roles of growth hormone, thyroid hormone and six hormones (androgens/estrogens) have been investigated but not proven as a cause. It is speculated that excessive levels of these hormones may result in abnormal cartilage development. A traumatic episode (falls, sprains, rough play or being hit by a car) early in life is also thought to possibly initiate and/or exacerbate cartilage changes.

Finally, what about a possible genetic influence? Although there is no conclusive evidence that osteochondrosis is hereditary, there have been reports of familial occurrences. Therefore, it has been suggested that dogs with a strong family history of osteochondrosis, or that have produced pups with the disease, should not be bred.

Fortunately for breeders, the Orthopedic Foundation for Animals (OFA) --- the same group that grades hips for hip dysplasia --- now operates a registry for elbow dysplasia (Figure 2). Hopefully, its existence will lead to a better understanding of canine osteochondrosis in general, including potential genetic transmission. Breeders are encouraged to ask their veterinarians to send elbow radiographs to OFA for evaluation.

When Should I Suspect Osteochondrosis?

Dogs affected with osteochondrosis typically have a history of lameness that comes and goes over several weeks to months. The lameness may be exacerbated by exercise or appear to be more pronounced after a rest period. Sometimes an episode of trauma makes matters worse. Owners may also notice that the dog stands with less weight on the affected leg. As with Casey, the leg may be held abducted or rotated outward; this is primarily seen when the problem is located in the elbow (see Figure 1). If OCD is in the hock joint, the affected hind leg may appear to be straight rather than normally angulated for the breed.

Fluid build-up (effusion) in the affected joint is another sign of osteochondrosis. This causes the joint to look and feel puffy and thickened as compared to the normal joint. However, effusion is very difficult to detect in an affected shoulder. Muscle loss (atrophy) may affect the entire limb as the dog attempts to shift its weight to the sound side. Atrophy of the foreleg shoulder muscles is especially noticeable in cases of shoulder OCD or in any form of elbow osteochondrosis. Pain and crepitus may be noted when the affected limb is palpated, and a limp or shortened stride may be observed during gaiting. Dogs may respond initially to an analgesic such as aspirin, but the lameness ultimately persists over time. If a pup exhibits any of the above signs, it is best to have it evaluated by a veterinarian as soon as possible.

How Is Osteochondrosis Diagnosed?

Besides relying on a history and physical exam, veterinarians typically need to use various diagnostic procedures to investigate the cause of the lameness.

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Radiographs are critical in helping to support a diagnosis of osteochondrosis. Remember, however, that osteochondrosis often occurs bilaterally and has the potential to affect several joints, so multiple radiographs are essential to effectively evaluate the severity of the dog's condition.

Your veterinarian will best be able to determine how many radiographic views are necessary. Hip radiographs may also be suggested for breeds prone to hip dysplasia so a total orthopedic assessment can be made.

Although hip dysplasia is not the same as osteochondrosis, it is wise to do preliminary screening of symptomatic dogs in breeds and families at risk of developing hip dysplasia. Certification by the OFA is limited to dogs at least 24 months of age, but preliminary screening (for dogs approximately 9 to 18 months old) can help eliminate severely affected animals from breeding programs. Dogs with borderline conformation should not be used for breeding and should be radiographed again after 24 months to establish their hip status.

Experts recommend that the patient be placed under heavy sedation, preferably general anesthesia. Although many dog owners are anxious about anesthesia, there is no other way to achieve the precise positioning and radiographic quality necessary to diagnose this often elusive disease. In fact, many general practitioners routinely consult a veterinary orthopedic specialist or radiologist to help confirm the presence of osteochondrosis, which under the best of circumstances can produce extremely subtle radiographic lesions.

The good news is that very safe anesthetics are available today, anesthetics that dramatically reduce the risk of complications. Furthermore, most of the patients being examine for osteochondrosis are young, which also reduces their level of risk. The bad news is that some of the newer anesthetics tend to be expensive, which in turn increases the cost of the investigation.

If the diagnosis is OCD, your veterinarian may point out something on the radiograph called a "joint mouse." Joint mice are small pieces of cartilage that become detached from the surface of the bone and float in the joint fluid. After they harden (calcify), they can be detected by x-ray (normal cartilage is not visible on x-rays). Joint mice, if there are any, are most easily seen in the shoulder. Their presence usually indicates a longstanding condition. Earlier in the disease process, the only radiographic lesions of OCD may resemble a flattened saucer or crater line on the affected bone surface.

Occasionally, the only radiographic changes seen with osteochondrosis are related to arthritis, which occurs when cartilage rubs the bone surfaces. These changes include bone spurs (known as osteophytes) and sclerosis--a thickened, increased density of the joint surface. Both of these radiographic signs are most typical of elbow dysplasia. Bear in mind, however, that radiographic indications of osteochondrosis may take time to become obvious. If your pup is persistently lame even though radiographs taken when it was young showed no apparent abnormalities, follow-up radiographs at a later date may be recommended.

Three other procedures often assist veterinarians in reaching a diagnosis of osteochondrosis. (1) The joint tap harvests fluid from an abnormally swollen joint. The fluid can then be evaluated to rule out infection or autoimmune-related disease as the cause of lameness. (2) A lyme disease titer may reveal evidence of infection with Lyme disease organism, Borrelia burgdoreri, which causes joint swelling and lameness in some dogs; and (3) If a conclusion cannot be reached on the basis of radiographs, blood work and joint fluid analysis, exploratory surgery may be indicated. This is especially helpful when dealing with elbow lameness. Since FCP and UAP can occur in the elbow in addition to OCD, surgical intervention may be the only way to arrive at an accurate diagnosis.

Can OCD Be Treated?

Two options are available to treat OCD in the dog: surgery and conservative medical management. In most cases, surgery is recommended for persistently lame dogs over 6 months of age. The decision to pursue surgery is further supported when radiographic changes are evident in the joint. The advantage of surgery is that it addresses what's going on in the affected joint before permanent arthritic and degenerative changes can occur.

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Basically, the surgeon opens and then explores the affected joint, searching for any loose or abnormal-looking pieces of cartilage. If a flap is found, it is removed and the area where the flap originated is curetted or scooped out. This helps stimulate the production of new, normal cartilage growth in that area.

The disadvantages of surgery include the risk of anesthesia, the cost of the procedure and the period of recovery, which can vary from a few weeks to months.

The post-operative prognosis for dogs with OCD of the shoulder is excellent --- almost 100 percent recover normal function of the limb. For other locations, especially the hock and elbow, surgery may not be as successful. Even without complete success, however, surgery may lessen the degree of lameness. The outcome largely depends upon the size and location of the lesion, the amount and extent of degenerative changes and the age of the dog. Surgery for OCD in multiple limbs may be performed at one time or in phases. This decision depends upon the surgeon, the dog and the owner.

Postoperatively, bandages are typically applied to support the limb and antibiotics are prescribed to guard against infection. A period of rest after surgery, with a gradual return to normal activity, is usually recommended.

Medical management of OCD, on the other hand, may be attempted in early cases or as an alternative for the older dog where surgery may not be as beneficial due to the extent of degenerative changes in the joint. The first rule of medical management is restricted activity.

Of course, the amount of restriction depends on the severity of the condition. Cage rest may be required in certain cases, but this is best determined by your veterinarian. Certainly, an elimination of all activities that require running, jumping or other strenuous activity is warranted for several weeks, or at least until the dog's condition can be reevaluated by a veterinarian. Sometimes, limited, less strenuous lead work may be permitted. Swimming is also a good form of exercise for OCD patients; in fact, it is recommended for many post-operative cases.

The use of anti-inflammatory medication in treating OCD is controversial. Some veterinarians feel that although pain and lameness are reduced by anti-inflammatory drugs, they may also slow healing of the cartilaginous defect. Polysufated glycosaminoglycan (Adequan) has reportedly helped promote healing of cartilage and has been used in the treatment of degenerative joint disease in dogs. However, it is not currently FDA-approved for use in dogs and, to date, there have been no controlled scientific studies to support its use in the treatment of canine OCD.

How Can Osteochondrosis Be Prevented?

The first step is to closely evaluate your pup's feeding program---especially if it is a large breed that typically experiences rapid growth. Be sure its diet provides, but does not exceed, the recommended nutrient requirements for growth. Avoid feeding excess fat, protein and minerals such as calcium or phosphorus. Provide only a good quality, nutritionally balanced dog food that has been specifically formulated for puppy growth. If it is not indicated on the label that the food has been shown to be nutritionally adequate for growth as determined by feeding trials approved by the Association of American Feed Control Officials (AAFCO), write to the manufacturer and request this information. If it is unavailable, the food should not be considered. It is vital to avoid overfeeding and excessive supplementation with vitamins and minerals, since these practices have been shown to put dogs at risk of the development of skeletal disorders such as OCD.

Vitamin C deficiency was once suggested as a causative factor in the development of certain canine skeletal diseases, including hip dysplasia. However, dogs, unlike people, are capable of synthesizing adequate amounts of this vitamin in their liver; therefore, there is no need for it to be added in a dog's diet. In addition, controlled studies have shown that vitamin C is of no value prophylactically and may, in fact, increase the probability of developing skeletal disease. Its excessive use has also been implicated in development of certain types of canine bladder stones.

If excessive fat deposits or skeletal problems should develop during the growth phase, the amount----rather than the quality---of the food should be reduced. It would also be beneficial to have elbow radiographs evaluated by the OFA so more information can be gathered about OCD and related conditions of the canine elbow.

Finally, use your best judgment when considering a breeding program using affected individuals or those with a strong family history of osteochondrosis.

Donna M. Manderino is a Diplomat of the American Board of Veterni8ary Practitioners. She and Maryanne S. Kern are practicing veterinarians in Park Ridge, New Jersey. They authors wish to thank Raymond G. Prata, DVM, Diplomat, American College of Veterinary Surgeons.

This article first appeared in the June 1993 AKC Gazette and is reprinted with permission.

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