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What is hip dysplasia?

To understand hip dysplasia we must have a basic understanding of the joint that is being affected. The hip joint forms the attachment of the hind leg to the body and is a ball and socket joint. The ball portion is the head of the femur while the socket (acetabulum) is located on the pelvis. In a normal joint the ball rotates freely within the socket. To facilitate movement the bones are shaped to perfectly match each other; with the socket surrounding the ball. To strengthen the joint, the two bones are held together by a strong ligament. The ligament attaches the femoral head directly to the acetabulum. Also, the joint capsule, which is a very strong band of connective tissue, encircles the two bones adding further stability. The area where the bones actually touch each other is called the articular surface. It is perfectly smooth and cushioned with a layer of spongy cartilage. In addition, the joint contains a highly viscous fluid that lubricates the articular surfaces. In a dog with normal hips, all of these factors work together to cause the joint to function smoothly and with stability.

Hip dysplasia is associated with abnormal joint structure and a laxity of the muscles, connective tissue, and ligaments that would normally support the joint. As joint laxity develops, the articular surfaces of the two bones lose contact with each other. This separation of the two bones within the joint is called a subluxation, and this causes a drastic change in the size and shape of the articular surfaces. Most dysplastic dogs are born with normal hips but due to their genetic make-up (and possibly other factors) the soft tissues that surround the joint develop abnormally causing the subluxation. It is this subluxation and the remodeling of the hip that leads to the symptoms we associate with this disease. Hip dysplasia may or may not be bilateral; affecting both the right and/or left hip.

What are the symptoms of hip dysplasia?

Dogs of all ages are subject to hip dysplasia and the resultant osteoarthritis. In severe cases, puppies as young as five months will begin to show pain and discomfort during and after exercise. The condition will worsen until even normal daily activities are painful. Without intervention, these dogs may eventually be unable to walk. In most cases, however, the symptoms do not begin to show until the middle or later years in the dog's life.

The symptoms are similar to those seen with other causes of arthritis in the hip. Dogs often walk or run with an altered gait. They may resist movements that require full extension or flexion of the rear legs. Many times, they run with a 'bunny hopping' gait. They will show stiffness and pain in the rear legs after exercise or first thing in the morning. They may also have difficulty climbing stairs. In milder cases dogs will warm-up out of the stiffness with movement and exercise. Some dogs will limp and many will become less willing to participate in normal daily activities. Many owners attribute the changes to normal aging but after treatment is initiated, they are surprised to see a more normal and pain-free gait return. As the condition progresses, most dogs will lose muscle tone and may even need assistance in getting up.

Who gets hip dysplasia?

Hip dysplasia can be found in dogs, cats, and humans, but for this article we are concentrating only on dogs. In dogs, it is primarily a disease of large and giant breeds. German Shepherds, Labrador Retrievers, Rottweilers, Great Danes, Golden Retrievers, and Saint Bernards appear to have a higher incidence, however, these are all very popular breeds and may be over represented because of their popularity. On the other hand, sighthounds such as the Greyhound or the Borzoi have a very low incidence of the disease. This disease can occur in medium-sized breeds and rarely in small breeds. It is primarily a disease of purebreds although it can happen in mixed breeds, particularly if it is a cross of two dogs that are prone to developing the disease.

What are the risk factors for the development of hip dysplasia?

Hip dysplasia is caused by a subluxation in the hip joint. This creates abnormal wear and erosion of the joint and as a result arthritis and pain develop. The disease process is fairly straightforward; the controversy starts when we try to determine what predisposes animals to contracting the disease.

Genetics: Researchers agree that hip dysplasia is a genetic disease. If a parent has hip dysplasia, then the animal's offspring are at greater risk for developing hip dysplasia. If there are no carriers of hip dysplasia in a dog's lineage, then it is highly unlikely he will not contract the disease. If there are genetic carriers, then he may contract the disease. We can greatly reduce the incidence of hip dysplasia through selective breeding. We can also increase the incidence through selectively breeding. We cannot, however, completely reproduce the disease through selective breeding. In other words, if you breed two dysplastic dogs, the offspring are much more likely to develop the disease but the offspring will not all have the same level of symptoms or even necessarily show any symptoms. The offspring from these dogs will, however, be carriers and the disease will most likely show up in their offspring in later generations. This is why it can be challenging to eradicate the disease from a breed or specific breeding line.

Nutrition: It appears that the amount of calories a dog consumes and when in the dog's life those calories are consumed have the biggest impact on whether or not a dog genetically prone to hip dysplasia will develop the disease.

Experimentally, it has been shown that obesity can increase the severity of the disease in genetically susceptible animals. It stands to reason that carrying around extra weight will exacerbate the degeneration of the joints in a dog; including the hip. Dogs that may have been born genetically prone to hip dysplasia and are overweight are therefore at a much higher risk of developing hip dysplasia and eventually osteoarthritis.

Another factor that may increase the incidence of hip dysplasia is rapid growth in puppies during the ages from three to ten months. Experimentally, the incidence has been increased in genetically susceptible dogs when they are given free choice food. In one study, Labrador Retriever puppies fed free choice for three years had a much higher incidence of hip dysplasia than their littermates who were fed the same diet but in an amount that was 25% less than that fed to the free-choice group.

Feeding a diet that has too much or too little calcium or other minerals can also have a detrimental effect on the development of the hip joint. However, with today's complete and balanced dog foods this has become a rare occurrence. The practice of feeding home-made dog foods is popular with some dog owners. These diets must be carefully monitored for proper nutritional balance; not only for calcium and the other essential minerals but for all nutrients.

Exercise: Exercise may be another risk factor. It appears that dogs that are genetically susceptible to the disease may have an increased incidence of disease if they over-exercised at a young age. But at the same time, we know that dogs with large and prominent leg muscle mass are less likely to contract the disease than dogs with small muscle mass. So, exercising and maintaining good muscle mass may actually decrease the incidence of the disease. Moderate exercise that strengthens the gluteal muscles, such as running and swimming, is probably a good idea. Whereas, activities that apply a lot of force to the joint are contraindicated. An example would be jumping activities such as playing Frisbee.

How is hip dysplasia diagnosed?

The diagnosis of canine hip dysplasia is typically made by combining: clinical signs of arthritis and pain, a complete physical exam, and radiographs (x-rays). If a dog is showing outward signs of arthritis, there are usually easily recognized changes in the joint that can be seen on radiographs. In addition, the veterinarian may even be able to feel looseness in the joint or may be able to elicit pain through extension and flexion of the rear leg. Regardless, the results are straightforward and usually not difficult to interpret.

However, about half of the animals that come in for a determination on the health of their hip joints are not showing physical signs, but are intended to be used for breeding. The breeder wants to ensure that the animal is not at great risk for transmitting the disease to his or her offspring. There are two different testing methods that can be performed. The traditional is OFA testing. The other relatively newer technique is the PennHip method.

OFA: The method used by the Orthopedic Foundation for Animals (OFA) has been the standard for many years. The OFA was established in 1966, and has become the world's largest all-breed registry. The OFA maintains a database of hip evaluations for hundreds of thousands of dogs. Radiographs are taken by a local veterinarian using specific guidelines and are then submitted to the OFA for evaluation and certification of the dog's hip status. Since the accuracy of radiological diagnosis of hip dysplasia using the OFA technique increases after 24 months of age, the OFA requires that the dog be at least two years of age at the time the radiographs are taken. Because some female dogs experience additional hip subluxation when they are in heat, pregnant or nursing the OFA recommends that the evaluation should not be performed during these times.

To get the correct presentation and ensure that the muscles are relaxed, the OFA recommends that the dog be anesthetized for the radiographs. OFA radiologists evaluate the hip joints for congruity, subluxation, the condition of the acetabulum, and the size, shape, and architecture of the femoral head and femoral neck. The radiographs are reviewed by three radiologists and a consensus score is assigned based on the animal's hip conformation relative to other individuals of the same breed and age. The OFA then places the evaluated dogs into one of seven categories. Normal hips are graded as: excellent, good or fair. If the consensus is unclear the dog is graded as borderline dysplastic. And dogs with obvious radiographic signs of hip dysplasia are graded as: mild, moderate, severely dysplastic. Dogs with hips scored as borderline or dysplastic (mild, moderate, severe) are not eligible to receive OFA breeding numbers.

The OFA will also provide preliminary evaluations (performed by one OFA radiologist) of dogs younger than 24 months of age to help breeders choose breeding stock. Reliability of the preliminary evaluation is between 70 and 100% depending on the breed.

PennHIP: The diagnostic method used by the University of Pennsylvania Hip Improvement Program (PennHIP) uses unique radiographic views of the dog's hips to more accurately identify and quantify joint laxity. This program was conceived in 1983 and became a usable system by 1993. To assure quality and repeatability among diagnostic centers using the PennHIP technique, veterinarians must take a special training course to become certified. Radiographs of the hips are taken with the dog under heavy sedation. These radiographs can be taken on a dog as young as 16 weeks. Two views are obtained with the hind limbs in neutral position to maximize joint laxity. These are known as the distraction and compression radiographic views. Weights and an external device are used to help push the head of the femur further into or away from the acetabulum. The amount of femoral head displacement (joint laxity) is quantified using a distraction index or DI. The DI ranges from 0 to 1 and is calculated by measuring the distance the center of the femoral head moves laterally from the center of the acetabulum and dividing it by the radius of the femoral head. A DI of 0 indicates a very tight joint. A DI of 1 indicates complete luxation with little or no coverage of the femoral head. A hip with a distraction index of 0.6 is 60% luxated and is twice as lax as a hip with a DI of 0.3. A third radiographic view is taken using the same positioning as the OFA. The "hip-extended" view is used to obtain additional information regarding the possible presence of degenerative joint disease (DJD) in the hip.

When the PennHIP DI was compared to the OFA scores for 65 dogs, all dogs scored as mildly, moderately, or severely dysplastic by the OFA method had a DI above 0.3.

Hip laxity as measured by the DI is strongly correlated with the future development of osteoarthritis. Hips with a DI below 0.3 rarely develop osteoarthritis. Although hips with a DI above 0.3 are considered "degenerative joint disease susceptible," not all hips with a DI greater than 0.3 will develop osteoarthritis. It is known that some hips with radiographically apparent laxity do not develop osteoarthritis. A means of differentiating lax hips that develop osteoarthritis from those that will not is important in developing a prognosis and making treatment or breeding recommendations. In one study, the DI obtained from dogs at four months of age was a good predictor of later osteoarthritis, though the 6 and 12-month indices were more accurate.

The PennHIP method has gained popularity and more and more veterinarians are becoming certified.

How is hip dysplasia treated surgically?

There are several surgical procedures available to treat hip dysplasia depending on the dog's age, body size, and the severity of the hip joint's degeneration.

Triple Pelvic Osteotomy (TPO): TPO is a procedure used in young dogs usually less than 10 months of age that have radiographs that show severe hip laxity, but have not developed damage to the joints. The procedure involves surgically breaking the pelvic bones and realigning the femoral head and acetabulum restoring the weight-bearing surface area and correcting femoral head subluxation. This is a major surgery and is expensive, but the surgery has been very successful on animals that meet the requirements.

Juvenile Pubic Symphysiodesis: A less invasive surgery for treating hip dysplasia is called Juvenile Pubic Symphysiodesis. This surgery prematurely fuses two pelvic bones together, allowing the other pelvic bones to develop normally. This changes the angle of the hips and improves the articulation of this joint, lessening the likelihood of osteoarthritis. Early diagnosis is critical, since the procedure must be done before 20 weeks of age, preferably 16 weeks, and before any signs of arthritis are evident.

Total Hip Replacement: This may be the best surgical option for dogs that have degenerative joint disease as a result of chronic hip dysplasia. Total hip replacement is a procedure that can produce a functionally normal joint, eliminate degenerative changes, and alleviate joint pain. The procedure involves the removal of the existing joint and replacing it with an artificial joint or prosthesis. To be a candidate for this procedure, the animal must be skeletally mature. With the new micro-prosthetics there is no minimum size limit. In addition, there is no maximum size limit. If both hips need to be replaced, there is a three-month period of rest recommended between the surgeries. As with the TPO surgery, this is an expensive procedure but it produces very good results. Most dogs return to a near normal level of activity without pain.

Femoral Head and Neck Excision: Femoral head and neck excision is a procedure in which the head of the femur is surgically removed and a fibrous pseudo-joint replaces the hip. This procedure is considered a salvage procedure and is used in cases where degenerative joint disease has occurred and total hip replacement is not feasible or if the expense of a total hip replacement is prohibitive. The resulting pseudo-joint will, in most cases, be free from pain and allow the animal to increase his activity, however, full range of motion and joint stability are decreased. For best results, the patient should weigh less than 40 pounds; however, the procedure may be performed on larger dogs.

How is hip dysplasia treated medically?

Medical management of hip dysplasia and osteoarthritis has greatly improved thanks to the introduction and approval of several new drugs. Because hip dysplasia is primarily an inherited condition, there are no products on the market that prevent its development. Through proper diet, exercise, supplements, anti-inflammatories, and pain relief, you may be able to decrease the progression of degenerative joint disease, but the looseness in the joint or bony changes will not change significantly.

Because of the high cost involved with corrective surgeries, medical management is many times the only realistic option for pet owners. Medical management is multifaceted. For the best results, several of the following modalities should be instituted.

Weight Management: Helping a dog maintain his recommended weight may be the single most important thing owner scan do for their pets. Surgical procedures and medical therapies will be far more successful if the animal is not overweight. You, as the owner, have control over what your dog eats. If you feed a quality food in an amount appropriate for your dog's size, breed and activity level and keep treats to a minimum, your dog should be able to maintain an ideal weight. Considering that more than half of the pets in the U.S. are overweight, there is a fair chance that many of the dogs with hip dysplasia/osteoarthritis are also overweight. If your dog is overweight, seek the advice of your veterinarian concerning a lower calorie dog food and an exercise program.

Exercise: Exercise is equally important in losing and/or maintaining the appropriate weight. Exercise that provides good range of motion and muscle building as well as limiting wear and tear on the joints is best. Leash walks, swimming, walking on treadmills, and slow jogging are excellent low-impact exercises. Bear in mind that an exercise program needs to be individualized for each dog based on the severity of the osteoarthritis, his weight, age, and physical condition. In general, too little exercise can be more detrimental than too much, however the wrong type of exercise can actually cause harm. While playing Frisbee can be very enjoyable and fun for the dog, it is extremely hard on his joints.

Remember, it is important to exercise daily; only exercising on weekends, for example, may cause more harm than good. Regular exercise in shorter sessions is always better than long work-outs on weekends. Warming the muscles prior to exercise and following exercise with a "warm-down" period are beneficial. Consult with your veterinarian regarding an exercise program appropriate for your dog.

Warmth and good sleeping areas: Most people with arthritis find that the symptoms tend to worsen in cold, damp weather. Keeping your pet warm, may help him be more comfortable. A pet sweater will help keep joints warmer. In addition, you may want to consider keeping the temperature in your home a little warmer.

Providing an orthopedic foam bed helps many dogs with arthritis. Beds with dome-shaped, orthopedic foam distribute weight evenly and reduce pressure on joints. They are also much easier for the pet to get out of. Place the bed in a warm spot away from drafts.

Massage and physical therapy: Your veterinarian or the veterinary staff can show you how to perform physical therapy and massage on your dog to help relax stiff muscles and promote a good range of motion in the joints. Remember, your dog is in pain, so start slowly and build trust. Begin by petting the area and work up to gently kneading the muscles around the joint with your fingertips using small, circular motions. Gradually work your way out to the surrounding muscles. Moist heat may also be beneficial.

Making daily activities less painful: Going up and down stairs is often difficult for arthritic dogs; it can make going outside to urinate and defecate very difficult. Many people build or buy ramps, especially on stairs leading to their yard, to make it easier for their dogs to go outside. Ramps also make car travel easier for arthritic dogs.

Oral Supplements

Glucosamine and Chondroitin: Glucosamine and chondroitin are two compounds that have been widely used to help manage osteoarthritis in both animals and humans.

Glucosamine is the major sugar found in glycosaminoglycans and hyaluronate, which are important building blocks in the synthesis and maintenance of joint cartilage in the joint. Chondroitin enhances the synthesis of glycosaminoglycans and inhibits damaging enzymes within the joint.

When a dog has hip dysplasia, the joint wears abnormally and the protective cartilage on the surface of the joint gets worn away and the resultant bone-to-bone contact creates pain. Glucosamine and chondroitin give the cartilage-forming cells (chondrocytes) the building blocks they need to synthesize new cartilage and to repair the existing damaged cartilage. These products are not painkillers; they work by actually healing the damage that has been done. These products generally take at least six weeks to begin to help heal the cartilage and most animals need to be maintained on these products the rest of their lives. These products are safe and show very few side effects. There are many different glucosamine/chondroitin products on the market, but they are not all created equal. Drs. Foster and Smith's line of Joint Care products or Cosequin are recommended.

Perna Mussels: Perna canaliculus, or green-lipped mussel, is an edible shellfish found off the shores of New Zealand. The soft tissue is separated from the shell, washed several times, frozen, and freeze-dried. It is then processed into a fine powder and added to joint care products. It is made up of 61% protein, 13% carbohydrates, 12% glycosaminoglycans (GAGs-an important component of connective tissue), 5% lipids, 5% minerals, and 4% water. It also contains glucosamine, a GAG precursor and one of the building blocks of cartilage. Glucosamine and GAGs are the compounds in the mussel believed to contribute to its beneficial effects.

Omega-3 Fatty Acids: Omega-3 fatty acids are often used for the management of the signs of atopy in dogs. Because of their anti-inflammatory properties, some have advocated their use in dogs with osteoarthritis.

Avocado/Soybean Unsaponifiables (ASUs): ASU's are an extract of avocados and soybeans. There is some very promising research that indicates that ASU's can help protect cartilage, support cartilage repair, and decrease the discomfort associated with osteoarthritis. ASU's are thought to enhance the action of glucosamine and chondroitin. ASU's are found in Doctors Foster and Smith Premium Joint Care 3.

Duralactin: Duralactin is a patented product obtained from the milk of grass-fed cows. It has been studied and marketed for the management of musculoskeletal disorders in dogs. This compound has anti-inflammatory properties and is available without a prescription.

It may be used as a primary supportive nutritional aid to help manage inflammation or in conjunction with non-steroidal anti-inflammatory drugs (NSAIDs) or corticosteroids.

Methyl-sulfonyl-methane (MSM): MSM is a natural, sulfur-containing compound produced by kelp. Sulfur is necessary for the production of collagen, glucosamine, and chondroitin. MSM is reported to enhance the structural integrity of connective tissue, and help reduce scar tissue by altering components that contribute to scar formation. MSM has been promoted as having powerful anti-inflammatory and pain reducing properties, and is thought to work by blocking the pain perception in certain nerve fibers before the pain impulse reaches the brain.

S-Adenosyl-L-methionine (SAMe, Denosyl SD4): A recent product, Denosyl SD4, has been advocated for the management of osteoarthritis in people. The efficacy of this product for the management of osteoarthritis in animals has not been fully determined; however it is being used as a treatment for liver disease in dogs and cats. It has both anti-inflammatory and pain relieving properties.

Injectable Disease-Modifying Osteoarthritis Agents:

Polysulfated Glycosaminoglycan (Adequan): Adequan is a product that is administered as an intramuscular injection. A series of shots are given over four weeks and very often this product produces favorable results. This product helps prevent the breakdown of cartilage and may help with the synthesis of new cartilage. The complete mechanism of action of this product is not completely understood, but appears to work on several different areas in cartilage protection and synthesis. The cost and the inconvenience of twice weekly injections are a deterrent to some owners, especially with the ease of giving oral glucosamine products.

Hyaluronic Acid (Legend): Hyaluronic acid is an important component of joint fluid. Including it in the management of osteoarthritis may protect the joint by increasing the viscosity of the joint fluid, reducing inflammation and scavenging free radicals. Most of the research on hyaluronic acid has been done in people and horses, but it may also be beneficial in dogs. Because this product is injected directly into the joint and it is not labeled for dogs its use must be under the direct supervision of a veterinarian.

Anti-inflammatory Drugs:

Buffered Aspirin: Buffered aspirin is also an anti-inflammatory and painkiller used in dogs. It can be used along with glucosamine/chondroitin products. With all aspirin products used in dogs, there is a risk of intestinal upset or in rare cases, gastric ulceration. Using buffered aspirin formulated for dogs makes dosage and administration much easier. Do NOT give your cat aspirin unless prescribed by your veterinarian.

Corticosteroids: Corticosteroids have been used for many years to treat the pain and inflammation associated with osteoarthritis, however, their use is controversial. Corticosteroids act as a potent anti-inflammatory, but unfortunately, they have many undesirable short and long-term side effects. Because of these side effects and the advent of newer, more specific drugs, corticosteroids are generally only used in older animals with flare-ups where all other pain control products have failed. Corticosteroids are a prescription product and come in both a pill and injectable form.

When it comes to preventing hip dysplasia, there is only one thing that researchers agree on; selective breeding is crucial. We know that through selectively breeding animals with certified hips, we can significantly reduce the incidence of hip dysplasia. We also know that we can increase the incidence of hip dysplasia if we choose to use dysplastic animals for breeding. Breeding two animals with excellent hips does not guarantee that all of the offspring will be free of hip dysplasia, but there will be a much lower incidence than if we breed two animals with fair or poor hips. If we only bred animals with excellent hips it would not take long to make hip dysplasia a rare occurrence. If owners insisted on only purchasing an animal that had parents and grandparents with certified good or excellent hips, or if breeders only bred these excellent animals, then the majority of the problems caused by hip dysplasia would be eliminated. For someone looking to purchase a dog, the best way to lower the possibility of getting an animal that develops hip dysplasia is to examine the incidence of hip dysplasia in the litter's lineage. It is best to examine the parents and grandparents out to three or four generations.

There are many different theories on how to prevent the progression of hip dysplasia. As discussed earlier, poor nutrition, inadequate or improper exercise, and increased body weight may all contribute to the severity of osteoarthritis after the hip dysplasia has developed. Following solid recommendations for exercise and nutrition may help, but will never come close to controlling or eliminating the disease if stricter requirements for certified hips are not instituted or demanded.

Summary

Hip dysplasia is a widespread condition that primarily affects large and giant breeds of dogs. There is a strong genetic link between parents that have hip dysplasia and the incidence in their offspring. There are probably other factors that contribute to the severity of the disease.

Osteoarthritis of the hip is the result of the degeneration of the joint due to a laxity caused by hip dysplasia. Surgical and medical treatments are targeted to prevent and treat the resulting osteoarthritis. The best way to prevent hip dysplasia is through selection of offspring whose parents and grandparents have been certified to have excellent hip conformation.

Who gets OCD?

OCD is primarily a problem in large or giant breed dogs. It has been reported in small dogs and cats, though it is not very common. It affects male dogs more frequently than females, most likely due to the males' larger size and increased stress on the joint. It generally occurs when the animal is between 4 and 10 months of age, though it can show up in older dogs. There are several breeds that despite being larger breeds have decreased incidences of the disease including the Doberman Pinscher, Collie, and Siberian Husky.

What are the symptoms of OCD?

OCD may affect the shoulder, elbow, knee or hock, although the shoulder is most commonly affected. The symptoms are lameness in the affected limb. Some dogs have a barely noticeable limp and others are unable to bear any weight on the leg. The lameness tends to worsen after periods of exercise and improves after rest. When it affects the shoulder, a shortened forelimb stride may be noted due to reluctance to flex and extend the shoulder joint. Occasionally, the disease will affect both limbs simultaneously and the dog may be reluctant to move.

How is OCD diagnosed?

Diagnosis is based on history, physical exam, and radiographs (x-rays). On physical exam, we notice joint pain. For instance, most healthy dogs show no resistance when their shoulder joint is fully flexed and extended. However, if they have an OCD lesion in their shoulder, they may resist shoulder manipulation and may even cry out in pain when it is attempted. In addition, this flexion and extension of the shoulder joint may worsen the lameness.

Radiographs of the affected joint are taken to confirm the diagnosis. The dog is often sedated so that full relaxation of the joint can be obtained. Several views of the affected joint and the healthy joint on the other side are taken for comparison. A change of the bone underneath the damaged cartilage is often visible. If the radiographs are not confirmatory but OCD is still suspected, radiographs may be taken again in 2 to 3 weeks.

What causes the formation of OCD?

The cause of OCD is considered to be multifactorial. It is thought that there are several factors that contribute to the formation of OCD lesions including trauma to the joint, genetics, rapid growth, hormone imbalances, and nutrition.

Trauma, whether chronic or acute, may contribute to the formation of OCD lesions. Injury to the surface cartilage may lead to the separation of the cartilage from the bone or cause a decrease in blood supply that leads to cartilage flap formation.

It appears that there is a genetic link between parents and offspring and the formation of the disease. Certain breeds and genetic lines are much more likely to develop the disease. Careful screening of parents against this disease is recommended during the selection of all breeding animals.

OCD usually occurs during periods of rapid growth. Therefore, it has been suggested that nutrition that creates rapid growth may lead to the increase in incidence of the disease.

How is OCD treated?

There are currently two ways to treat OCD, conservative medical treatment or surgical removal of the lesion. Conservative treatment may be indicated for dogs that have early mild symptoms of OCD or where a specific lesion cannot be identified on radiographs. Conservative treatment consists of strict rest for 4 to 8 weeks. Leash walking is permitted but no running or playing is allowed. Anti-inflammatories and painkillers such as carprofen (Rimadyl) may be indicated. In addition, the use of glucosamine/chondroitin products has been suggested, yet there are no current studies that confirm their beneficial use in this particular disease. Conservative treatment may be difficult in young, active puppies who may still need to undergo surgery, if the symptoms do not improve.

Surgery is indicated in animals that show severe symptoms, in cases where large lesions are identified on radiographs or when conservative treatments fail. The surgery is very straightforward. The affected joint is opened and the offending flap, defect, or joint mouse is removed. The prognosis is generally good when the shoulder joint is affected. With other joints, degenerative joint disease (osteoarthritis) is more common. When the elbow is affected, the OCD may contribute to the development of other abnormalities in that joint.

How is OCD prevented?

Prevention consists of careful selective breeding that avoids the breeding of animals with a history of OCD. Young large and giant breed dogs should not undergo strenuous activity, particularly jumping activities. Housing on hard concrete surfaces has been linked to increased OCD lesions in pigs and may also contribute to problems in the dog. Providing a good balanced diet that promotes even, sustained growth is also recommended. Talk to your veterinarian about what is best to feed your dog.

Summary

OCD is a cartilage problem that affects young large and giant breed dogs. It is due to several factors including genetics, trauma, rapid growth, and nutrition. Treatment is either conservative including strict rest, or surgical removal of the damaged cartilage. Prevention is aimed at good genetic selection, reduced activity, and careful feeding.

A small breed dog runs across the yard chasing a tossed ball. In mid-stride, he yelps in pain and pulls his left hind leg off of the ground. After a second, he continues limping on in three-legged fashion. After ten minutes, the rear leg drops back down to the ground and he uses it normally. This episode occurs maybe once a week. It never really seems to bother him that much – a yip of pain, a short period of lameness, and in a few minutes he is back to his old self. Typically, he is a small or toy breed such as a Lhasa Apso, Pekingese, Pomeranian, Poodle, or Boston Bull.

A luxating patella may affect some animals much more severely. They may hold the leg up for several days and show considerable discomfort. Dogs who have a luxating patella on both hind legs may change their entire posture, dropping their hindquarters and holding the rear legs farther out from the body as they walk. Those most severely affected may not even use their rear legs, walking by balancing themselves on their front legs like a circus act, holding their hindquarters completely off the ground.

Normal knee anatomy

The patella is the bone we know as the knee cap. A groove in the end of the femur allows the patella to glide up and down when the knee joint is bent back and forth. In so doing, the patella guides the action of the quadriceps muscle in the lower leg. The patella also protects the knee joint.

Looking at the lower front portion of the femur (the thigh bone) in a normal dog, you will notice two bony ridges that form a fairly deep groove in which the patella is supposed to slide up and down. These structures limit the patella’s movement to one restricted place, and in so doing, control the activity of the quadriceps muscle.

The entire system is constantly lubricated by joint fluid. It works so that there is total freedom of motion between the structures.

What occurs when the patella is luxated?

In some dogs, because of malformation or trauma, the ridges forming the patellar groove are not prominent, and a too-shallow groove is created. In a dog with shallow grooves, the patella will luxate (jump out of the groove) sideways, especially toward the inside. This causes the leg to 'lock up' with the foot held off the ground.

When the patella luxates from the groove of the femur, it usually cannot return to its normal position until the quadriceps muscle relaxes and increases in length. This explains why the affected dog may be forced to hold his leg up for a few minutes or so after the initial incident. While the muscles are contracted and the patella is luxated from its correct position, the joint is held in the flexed or bent position. The yip is from the pain caused by the knee cap sliding across the bony ridges of the femur. Once out of position, the animal feels no discomfort and continues his activity.

Which dogs are at risk of having a luxated patella?

Smaller breeds of dogs, especially Miniature and Toy Poodles, have the highest incidence of patella luxation. Genetics can play a role.

In certain breeds that have extremely short legs such as the Basset Hound or Dachshund, patellar luxation is thought to be secondary to the abnormal shape of the femur and tibia. The curvatures of the bones in these breeds work in conjunction with the forces of the quadriceps muscles to displace the patella to the inside. Please do not misunderstand – not all members of these breeds are affected with patellar luxation, only a small portion.

What are the symptoms?

Most dogs are middle-aged, with a history of intermittent (on-again-off-again) lameness in the affected rear leg(s). An affected dog commonly stops and cries out in pain as he is running. The affected leg will be extended rearward, and for a while the dog is unable to flex it back into the normal position.

What are the risks?

Uncorrected, the patellar ridges will wear, the groove will become even shallower, and the dog will become progressively more lame. Arthritis will prematurely affect the joint, causing a permanently swollen knee with poor mobility. Therefore, a good evaluation needs to be done by your veterinarian early in the condition to prevent long-term arthritic crippling.

Treatment for Luxating Patellas

As would be expected, medical therapy has little corrective ability in this disorder and surgery is therefore required and is the treatment of choice. A surgical treatment is not necessary in every individual with this condition.

Surgery can alter both the affected structures and the movement of the patella. The groove at the base of the femur may be surgically deepened to better contain the knee cap. This procedure is known as a trochlear modification. The knee cap itself may be "tied down" laterally (on the outside) to prevent it from deviating medially (toward the inside). This is called a lateral imbrication. The bony protuberance at the site of the attachment of the quadriceps tendon on the tibia may be cut off and then re-attached in a more lateral position. This is termed a tibial crest transposition. All of these procedures work well and the type performed depends on the individual case and the clinician. The animal should respond quickly after surgery and is usually completely recovered within 30-60 days, depending upon the procedure.

Breeding Considerations

Because of the strong genetic relationships, we really feel that animals with this disorder should not be used for breeding. They can still be excellent pets - and those that do require surgery will usually lead perfectly normal lives without any restrictions on activity.

The knee is prone to a number of injuries as any football player will tell you. One of the most common knee injuries in dogs is a ruptured cruciate ligament.

Knee anatomy

The knee is a joint that is formed by three bones: Femur (the long bone extending down from the hip); Tibia (the bone between the knee and ankle); and Patella (the kneecap). These bones are joined together by a number of ligaments, which are tough fibrous bands of tissue. Two ligaments crisscross in the joint from the femur to the tibia and are called cruciate ligaments (cruciate means cross). The one towards the front of the leg is called the anterior cruciate ligament and the one crossing behind it is the posterior cruciate ligament. These ligaments prevent the ends of the femur and tibia from moving back and forth across each other.

A rupture of the anterior cruciate ligament (ACL)

Symptoms of a ruptured cruciate ligament

Dogs who have ruptured their cruciate ligament will appear suddenly lame, and usually hold the foot of the affected leg off the ground. The knee may become swollen. In time, the dog may start to use the leg again, but often lameness returns. Dogs with a degenerating ACL may also show some pain, and there may be some swelling in the joint.

Diagnosis of a ruptured cruciate ligament

The diagnosis of a ruptured cruciate ligament is made through observing abnormal movement of the joint. A veterinarian will place one hand around the femur and one around the tibia in a precise manner. By applying pressure on the knee, the veterinarian will feel the bones move abnormally in what is called a 'drawer sign.' It is called that because the movement of the femur in relation to the tibia is similar to pulling and pushing in the drawer of a cabinet. If an animal is in a lot of pain, or very nervous, the muscles near the knee may be so tense that they prevent the drawer movement from occurring. If a veterinarian suspects a ruptured cruciate ligament in a dog but cannot elicit the drawer sign, the dog may be heavily sedated to relax the muscles and then re-examined for the drawer sign. Many dogs with a ruptured cruciate ligament will have swelling on the inside aspect of the knee, and this is called a medial buttress. Radiographs are commonly performed to better assess the amount of arthritis that may be present.

Treatment of a ruptured cruciate ligament

If the ligament is completely torn, the dog (especially a large dog) is generally treated with surgery. There are several different methods used to repair the knee joint when an anterior ligament is torn. Some entail using synthetic suture material, or a portion of adjacent fibrous tissue to basically re-create the ligament. The suture or tissue is made to extend from the outside lower portion of the femur to the inside upper portion of the tibia. After the surgery, the dog must be strictly confined for 2 weeks. By day 10 after surgery, most dogs touch the toe of the affected leg to the ground and will start bearing minimal weight on the leg. Once the dog has reached this point, it is often very difficult to keep the dog quiet until complete healing has taken place. The dog generally has to be restricted to only leash walking for a minimum of 4-6 more weeks; the exact amount of time depends upon the extent of the injury and the corrective procedure performed. This is extremely important to prevent the surgical correction from tearing. The veterinarian's instructions regarding exercise during the recovery period should be followed very carefully.

Another surgery that may be performed is the tibial plateau leveling osteotomy (TPLO). In this procedure, a portion of the tibia is cut, moved, and reattached to a different portion of the tibia using plates and screws. By changing the conformation of the tibia, the joint is stabilized. This is a technically difficult surgery but it has shown to produce excellent results, often with less arthritis. This surgery is especially recommended for dogs over 50 pounds in weight. The recovery period is similar to that with the other surgical procedures.

The third procedure that may be used is the tibial tuberosity advancement (TTA). This is another surgery in which a different portion of the tibia is cut, and allowed to heal at a different angle to change the mechanical stresses on the joint. As with the TPLO, this surgery is more complex and it requires special equipment and training.

In some instances, if the cruciate ligament is only partially torn, the animal is older, has medical conditions which could affect healing, or the owners will not be able to keep the dog quiet for a number of weeks after surgery, medical treatment is used. This basically consists of controlling the dog's activity for 8-12 weeks. Swimming and low-impact exercise (walking) may be done on a controlled basis, as instructed by a veterinarian, to keep up muscle strength. If overweight, the dog should be placed on a reduced-calorie diet. Nonsteroidal anti-inflammatory drugs (NSAIDS) such as carprofen, etodolac, meloxicam, deracoxib, buffered aspirin, or other medications are often used to reduce inflammation in the joint and relieve pain. (Do NOT give your cat aspirin unless prescribed by your veterinarian.) Products containing glucosamine, chondroitin, perna mussel, polysulfated glycosaminoglycans, and other chondroprotective agents are often recommended, as well.

If a dog with a ruptured cruciate is not treated, severe degenerative joint disease (arthritis) usually occurs. In addition, because the dog favors the affected leg, he will generally put more weight on the unaffected leg. It is not unusual for the dog to rupture the anterior cruciate ligament on that leg as well because of the increased stress on the leg.

Prognosis

If the dog's exercise is restricted as instructed, and overweight dogs return to normal body weight, the prognosis is good. Depending on the amount of injury to the knee and length of time between the injury and correction of the problem, degenerative joint disease may occur as the pet ages.