Elbow Dysplasia

OVERVIEW: 

 

Elbow dysplasia is a term used to describe several closely related medical conditions which impact the elbows of domestic dogs.  Some dogs with elbow dysplasia only exhibit one of the underlying conditions, although many exhibit two or more.  Elbow dysplasia is one of the most common genetically-inherited musculoskeletal conditions found in domestic dogs and is especially common in large and giant breeds.  Elbow dysplasia is also known as any one of the conditions which may be responsible for its presence to include osteochondrosis of the elbow,  osteochondritis dissecans/OCD, osteochondritis of the medial humeral condyle, fragmented medial coronoid process and ununited anconeal process, and incongruent elbow.

 

Three bones comprise the elbows of normal adult dogs, the humerus, radius, and ulna.  The humerus, or upper arm bone, connects the arm to the shoulder and ends in the elbow.  The radius and ulna, which extend from the elbow to the hand, function as essentially a single bone.  All three bones have unique features which allow them to connect together properly and provide the greatest amount of stable movement.  At the end of the humerus are two rounded knobs known as the lateral and medial condyles.  Between the two condyles is the supratrochlear foramen, a hole that extends completely through the bone.  The upper end of the ulna has a hook-like structure known as the anconeal process which fits into the supratrochlear foramen and the troclear notch, a curved ridge that fits between the two condyles of the humerus.  On either side of the troclear notch are the medial and lateral coronoid processes, which the medial and lateral condyles rest on.  The upper end of the radius lies between the two coronoid processes and helps support the weight of the dog.  All of the surfaces on all three bones are covered in cartilage and should be perfectly smooth.  A fluid-filled capsule encases the entire joint.  The joint fluid within provides constant lubrication for skeletal movements.  This system works so well that dogs can support their entire weight and have a wide range of movement, albeit not nearly to the extent that humans have.

 

Each of the conditions which can cause elbow dysplasia impacts the normal joint structure in a different way.  Dogs suffering from osteochondrosis of the elbow have an abnormality of the cartilage which lies in between the bones and prevents them from rubbing directly against each other.  In many dogs, there is something so wrong with the cartilage that a portion of it physically loosens or even separates entirely from the underlying bone.  This condition is known as osteochondritis dissecans and is extremely painful whether the cartilage is hanging on to the bone partially like a flap or completely free and floating around freely in the fluid capsule.  In domestic dogs, the elbow cartilage most likely to separate from the bone is that on the medial side of the humerus, a condition known specifically as osteochondritis dissecans of the medial humeral condyle.  

 

Much like humans, dogs are born with several more bones than they have as adults.  This is because several bones fuse together as they grow, eventually becoming a single structure.  Such a fusion occurs in the ulna, where the coronoid and anconeal processes are initially unique bones.  Sometime this fusion never actually occurs or disintegrates after it has begun.  When the medial coronoid process is the bone so impacted, the condition is known as fragmentation of the medial coronoid process.  When the anconeal process is the bone so impacted, the condition is known as ununited anconeal process.  In those dogs suffering from either fragmentation of the medial coronoid process or ununited anconeal process, the ulna and the smaller bone may either be partially connected with ligaments and/or cartilage, or the smaller bone may be entirely disconnected and floating free within the joint.

 

The bones of the body are designed to fit together perfectly, like the pieces of the puzzle.  In order to function properly, neighboring bones must grow at the same rate so that they continue to fit together.  Unfortunately, sometimes the growth rate of neighboring bones differs dramatically, leaving a dog with bones that do not fit properly together due to size differences.  Sometimes, this occurs within the elbow of dog resulting in a condition known as incongruent elbow.  Dogs suffering from incongruent elbow have radii that are either too large or too small for the radius and ulna (or vice versa). 

 

Regardless of the exact underlying condition, the impacts of elbow dysplasia are quite similar, and in any case many dogs suffer from multiple underlying conditions at the same time, especially osteochondritis dissecans and fragmented medial coronoid process.  The bones in the elbow joint experience a significant amount of stress merely doing their job.  They not only have to support the animal’s entire weight, but they also have to move freely, rub up against each other, and experience the stress of walking and moving.  A good analogy is the parts of a car wheel, which must perform all of the same functions.  The elbows of normal dogs are up to this stress, but those suffering from elbow dysplasia are not.  When the bones of the elbow do not fit together properly, a number of effects occur.  First, the bones move in ways which they were not meant to, usually less tightly.  This weakens the joint, making it both incapable of supporting as much weight and making it more difficult and challenging to support what weight it can.  It also causes the bones to move up against each other in unnatural ways.  If untreated, this unnatural rubbing will cause damage to the cartilage and ligaments in between the bones, damage which can be quite painful.  Eventually, this damage may become permanent, resulting in arthritis.  If the cartilage completely wears off, the bones will rub up against each other directly, causing even more pain.  The situation is even worse in dogs which have a piece of bone or cartilage floating freely within the joint.  Not only is the entire joint weakened  and misshapen as a result, but the floating bone will jab up against fleshy tissue and cause very significant pain (imagine a piece of sharp shrapnel stuck inside the body that pokes and stabs the tissue whenever it is moved).

 

Elbow dysplasia can develop at any point in a dog’s life, but usually develops either quite late in life as a result of general body deterioration or between the ages of 4 and 12 months as a result of a dog’s natural growth to full adult size.  In the vast majority of cases, elbow dysplasia is caused primarily or entirely by genetics, although it can also occur as a result of accident or injury.  Many researchers believe that external factors such as diet and exercise have a significant impact on the timing and severity of elbow dysplasia’s onset, and some believe that they may be able to cause the condition on their own (although this is currently far from universally accepted).  The severity of elbow dysplasia varies significantly from animal to animal.  Minor cases may cause only mild discomfort, while severe cases may cause crippling pain and even permanent lameness.  Most dogs which develop elbow dysplasia are equally impacted in both legs.  However, there are many exceptions.  Some dogs may be dysplastic in one elbow and completely normal in the other.  The condition’s severity may also be quite different in both elbows.  Generally, the same underlying condition(s) will cause elbow dysplasia in both elbows, but there are rare cases where two elbows on the same dog are dysplastic for different reasons.

 

RISK FACTORS: 

 

Age – Although elbow dysplasia may appear at any age, the vast majority of dogs begin to exhibit symptoms at one of two points in their lives.  Most dogs first show symptoms while they are still adolescents.  It is most common for symptoms to first appear between 7 and 10 months of age, although any age between 4 and 12 months is fairly typical.  Many other dogs first exhibit symptoms when they are advanced in age, usually after about 6 depending on the breed.

 

Size – Large dogs are much more likely to develop elbow dysplasia than small dogs, and giant dogs are much more likely to develop elbow dysplasia than large dogs.  This is due to a combination of genetic inheritance, growth patterns in large breeds, and the extra stress than added weight puts onto joints.  While less common, elbow dysplasia is still regularly seen in small and medium sized dogs as well.

 

Genetics – There is no better predictive factor for elbow dysplasia than genetics.  Dogs with a close relative which has been diagnosed with elbow dysplasia are much more likely to develop the condition than other dogs, especially if the close relative is a parent or littermate.

 

Gender – Male dogs are considerably more likely to develop elbow dysplasia.  This is thought to be at least partially because male dogs are usually larger than females, an average difference which may be fifty pounds or more in some giant breeds.

 

Breed – Elbow dysplasia is very common and widespread.  The condition has been diagnosed in essentially all large and giant breeds (with a very few exceptions), and is increasingly being detected in small or medium sized breeds as well.  However, some breeds are considerably more likely to develop elbow dysplasia than others including the Basset Hound, Bernese Mountain Dog, Bloodhound, Bouvier des Flandres, Chow Chow, Dogue de Bordeaux, English Bulldog, English Mastiff, German Shepherd Dog, Golden Retriever, Great Pyrenees, Irish Wolfhound, Labrador Retriever, Neapolitan Mastiff, Newfoundland Dog, Rottweiler, St. Bernard, and Weimaraner.  

 

SIGNS & SYMPTOMS: 

 

The first sign of elbow dysplasia is usually a limp.  The exact nature of the limp depends on the case.  When only a single leg is affected by elbow dysplasia, some dogs will only seem to slightly favor the other leg, while others will put no weight on the affected leg whatsoever.  Some dogs keep the leg raised while others hold it out from the body.  Dogs with elbow dysplasia usually do not limp, per se, unless one leg happens to be bothering them more at that specific moment.  Instead, these dogs generally have an unusual gate.  They may seem to walk gingerly or slowly.  Many either hold their elbows out from their body when they walk or turn their feet noticeably outwards.  In most cases, such movement changes are very mild and may be nearly unnoticeable, even by veterinarians.  These symptoms will gradually worsen as the dog ages.  This progression can be much faster, however, and some dogs may develop a full limp seemingly overnight.  Any unusual movement or limping is usually most pronounced after a dog has gotten up from rest or just finished physical activity. 

 

As the condition worsens, the dog begins to experience progressively more pain and discomfort.  Because activity makes the pain worse, most affected dogs become progressively less active.  Many are described as lazy or unenergetic.  Affected dogs often play less than normal dogs and for shorter time periods.  As the condition worsens, dogs may refuse to go up stairs, jump, and may even be extremely reluctant to walk to their food dish.  Many dogs become very resistant to anything touching their elbows, and may react with fear or even aggression when an attempt to do so is made.  In some cases, the elbow becomes visibly swollen.  This swelling may either be permanent or last temporarily after exercises.  Dogs which have been resisting moving their elbows for long periods of time often begin to show muscle atrophy and weight gin due to lack of exercise. 

 

The timing onset at the progression of symptoms varies substantially from dog to dog.  In most cases, dogs first exhibit symptoms between the ages of 4 and 12 months.  These symptoms usually get progressively worse for several months.  In most cases, the symptoms improve dramatically or disappear entirely once the dog reaches an age of 12 to 18 months of age.  This improvement is probably the result of several factors including the dog reaching its maximum size and the dog adapting to the constant discomfort.  Symptoms are usually substantially reduced for a number of years, when they will start back up again.  In many cases, this is the result of the condition progressing to the point where it is so painful that the dog can no longer cope. 

 

DIAGNOSIS & TESTS: 

 

Diagnosis for elbow dysplasia is usually a two or three step process.  The first step is for the veterinarian to take into account many factors specific to the case.  The symptoms which an individual dog is displaying are important, as are its age, breed, and family history if known.  Ideally, the veterinarian will attempt to observe any limps or unusual movement themselves, but this is not always possible, especially in minor cases.  The next step is to perform a physical examination of the elbow and other parts of the legs.  Veterinarians will attempt to see if there is swelling and grating in the elbow, and also to see the dog’s reaction to their elbows being manipulated.  Other parts of the legs will also be examined to see if they are in fact the problem.  Unfortunately, a conclusive diagnosis of elbow dysplasia cannot be made with an external exam alone.  This is because a very wide range of conditions have symptoms which closely match those of elbow dysplasia, some of which only impact the elbow indirectly, such as hip dysplasia, broken and chipped bones, torn ligaments, muscle pulls, severe sprains, and even some nervous system disorders.

 

If elbow dysplasia is suspected to be the cause of a dog’s symptoms, x-rays must be taken (or other internal body images such as those from a CAT scan) to provide a definitive diagnosis.  Because the x-rays required to diagnose elbow dysplasia often require the leg to be maneuvered in painful ways and held in place for a significant period of time, the animal is often sedated with anesthesia.  This both ensures that the animal experiences as little pain and emotional trauma as possible and that the x-rays taken will be sufficient for a diagnosis.  Even with x-rays, elbow dysplasia can be very challenging to diagnose.  This is because many dysplastic elbows exhibit such minor differences from normal elbows that they are nearly impossible for even experienced veterinarians to detect.  For this reason, many veterinarians will send off such x-rays to veterinary radiology specialists.  Of the potential underlying causes for elbow dysplasia, an ununited anconeal process is definitely the easiest to diagnose and the clearest on most x-rays.  The other causes are usually substantially more difficult to diagnose, unless the condition is so severe that a fragment of bone or cartilage has completely broken free.

 

CONVENTIONAL TREATMENT & MANAGEMENT: 

 

Elbow dysplasia is almost always an inherent part of a dog’s genetic makeup and is with that dog from the time it is conceived.  This means that it is not technically possible to cure elbow dysplasia, although its symptoms can be dramatically reduced with treatment.  Treatment options for elbow dysplasia vary tremendously, and each individual case must be treated in a unique manner depending on the underlying condition or conditions, the severity of each, the age of the dog, the amount of pain the dog appears to be in, and a number of other case specific factors.  In cases of osteochondrosis of the elbow and fragmented coronoid processes where there is not a loose bone fragment in the joint, the best option is usually to treat the problem medically rather than surgically.  In the case of very old dogs or those with some other medical condition which makes surgery especially risky, medical treatment is often advisable as well.  In the case of ununited anconeal process or where there is a loose bone fragment surgery combines with medical treatment is often the best option.  Very young puppies may also benefit from surgery if it can prevent problems from developing later in life.  In the case of incongruent elbow, the severity of the incongruence will determine whether surgery is the best option.

 

Medical treatment options for elbow dysplasia have three major goals, to reduce the animal’s pain, to ensure that the animal maintains a necessary level of activity to stay healthy, and to reduce any additional pressure on the joint to the greatest extent possible.  Anti-inflammatory drugs are very frequently prescribed to reduce the swelling, pressure, and pain caused by elbow dysplasia, especially non-steroidal anti-inflammatory drugs (NSAIDS).  In cases where the pain is more severe, stronger pain killers may prove necessary.  The heavier the dog, the greater strain is placed on the elbow joint and its part.  Because overweight dogs experience more and worse symptoms from elbow dysplasia keeping affected dogs in the proper shape is very important.  Diets may be necessary to induce weight loss.  Exercise is also necessary, but providing sufficient amounts can prove challenging for dogs in pain.  Veterinarians often recommend completely changing a dog’s exercise regimen and replacing it with low impact exercises.  In particular, swimming is a very popular and often successful choice. 

 

Surgical options for elbow dysplasia vary widely depending on the age of the dog and the features of an individual case.  Dog’s under the age of 1 year of age that have not stopped growing are the best candidates for surgery because they have both more options and greater changes of full recovery.  When a young dog has an ununited anconeal process, there are two options.  The anconeal process can sometimes be reattached with screws, or the ulna can sometimes be cut to relieve stress and allow the anconeal process to attach naturally, a procedure known as an ulnar osteotomy.  Generally, if elbow dysplasia can be identified and surgically repaired early enough, the dog will be prevented from developing osteoarthritis, and many such repaired dogs will go through life as though nothing was ever wrong.  For older dogs, as well as young dogs with other forms of elbow dysplasia, there are fewer options and a less optimistic prognosis.  When there is a fragment of bone or cartilage floating free in the knee, surgeries to remove that fragment are almost always advisable and helpful.  In cases of incongruent elbows, the three bones of the elbow can be surgically sculpted to fit better together, a procedure which is very challenging and has somewhat mixed results.  Although each individual case is different, most older dogs suffering from osteochondrosis and fragmented coronoid process benefit substantially less from surgery than other cases.  While most of these dogs can have their pain level substantially reduced, it is generally not to the extent of other surgical options. 

 

There are two options available for dogs with very severe elbow dysplasia, both of which are considered absolute last resorts.  One is total elbow replacement, where the entire elbow is removed and replaced with an artificial prosthesis.  Because the elbow is a significantly more complicated joint than the hip, elbow replacements are considerably more challenging to perform and considerably less likely to succeed.  The recovery time can also be very long and a limp will almost certainly permanently remain.  Despite these drawbacks, an estimated 80% to 85% of dogs do see improvement after elbow replacement.  Another option is arthrodesis, a procedure which physically fuses the bones of the elbow together.  This procedure eliminates essentially all of the pain of elbow dysplasia, but it leaves the leg completely unable to bend.  The dog will therefore have a permanent limp and severely restricted motion.

 

POTENTIAL COMPLICATIONS: 

 

There are numerous possible complications from elbow dysplasia.  By far the most common is osteoarthritis, which causes chronic pain and soreness.  The pain and soreness caused by elbow dysplasia and the osteoarthritis which follows worsen over time.  As the pain worsens, the dog usually avoids physical activity to the greatest extent possible.  This can result in weight gain and muscle atrophy, both of which put greater stress on the elbow joint and therefore worsen the problem.  At the same time, the dog will attempt to walk in a manner that puts as little stress on its joints as possible.  This results in a highly unnatural form of locomotion such as walking with elbows extended or feet pointing outwards.  If the dog moves in such a way for a long enough period of time, its entire musculo-skeletal structure will be strained in ways which it was not supposed to be.  Osteoarthritis may develop across the entire body as bones rub up against each other in ways which they were not supposed to.  The dog may also put itself at risk of skeletal injuries such as torn ligaments, broken bones, and back injuries.  In severe cases, elbow dysplasia may lead to a total and permanent lameness in an affected leg.

 

There are many potential complications from the treatment of elbow dysplasia.  Any of the medications used to reduce the pain caused by elbow dysplasia may have potential side effects, especially when they work in tandem with other medications.  Veterinarians will be able to discuss the potential side effects of any particular drug which they prescribe. Elbow dysplasia surgery can also be quite risky.  Some dogs are allergic or sensitive to anesthesia, and may experience difficulty breathing, heart palpitations, anabolic shock, and even death when put under.  There is also always a risk that something will go wrong and the dog will bleed to death, especially if the dog has an undiagnosed bleeding disorder such as Von Willebrand’s disease.  Elbow dysplasia surgeries can be particularly tricky because the elbow is such a complex and delicate joint.  There is always an inherent risk that such procedures may either not have the desired effect or even exacerbate the problem, even when performed by the most highly skilled veterinarians.  Many elbow dysplasia surgeries such as total elbow replacement and arthrodesis will leave a dog with permanently restricted movement.  If a dog is forced to overcompensate in other ways, it may develop musculoskeletal problems elsewhere in the body such as osteoarthritis or back injury. 

 

 

HOLISTIC REMEDIES: 

 

Elbow dysplasia is caused by an inherent genetic defect which causes an internal and permanent skeletal deformity.  Because of this, it cannot be cured with holistic remedies, and in many cases surgery is necessary.  However, a number of holistic remedies are believed to substantially reduce the pain and suffering caused by elbow dysplasia.  Many of these treatments may help postpone surgery, perhaps even indefinitely.  Because many holistic remedies may interact with conventional medications, always discuss any which are being considered with a veterinarian before use.  Most of the holistic remedies prescribed for elbow dysplasia are thought to act as anti-inflammatories or pain killers.  Among the most commonly suggested are S-Adenosyl-L-methione (SAMe, Denosyl SD4), omega-3 fatty acids, Rosemary (Rosmarinus officinalus), and Meadow Sweet (Filipendula ulmaria).  There are also some treatments which are believed to help strengthen cartilage and even increase the speed which the body replaces it.  Serna mussels (Perna canaliculus), avocado, soybean, glucosamine, chondroitin, Duralactin, and the sulfurous compound methyl-sulfonyl methane (MSM), are some of the treatments are thought to help cartilage.  Massage and acupuncture are also used to help reduce the pain caused by elbow dysplasia.

 

 

PREVENTION & HELPFUL TIPS: 

 

Because elbow dysplasia is an inherent part of a dog’s genetic code since the time it is conceived, it is impossible to prevent the condition entirely.  The one exception to this is the case of elbow dysplasia which has been caused by an injury, which can be prevented by preventing the injury.  Although owners usually cannot prevent elbow dysplasia from developing, they can help prevent the worst of its symptoms.

 

One of the most important things owners can do is to keep their dogs’ weight at a healthy level.  This can be achieved through proper diet and exercise.  Dogs with elbow dysplasia may take more effort to exercise than normal dogs because their joints are very sensitive, so owners should experiment with low impact exercise such as swimming.

 

It is possible to make many changes to a dog’s home and lifestyle that will cause it to put as little strain on its joints as possible.  For example, small ramps can be placed so that a dog neither has to use stairs nor has to jump up in to beds, cars, sofas, and etcetera.  Another example would be placing a dog’s food bowls right next to its bed so that it doesn’t have to walk across the house to get to the kitchen.

 

One of the best ways that owners can help improve their dog’s prognosis is vigilance and early diagnosis.  The younger a dog is when it is diagnosed with elbow dysplasia, the more treatment options it will have and the more likely those options are to be successful.  Early treatment can prevent elbow dysplasia from progressing into a more serious state and can also prevent potential complications from developing across the entire body.  Perhaps most importantly, the earlier a dog is treated for elbow dysplasia, the less pain that it will have to endure.

 

The best way to prevent future cases of elbow dysplasia is through improved breeding practices.  The exact inheritance mechanisms of elbow dysplasia are not yet fully understood because they are polygenic.  Several different genes working together in very complex ways cause elbow dysplasia, and it has so far proved impossible to find sort it out entirely.  However, it is nearly universally agreed that there is a very strong correlation between inheritance and elbow dysplasia.  Any dog which has been diagnosed with elbow dysplasia (unless it was caused by an accident) should not be bred, nor should any parent, sibling, or offspring of a diagnosed dog.  The Orthopedic Foundation for Animals (OFA) keeps records of dogs which have been diagnosed with elbow dysplasia as well as providing other resources for breeders, owners, and fanciers.