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Canine Hip Dysplasia (CHD)

Canine Hip Dysplasia (CHD) affects millions of dogs each year and can result in a debilitating disease of the hip. This article was written for puppy buyers, breeders, and dog owners.

 

 

Table of Contents

What is Canine Hip Dysplasia?

Clinical Signs

Hip Joint of a Normal Dog

Development of CHD

Arthritis and Degenerative Joint Disease (DJD)

Environmental Factors

Diagnosis

Non Surgical Treatment

When to Consider Surgery

Types of Surgery

Genetic Factors and Breeding

Registry

 

 

What is Canine Hip Dysplasia?

Dysplasia come from the Greek words dys, meaning disordered or abnormal, and plassein meaning to form. Canine Hip Dysplasia (CHD) is an abnormality or malformation in the development of the hip joint, which is characterized by the Cup of the hip joint (acetabulum) and the ball of the hip joint (femoral head). These abnormalities may occur due to excessive laxity in the hip joint. The highest incidence occurs in larger, rapidly growing dogs like the APBT and AST. CHD may or may not be bilateral (affecting both the right and left hip joints). It is a relatively common disorder in veterinary medicine. The general veterinary consensus is that CHD is hip joint laxity resulting in Osteoarthritis. Arthritis can develop as a result of the malformation of the hip joint and this results in pain as the disease progresses. Many people have misconceptions about CHD, considering it to be a form of arthritis affecting the hip joints. It is true that you will see severe arthritis in dogs with this condition but this is the secondary result of CHD, not the primary problem.

 

 

Clinical Signs

CHD can exist with or without clinical signs. If an APBT or AST exhibits clinical signs they usually are severely dysplastic on one or both of the rear limbs. Some clinical signs are lameness, difficulty standing or walking after getting up, reluctance or inability to go up or down stairs, decreased activity, a bunny-hop gait, painful reaction to extension of the rear legs, resisting to jump, stiffness early in the morning that improves as the dog warms up, changes in disposition due to pain, wobbly gait, or a clicking sound when walking. Pushing on the rump may cause the pelvis to drop on dogs with CHD. When rolled over, some affected dogs will resist having their legs spread into a frog-leg position. It is also common to see a side to side sway of the body or an increased intertrochanteric width (points of hips are wider than normal). Many dogs with CHD will shift their center of gravity forward in an effort to relieve weight and pressure on the hips. These dogs generally present a front end that appears well developed relative to the rear end. Also, dogs with CHD have a weak hip joint and are more subject to being injured by normal activity such as jumping off a couch, or rough housing with a playmate. It is very important to understand that the only way to accurately diagnose CHD is through X-rays. The above symptoms may also be seen in dogs with normal hips and affected dogs may display none of these symptoms at all.

 

 

Hip Joint of a Normal Dog

In order to understand the development of CHD, it may help to understand the structure of the hip on a normal dog (a dog free from CHD). A ball and socket joint forms the attachment of the hind leg to the body. The ball portion is the head of the femur (the long bone between hip and knee). The socket is called the acetabulum and is located on the pelvic bone. These two form the joint of a normal dog where the ball rotates freely within the socket. The bones are shaped perfectly to match each other with the socket surrounding the ball, which aids in movement. The two bones are held together by a ligament going directly from the femoral head and attaching to the acetabulum, to strengthen the joint. A joint capsule is a thick band of connective tissue that holds the bones together and completely encircles the joint. 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 the normal dog, all of these factors work together for smooth and stable joint function.

 

 

Development of CHD

CHD is a disease that affects the development of the hip joint in a young dog, which is very common in APBT and AST. Even dysplastic dogs are born with normal hips but the soft tissues that surround the joint start to develop abnormally as the puppy grows. The result of the change is that the two bones are not held in place but move apart. The joint capsule and the ligament between the two bones stretch, adding further instability to the joint. As this happens the articular surfaces of the two bones lose contact with each other. The slight separation of the two bones of the joint is called Subluxation, which causes all of the resulting problems we associate with this disease. It is important to remember that if two bones within any joint lose their normal position in relationship to each other, their articular surfaces no longer will correctly contact each other. The surrounding muscles of the dog’s joint work to force the bones back together but they are never totally successful. Because of the dog’s weight, the femoral head often rides up onto or over the rim of the socket. With every movement of the leg, there are now two abnormal areas of bone grinding against each other instead of contacting on a smooth surface. Wherever these bones come in contact, new abnormally shaped bone will grow. New bone growth causes further irritation which causes more abnormal bone growth. This is what we refer to as arthritis and it is usually a very painful condition. The femoral head that once looked smooth now looks like cauliflower. The acetabulum or socket that was once deep enough to enclose the femoral head is now shallow due to the grinding away of the rim. The edge is covered with bone spurs. As the condition progresses, more new abnormal bone forms and along with it comes further pain and distortion of the bone.

 

 

Arthritis and Degenerative Joint Disease (DJD)

Dogs with CHD commonly have osteoarthritis or degenerative joint disease. Abnormal development of the hip causes excessive wear of the joint cartilage, which eventually leads to the development of arthritis, often called degenerative joint disease (DJD) or osteoarthritis. The terms DJD, arthritis and osteoarthritis are commonly used interchangeably when referring to CHD. Most dogs with CHD will develop DJD or arthritis. If your APBT or AST is showing clinical signs of CHD it may very likely also be suffering from DJD. Joint disease in the dog often starts with injury to the cartilage. This can be a result of the joints fitting too loosely, allowing the bones to bump together repeatedly. Because cartilage has no nerves to warn of injury, the dog feels no pain and continues to be active. This accelerates the damage. In response, damaged joint tissues releases enzymes that erode the cartilage and break down the thick, lubrication synovial fluid into a watery liquid, destroying its lubricating quality and reducing cartilage nutrition at a time when it is desperately needed. The initial injury expands, more enzymes are released, and a cycle of joint degeneration is under way. It is not until the damage reaches the joint capsule or subchondral bone, where sensory nerves are located, that signs of pain appear. By then, considerable damage has already occurred.

 

 

Environmental Factors

CHD is not caused by any environmental factors, but environment can influence the expression of the disease. Environmental Factors can determine when and perhaps if, the dog begins to develop symptoms. Some common environmental factors which have been believed to worsen, but not cause laxity in the hip joint (or CHD) are rough pay, jumping or climbing stairs or slick floors, calcium supplementation (may increase the bone remodeling), forced running for any distance especially on asphalt or other hard surfaces, excess weight gain or rapid growth and type of food feed to puppies. It’s best to keep your puppy from any kind of jumping for the first year or so in life. It is very common to see an APBT or AST owner working and exercising their dog at a very young age. But, even for dogs not at risk from CHD, it’s wise not to exercise too strongly too early. Early exercise may interfere with proper growth of joints, leading to CHD or other similar problems in the joint. Dogs with CHD appear to be born with normal hips and develop the disease later. This has led to speculation as to the contributing factors, which may be involved with the disease. But, it is very important to know that dogs without a genetic predisposition for CHD will not develop CHD. Only by genetic selection will the incidence be reduced. In the meantime, it makes sense to have lean puppies, not to exercise (or work) young dogs, feed quality food, and to avoid breeding animals from litters that showed signs of CHD.

 

 

Diagnosis

Only with x rays can we truly diagnose CHD and hope to eliminate it. You can never be positive that a dog showing rear leg lameness has CHD unless it is x-rayed. And you can never be sure that a dog showing no signs is disease-free, without a x-ray you can be fooled either way. CHD can not be diagnosed by observing how the dog moves, acts, lies down, etc. The clinical signs may be caused by other problems; therefore, a complete orthopedic and radiographic examination is required before arriving at the conclusion that the signs are caused by CHD.

 

 

There are a few techniques currently used to detect CHD. The standard and most common view used is Orthopedic Foundation for Animals (OFA) testing. The cost is around $80-$100. OFA is the most well known registry in the United States. It grades all joints, most commonly hips, as severe, moderate, fair, good, or excellent. It will certify all passing grades given to dogs over 2 years of age. The argument with OFA is that the hip-extended protocol followed by OFA may produce false results.

 

 

X-rays utilizing a device to exaggerate joint laxity is developed by the University of Pennsylvania Hip Improvement Program (PennHIP). The cost is around $150. The PennHIP radiographs are more scientifically calculated. The protocol followed by PennHIP has a prognostic capacity through the use of statistics and a database that allows a prediction to be made with respect to the breed and the probability of phenotypic expression of CHD. PennHIP is a new evaluation technique that flexes the limbs differently to produce the x-ray pictures. The problem with PennHIP is that there are only a handful of vets around the country that have been certified to take x-rays using the method.

 

 

Genetic Disease Control (GDC) at UC Davis has a program for radiographic evaluation of dogs. They have programs offered to Labrador Retrievers, Rottweilers, and a few other breeds (not yet for the APBT or AST). GDC will certify a dog at one year of age or older and requires x-rays of hips, elbows, and hocks. GDC is actually a larger effort to collect data on all kinds of genetic diseases, in which CHD is only one. For more information you can write to GDC at PO Box 222, Davis CA 95617 or call 916-756-6773.

 

 

Outside of the United States each country has its own hip evaluation program. These are not consistent from country to country and may differ with the evaluation given above. In Australia, the Australian Veterinary Association that has an Australian wide scoring system that evaluates dogs by using averages for each breed.

 

 

It is believed that unless some effort is made to publish the results of diagnostics test openly we may not ever be able to eliminate CHD. This is the only way that breeders will be able to tell for certain what the problems have been with CHD in a dog’s ancestry. CHD can be difficult to diagnose a number of other orthopedic, neurological, autoimmune and metabolic problems may mimic it. Degenerative Myelopathy, a neurologic condition that is common in German Shepherds, is often confused with progression of CHD. CHD is one of the most over diagnosed and misdiagnosed conditions. It is important to know that diagnosis of CHD is not an automatic death sentence for your dog. Some dogs may experience little or no discomfort and you may never know they have CHD unless you test for it.

 

 

Non Surgical Treatment

The good news about CHD is that most dogs can be treated to help eliminate or decrease pain, allowing fairly normal levels of activity. Very few APBT or AST have to be put to sleep to alleviate suffering. There are always choices to be made, but the majority of affected animals can live comfortable lives. APBT and AST are known for having an incredible pain tolerance, and normally do not need a surgical procedure to elevate pain. Dogs that exhibit clinical signs after growth phase may require a different approach to treatment. Every dog is different in its response to pain and the treatment protocol needs to be tailored specifically to the particular animal.

 

 

1. Treatment for Young dogs- in the young suddenly showing discomfort, treatment is usually combined with rest. It is not unusual for pain to appear and disappear for several years and then to return when arthritic changes become obvious. For dogs that exhibit clinical signs at less than a year of age, aggressive treatment may help alleviate later suffering. Surgical reconstruction of the hip joint is helpful if done during the growth stages. The puppy with CHD usually starts to show signs between five and 13 months old. These range from mild discomfort to extreme pain when using the hind limbs. This will occasionally be seen following prolonged activity or when the dog gets up or lies down. Later in life the signs become more consistent. Signs of CHD in young dogs are generally thought to be from small irritations or even minor fractures occurring in the bone spurs that form around the socket. The pup’s increasing weight or exercise may cause fractures. Sudden periods of discomfort are usually followed by prolonged activity. Buffered Aspirin combined with cage rest for five to seven days is usually adequate to put out the fire until the next flare-up. As the dog matures, surgery is the solutions of outward signs of discomfort are consistent. Although a few dogs can be maintained for long periods, with pain medication and anti-inflammatory drugs, this is usually not the answer.

 

 

2. It is possible to help dogs dramatically through medication. It is also important to use appropriate dosages and to monitor the progress of any dog on medications due to the increased risk of side effects. If medical treatment is insufficient then surgical repair is possible. Non surgical treatment should always be considered first to attempt to improve function and reduce pain and inflammation. All medications you give your dog should be under the supervision of a veterinarian.

 

Some medication used:

 

* Buffered Aspirin is probably the best choice for initial medical treatment. It is a safe and useful drug, although prolonged use can cause problems. But, for occasional use, aspirin is perfectly ok. A large (60 to 70 lb.) dog would get ½ of 5 grain (325 mgm) tablet three times a day, or 1 tablet morning and night.

 

* Aspirin/Codeine combinations * Phenylbutazone

 

* Glycosaminoglycosans- such as Adequan (an injectable drug), Cosequin or Glycoflex (both given orally). Active ingredients usually include glucosamine, chondroitin or perna caniculue, sometimes creatine, and often and assortment of miscellaneous vitamins and minerals. Although their use is not yet supported by sound scientific studies, these products seem to be quite effective. They work best when in the early stages of arthritis, while there is still reasonable joint function left to preserve. A Veterinary formula called Synovicre has also been recommending, which is easier to use than other products and much less expensive.

 

* Corticosteroids may be more beneficial or necessary for some dogs.

 

* NSAIDS (non-steroidal anti-inflammatory have also been recommended)

 

* Steroids

 

* Bute- is a FDA-approved drug for use in dogs, it is effective in elevating pain, but they are not without serious side effects.

 

* Rimadyl- a new non-steroid anti-inflammatory drug that can help considerably in some cases without the typical side effects of traditional steroidal drugs.

 

* EtoGesic is approved for osteoarthritis (1998) in dogs. It is a non-steroidal anti-inflammatory drug and appears to avoid the liver problems sometimes associated with Rimadyl.

 

Both Etogesic and Rimadyl are newly approved drugs that are much more effective than aspirin and for long term use and are considered much safer. They are expensive (about a dollar a day), but make a huge difference in the lives of arthritic dogs. These are prescription drugs, which must be obtained from a veterinarian.

 

 

3. Vitamin therapy can also be effective in reducing inflammation.

 

* Vitamin E supplementation has been reported to help some dogs.

 

* Vitamin C- There is no conclusive evidence that vitamin C can prevent hip dysplasia, but there is some evidence that vitamin C may be useful in reducing pain and inflammation in the dysplastic dog. Fortunately, large doses of vitamin C are readily excreted, but it is still possible to cause inward side effects with megadoses.

 

* Ester-C is a superior form of the Vitamin C. It can be purchased in health food stores. The vitamin in Ester-C is molecularly locked to calcium, so it doesn’t cause the acidity problems normally associated with ascorbic acid (the common form of Vitamin C), which can upset a dog’s stomach. Ester-C also has natural C metabolites that get it into the cells faster and more effectively. Ester C helps to sort of lubricate the joint so the dog feels less pain. It has been shown that 75 percent of dogs given Ester-C had improvement rate in various degrees in a short period time. Soft tissue-cartilage and synovial membrane exist between bones to permit movement. If such tissue deteriorates, movement becomes more painful. Vitamin C is essential in the making and rebuilding of soft tissue because it promotes the growth of Collagen, a tough, stringy “mortar” that holds water, which maintains compression resistance to cushion the joint (this, is the lubrication). Under diseased or inflammatory conditions, cell loss is excessive. In the case of a dog’s hip joint, this can mean that adequate cushioning no longer exists. The high demand for Vitamin C may begin exceeding the amount made in the dog’s liver, so deterioration continues. Or supplemented Vitamin C (or ester-C) may turn the process around. Yet, some doctors believe that the treatment is merely a Band-Aid on a far more serious problem.

 

* Stay away from calcium supplementation of any kind all it can do is hurt.

 

 

4. Weight loss can have a dramatic effect on the amount of discomfort a dog experiences. Older large breed dogs often tend to be overweight. It is not uncommon to see an overweight APBT or AST. This discourages them from getting the exercise they need and aggravates their arthritis. The more weight on the poor old joints, the harder it is to move around. Any “light” diet or one intended for older dogs is helpful.

 

 

5. Gentle regular exercise can be very helpful, but exercise restriction is also sometimes recommended. An ideal type of exercise for dysplastic dogs is swimming which allows exercise without stressing the joints. Or, walking once or twice around the block two or three times a week is about right. Avoid strenuous activity on the weekends alternating with little or none during the week.

 

 

6. Simple steps like providing a warm bed or warm spot to rest during the day may help. A soft comfortable place to sleep, your dog’s bed should be as comfortable as your own. An old mattress or soft couch is excellent. Soft foam rubber at least four inches thick is good. Some dogs even have their own waterbeds.

 

 

7. Acupuncture

 

 

8. Chiropractic

 

 

9. Euthanasia- should only be considered when the dog’s pain could not be controlled.

 

 

Working with your vet to come to the best solution for your dog and your situation will enable you and your dog to enjoy life to its fullest, despite the presence of CHD. It is often possible to help dogs in pain from CHD medically or surgically. X-ray confirmation of the presence of CHD prior to treatment is necessary.

 

 

When to Consider Surgery

Several surgical procedures exist to treat CHD. Each procedure has pros and cons associated with it. Different surgeons may have more experience and are more skilled with a particular type of surgery. A second opinion before surgery may be helpful. Surgery is indicated when:

 

* Non-surgical management has failed to reduce pain or restore function.

 

* Medical management has resulted in unacceptable side effects.

 

* Surgery will correct current problems

 

 

Surgery will prevent or slow the progress of further problems Factors that will be considered in selecting a type of surgery to be preformed should include:

 

* Age and weight of the animal

 

* Complicating factors such as extensive bone remodeling or osteoarthritis

 

* Function of the dog (is it a working dog, required to perform strenuous activity or is he primarily a sedentary pet).

 

 

Surgery is a viable option given the suitability of the candidate animal, the financial resources available, the expected activity level, longevity and the use and value of the animal. Choice of intervention, whether medical or surgical, and activity level depend upon the disease process. Problems with certain procedures may be associated with improper selection relative to the stage of the disease or owner post-operative management. It is important remember that CHD, as a degenerative joint disease, is a process, and that different interventions may be required at different stages in the process. Be aware that surgery cannot undo generations of genetic makeup, or prevent that which is predisposed.

 

 

Types of Surgery

1. Triple Pelvic Ostomy (TPO)- is the most often recommended surgical treatment for CHD before advanced remodeling of the joint has taken place. This procedure must be done before the acetabulum has been worn down and therefore is usually recommended for young dogs (less than 9 months of age) who have clinically diagnosed Subluxation and has no damage to the dorsal acetabular rim or any type of early evidence of degeneration on radiographs. The surgery involves cutting the pelvis in three places and then tilting the bone to a more favorable angle to keep the femoral head in place. TPO surgical procedure increases coverage of the femoral head. Increasing coverage promotes improved articulation and, in the ideal situation, joint degeneration is halted. However, if degeneration is already present within the hip, cartilage breakdown is likely to continue, even with improved articulation. This is why checking your dogs at 6-8 months regardless of symptoms is often recommended. Approximate cost $800-$1,200 per hip. After TPO the dog must be kept on crate rest for several weeks to allow the healing process to occur.

 

 

2. Inter-Trochanteric Osteotomy is a somewhat similar option to the inter-trochanteric osteotomy, which changes the length and angle of the femoral head. Both procedures are aimed at improving the fit between femur and acetabulum. Approximate cost for Inter-Trochanteric Osteotomy is $800- $1,000 per hip.

 

 

3. Total Hip Replacement involves replacing the head and neck of the femur and the acetabulum with prosthetics. By removing the damaged acetabulum and femoral head and replacing them with artificial joint components, pain is nearly eliminated. The artificial joint is made of steel and high-impact plastic. Major surgical failure lead directly to a requirement for total hip replacement. And it is considered to be the best surgical treatment for dogs with severe CHD.

 

Indications for this type of surgery are:

 

* Osteoarthritis associated with CHD

 

* Failed head and neck excisions

 

* Irreparable head and neck fractures

 

* Non-reducible chronic hip luxations

 

* Avascular necrosis of the femoral head

 

* And repair of a failed total hip arthroplasty

 

* When all else has failed, especially surgical procedures

 

A dog with arthritic hips and pain-free normal function is not a candidate for total hip replacement. The ideal candidate must have obtained adult growth, usually between 9 to 12 months of age, and must have obtained at least 30 pounds lean weight (which would rule of most APBT and AST). It is quite costly (averaging around $1,500 per hip). In some cases, this surgery may be beyond a pet owner’s financial resources. The prosthesis can be expected to last for the life of the dog and the dog can bear weight very soon after the surgery. Most dogs are able to resume their normal level of activity within two months after surgery. Results are not guaranteed but they tend to be consistently good to excellent, as supported by reports in the medical literature. As with any orthopedic surgery, infection can pose a serious threat to the recovery and usually antibiotics are prescribed. Infection is the most common occurrence associated with hip replacement and is directly related to the number of surgeries and the duration of the procedure. Other contraindications include anemia, neurological disease and concurrent orthopedic problems. Another complication that may occur with this surgery is a condition called cement disease or aseptic loosening. With cement disease, a synovial like membrane containing particulate debris develops that produces large amounts of bone reabsorbing factors. Total hip replacement is not prophylaxis to the problem; it is but a Band-Aid to the underlying genetic problems.

 

 

4. Uncemented Hip Prostheses is a Subcategory of hip replacement surgery. Dr DeYoung of NCSU, professor of orthopedic surgery in the College of Veterinary Medicine, helped develop the prosthesis based on a human version that is held in place without cement. The prosthesis features a beaded surface, into which bone and fibrous tissue can grow and secure the components. More than 100 of the new prostheses have been implanted in dogs over a five-year period without loosening or infection, which are two of the main concerns with cemented total hip replacements.

 

 

5. Femoral Head (and Neck Excision) Ostectomy (FHO) involves removing both the head and neck of the femur. The dog’s muscles are then used to support and cushion the femoral shaft. This eliminates most of the bone to bone contact and can reduce the pain substantially. The standard procedure has the best chance for success in dogs weighing less than 50 lbs. and some clinicians feel that the procedure is most effective for dogs less than 35 lbs. Therefore, the standard procedure may not be recommended for most APBT or AST. A modified procedure for dogs weighing more than 50 lbs. has been developed. This is a great benefit to the APBT and AST owner. The femoral head ostectomy has been modified to include a muscle sling to support and cushion the femoral shaft. The sling is formed from the biceps femoris muscle (biceps muscle of the thigh). Two other options include using a part of the gluteal muscle (buttock muscle) to pad the area between the excised femoral shaft and the pelvis, or using the joint capsule itself to accomplish this. These pads are sewn into place to fix their position. Over time, the muscle pad is transformed to a fibrous mass that is better able to absorb the impact of the forces exerted by the femora. Nothing will replace the near-frictionless and hydrostatic dampening of the cartilage of the original joint when it was in good condition, but if forces are limited, the muscle pad has been shown to serve well in this function in many cases. The dog’s body will compensate as the outer muscles in the area become stronger and hold the leg in place. This allows near-normal motion and use. Once the femoral head and neck have been removed, the surgeon takes the joint through a complete range of motion. This ensures that there are no obstructions to normal articulation. The muscle pad is sewn into place so it will attach securely to the acetabulum. The clinician also checks for crepitus, which is a dry, crackle sound. Ovary crepitus may indicate that not enough of the femoral neck was removed or the boney fragments are still at the excision site. Both conditions would cause loss of function and pain after surgery. It is much better to reduce the problem at the time of surgery than to have a go back into the joint a second time. Only dogs who demonstration severe bony changes in the coxofemoral joint and the clinical signs of pain should be considered for this procedure. This should be considered an end-stage salvage procedure, but cost is usually much lower than other types of surgery. The FHO is sometimes the only affordable surgical option available to many dog owners. Not all dogs do well following FHO surgery and it should be considered a clear second choice. FHO is an alternative surgery to the expensive total hip replacement surgery. While there is significant potential for long-term complications, FHO should be carefully considered within its narrow recommended parameters. A prolonged recovery, muscle atrophy and “bed sore” type ulcers are frequent problems associated with this procedure. In this procedure the bone is shortened, therefore the gait will be affected. The biceps sling can cause a slight adduction (drawing in toward the centerline) of the affected limb during exercise. Obese or very large dogs will experience some pain, as the muscles cannot totally compensate. On the positive side, this procedure has worked well over the years. The dog is pain free afterwards and learns to walk again, but running and jumping are not done normally again. It is radical and invasive surgery, but under the right circumstances has produced very acceptable results.

 

 

6. Shelf Arthroplasty (BOP procedure) seeks to extend the rim of the joint, thus improving stability. Polymer lattices are implanted in the affected joint. The premise is that new bone will grow over the lattice, correcting the degeneration and deformation of the joint. This procedure is designed for a dog that already has extensive damage to the joint. This option has been criticized because it does not halt the progression of arthritic changes; thus the animal may continue to have worsening pain. This is a relatively experimental method, whose effectiveness is debated.

 

 

7. The final Surgery involves cutting of the pectinious, which is one of the muscles that try to add stability to the joint by forcing the two bones back together. When it is cut or has a portion removed the two bones move apart. It sometimes eliminates all pain and further surgery is not required.

 

 

Genetic Factors and Breeding

“The condition described herein, rare though it may be, should be recognized as being congenital and potentially hereditary, and the dog or bitch in which it occurs should be destroyed or sterilized in the eugenic interests of the breed.” This quote came from a paper entitled Bilateral Congenital Subluxation of the Coxofemoral Joints of a Dog by Schnelle. CHD is one of the most baffling diseases affecting dogs today. We know this is an inherited disease, but identifying the hip dysplasia gene is difficult because this seems to be a polygenic disorder, with several different genes responsible. These genes may also be masked or hidden genes that are not expressed in several generations until the disease turns up again in the progeny. That’s why there is such a low level of confidence when breeders say, “There is no background of hip dysplasia in my dogs lines”. If you are an APBT or AST breeder, you should know that there is a slim chance that CHD isn’t in your dogs lines. Conscientious dog breeders are anxious for a genetic screening procedure that would help eliminate CHD. CHD is genetically spread from one generation of dog to the next. A veterinarian can certify that a dog is not dysplastic by having it x-rayed. By breeding only those dogs free of Dysplasia, we continue our efforts to eliminate the disease. If you are not x-raying your breeding animals you may contribute to the problem rather than the solution. CHD traits do not follow patterns based on dominant/recessive pairs. Without the genes necessary to transmit this degenerative disease, there is no disease. This is not something a dog gets, it is either genetically dyplastic or it is not. An affected animal can exhibit a wide range of phenotypes, all the way from normal to severely dysplastic and functionally crippled. There is no substitute for genetic screening and refraining from breeding, no matter how attractive a particular breeding might be unless there is a clear indication that the parents, their siblings and get are free from CHD. Guidelines recommended to decrease the incidence of CHD in a breeding program are breed normal to normal, breed normal with normal ancestry, breed normal from litters with low incidence of CHD, select sire that produces a low incidence of CHD. Using the word normal to refer to a dog free from CHD. When purchasing a puppy it is wise to look at the hip clearances of not only the parents, but the brothers and sisters, grandparents and other offspring of the parents. Having mostly clear relatives on both sides is thought to increase the chances of the litter having clear hips. Prospective buyers should check pedigrees and verify health issues with the breeder. If suitable documentation is not available, assume the worst until proven otherwise. If you suspect your dog may have dysplastic hips or you are planning to breed, arrange for a x-ray to be taken. If CHD is diagnosed YOUR PET SHOULD BE SPAYED OR NEUTERED! You should also notify the breeder of your dog so that they can use that information to take steps to improve the breeding program that produced the problem. Only some puppies will have the same combination of genes for a trait as the parents. Some will have a more desirable combination while others will have a less desirable pattern. Remember that it is also possible for different genes to have a different level of influence on the trait, complicating the outcomes considerably. Predictions of a specific outcome from a particular mating involving polygenic traits are currently impossible. A dog with excellent hips but with more than 25 % of its brothers and sisters affected with CHD is a poorer breeding prospect than a dog with fair hips and less than 25% of its brothers and sisters exhibiting CHD. There is no known method of preventing CHD except for a thoughtful and carefully executed breeding program with regular radiographic analysis of all stock before breeding. It is possible to reduce symptoms entirely to the point where the dog will radiograph much less severely, however follow-up studies show that these dog’s offspring have the same risk for CHD as they would have whether the parents had been so treated. The implication is that it is unethical to use as breeding stock dogs that were treated to prevent their symptoms from disappearing. Unfortunately, the absences of CHD in canine parents does not guarantee dysplasia free pups. Out of 100 breedings of normal dogs in breeds affected by CHD (which include the APBT and AST), only 75 percent of puppies will be normal and 25 percent, on average, will have CHD.

 

 

Registry

Sadly, no breed registry in the United States requires genetic screening of parents as a prerequisite for litter registration or even offers a fitness for breeding certification. The current registries for CHD (and other genetically transmitted problems) cover so little of the registered dog population that their impact has been minimal. The tools we need are there. Joint responsibility for failing to use the tools at hand lies with the individual breeders along with the breed registries. Until the time that the genetic disease aspect is recognized and successfully handled, there will be a continued necessity for the surgical option.