Hip Dysplasia Treatment and Information
Interview with Dr. Tobin, DVM
Dr. Stephen Tobin is a holistic veterinarian who providestreatment using homeopathic herbs and nutrition. He speaks with us about hisphilosophy of animal care, pet nutrition, and his experience with the LonglifeProgram in the treatment of his patients.
How Does Longlife Treat Hip Dysplasia?
Longlife for Dogs contains pure shark cartilage, specially processed for maximum absorption intothe bloodstream by your dog's digestive system. It contains Amino Acids and HighProteins, with natural Mucopolysaccharides, which promote the generation of newcartilage cells - a major factor in stiffness and inflammation associated withover-exertion or arthritic joints.
Understanding the Canine Hip Joint
To understand what hip dysplasia really is, one must start with an understandingof the hip joint. The hip joint forms the attachment of the hind leg to the bodyby way of a “ball and socket.” The ball portion is the head of the femur (thelong bone extending from the hip to the knee), while the socket (known as theacetabulum) is located on the pelvis. In a normal joint, the ball rotates freely,and snugly, within the socket. To facilitate movement, the bones are shaped tomatch each other perfectly, with the socket surrounding the ball. The two bonesare held together by a ligament, which strengthens the joint, and attaches thefemoral head directly to the acetabulum. The joint capsule, which is a very strongband of connective tissue, encircles the two bones and adds further stability.The area where the bones actually touch each other, the articular surface, isperfectly smooth and cushioned with a layer of spongy cartilage. In the normaldog, all of these factors work together to facilitate smooth movement and stability.
A good hip joint has a neat, snug fit between the ball and socket; the headof the femur should not be riding around somewhere in the neighborhood of theacetabulum. CHD occurs when the hip joint loosens. Most of the problems resultingfrom hip dysplasia are a result of this looseness: a loss of tension in the muscles,connective tissue, and ligaments that should support the joint. Most dysplasticdogs are born with normal hips, but due to genetic and possibly other factors,the soft tissues that surround the joint start to develop abnormally as the puppygrows. The most significant of these changes is that the bones are not held inplace but actually move apart. The joint capsule and the ligament between thetwo bones stretch, adding further instability to the joint. As this occurs, thearticular surfaces of the two bones lose contact with each other. This separationof the two bones within a joint, called subluxation, causes all the resultingproblems we associate with the disease.
There are infinite variations of dysplasia, ranging from only very slightdysfunction to complete dislocation. Consequently, no two dogs will be affectedby CHD in exactly the same way.
Risk Factors for Hip Dysplasia
The basis for CHD is the dog’s genetic makeup, which can be measured by whatis termed the Heritability Factor. Heritability is measured on a scale from zeroto one, with a condition totally unrelated to genetics (such as a traumatic injury)measured at zero and a condition entirely determined by genetics (such as gender)measured at one. Studies have shown that CHD's Heritability factor ranges from.25 to .85, which indicates a significant genetic contribution. Therefore, ifthe parents are carrying genetic material for CHD, the offspring is guaranteedat least to carry the gene. And the greater the Heritability Factor for loosehips or malformed bone or abnormal muscle mass from the parents, the greaterthe chances for hip dysplasia in the offspring.
The expression of hip dysplasia in any dog has other determinants, though;genetics are only one factor in the total picture. The effect of the developingdog's environment does play a role in the observable signs of dysplasia, althoughjust as with the genetic component, the effects of environment are variable andnot completely understood. In other words, it is possible for a dog with knowngenetic components for hip dysplasia not to show any clinical signs of troubleif the environmental factors are favorable, or not to show observable signs ofit until middle or old age.
Genetic CHD factors in dogs are distributed unevenly across certain breeds.CHD is primarily a disease of large and giant breeds, though it can occur inmedium-sized breeds and rarely in small breeds. It primarily afflicts purebreds,although it can happen in mixed breeds, particularly a cross of two dogs thatare prone to developing the disease. German Shepherds, Labrador Retrievers, Rottweilers,Great Danes, Golden Retrievers, and Saint Bernards appear to have a higher incidence,but these are all very popular breeds and may be over-represented because oftheir popularity. Other high-risk breeds include the: American Bulldog, AmericanStaffordshire Terrier, Beagle, Bernese Mountain Dog, Bloodhound, Bouvier desflandres, Boykin Spaniel, Briard, Brittany, Bulldog, Bullmastiff, ChesapeakeBay Retriever, Chow Chow, Clumber Spaniel, Coonhound (Black and Tan), Coton deTulèar, Curly Coated Retriever, English Setter, English Springer Spaniel, GiantSchnauzer, Gordon Setter, Irish Water Spaniel, Kuvasz, Neapolitan Mastiff, Newfoundland,Norwegian Elkhound, Old English Sheepdog, Otterhund, Polish Lowland Sheepdog,Portuguese Water Dog, Pudel Pointer, Pug, Rottweiler, Shih Tzu, Spanish WaterDog, Staffordshire Terrier, Sussex Spaniel, Welsh Corgi, and Welsh Springer Spaniel.Greyhounds and Borzois have a very low incidence of the disease.
Formula for Determing a Dog's Predisposition to CHD
The formula for determining any dog's predisposition to CHD is complex, takinginto account not only genetics and breed but a whole host of contributing factors.It must be stated that some researchers believe that genetics is the only factorinvolved, whereas others think genetics contributes less than 25% to the developmentof the disease. The truth probably lies in the middle. If there are no geneticcarriers of hip dysplasia in a dog's lineage, then it will not contract the disease.If there are genetic carriers, then it may contract the disease. The incidenceof hip dysplasia can be greatly reduced through a certain type of selective breeding,as well as increased. However, the disease cannot be completely avoided throughselective breeding. In other words, if two dysplastic dogs are bred, the offspringare much more likely to develop the disease, but will not all have the same levelof symptoms, or even necessarily show any symptoms. The offspring from thesedogs will, however, be carriers and the disease may show up in their offspringin later generations. This is why it can be difficult to eradicate the diseasefrom a breed or specific line, or even to produce the conditions under whichthe disease would be guaranteed to occur. The following factors affect a dogto varying degrees:
Nutrition: A key contributor to CHD is obesity. The effortof carrying extra weight will exacerbate degeneration of the joint in a dog witha loose hip. Overweight dogs are therefore at a much higher risk. Another factorthat might increase the incidence is rapid growth in a puppy during the agesfrom three to ten months. Experimentally, the incidence has been increased ingenetically susceptible dogs when they are given large-quantity/large-caloriediets. A 1997 study showed that Labrador Retriever puppies that were fed a high-protein,high-calorie diet free choice for three years had a much higher incidence ofhip dysplasia than their littermates who were fed the same high-calorie, high-proteindiet, but in an amount that was 25% less than what was fed to the dysplasticgroup. As might be expected, however, the free choice group was significantlyheavier at maturity, averaging 22 pounds heavier than the control group.
There have also been studies examining protein and calcium levels and theirrelationship to hip dysplasia. These studies found that increased amounts ofcalcium and protein in the diet were correlated with a higher incidence of hipdysplasia. But once again, these studies compared puppies fed greatly increasedamounts over normal recommended values to animals fed decreased amounts. Theyfailed to compare puppies fed a normal amount of food that had the recommendedamount of protein, fat, and calcium to those fed a diet with slightly less protein,fat, and calcium (similar to those “large breed puppy foods” that are now floodingthe market). No studies link an increased incidence in hip dysplasia in dogsfed a normal diet of commercial puppy food versus a specialty diet formulatedjust for large breed puppies.
Some reports indicate that in puppies a restricted calorie intake could restrictthe growth rate, and in turn lessen the likelihood of the dog developing hipdysplasia. The problem with this is that some restricted diets restrict the fatand protein content and increase the carbohydrate content of the food. A petowner’s real goal should be to keep growing pups from becoming overweight. Restrictingfat and protein in a growing pup can be a disaster. A high-quality, meat-baseddiet is absolutely necessary for growing pups, as long as the owner does notfeed the puppy so much that it becomes overweight.
Exercise: A young, growing dog with a genetic makeup forCHD will be more likely to develop arthritis and have more difficulty in thelong term if it is highly active physically. Climbing stairs, jumping, and runningcan all subject the growing hip structures to unwarranted stress and trauma andincrease the risk of future discomfort for the dog. The effects of excessiveactivity are worsened in an overweight pup. (In a normal, growing dog, theseactivities will not cause hip dysplasia.)
In short, it appears that dogs that are genetically susceptible to the diseasemay have an increased incidence of disease if they over-exercised at a youngage. At the same time, we know that dogs with large and prominent leg musclemass are less likely to contract the disease than dogs with small muscle mass.So, exercising and maintaining good muscle mass may actually decrease the incidenceof the disease. Moderate exercise that strengthens the rump, or gluteal muscles,such as running and swimming, is probably a good idea, whereas activities thatapply a lot of force to the joint, such as jumping during a game of Frisbee,are contraindicated.
The Pectineus Muscle can contribute to the worsening of hipdysplasia. In a dog with a strong genetic background for CHD, the microscopicmakeup and contractibility of the Pectineus Muscle are strikingly different fromthe corresponding muscle of a normal dog. The theory is that a tight or inelasticPectineus Muscle causes tension in such a way that the force tends to pull thehead of the femur away from the acetabulum, increasing looseness in the joint.I have had good results in about 50% of the cases in which I have surgicallyexcised a portion of the Pectineus Muscle. The patients were more comfortableand mobile almost immediately. This Pectineal Myotomy surgery has no effect onthe arthritic changes in the hip joints, but it can make the dog more comfortable.
Surfaces: There is no scientific proof that surfaces havean impact on the disease, but many observers conclude that pups reared, especiallyduring the nursing period, on slippery surfaces such as newspapers will be proneto hip difficulties. Smooth concrete or wood surfaces may not cause dysplasia,but they can make a bad situation worse. Better surfaces for newborn pups areblankets or towels—surfaces they can grip.
Symptoms of Hip Dysplasia
The symptoms of CHD can be the same as those often found in many other ailments:hip soreness, difficulty arising or climbing inclines, and limping. However,a few very specific symptoms can be signs of CHD:
Bunny Hopping: The dog tends to use both hind legs together,rather than one at a time. This occurs when the dog is running or going up stairs.
Side Sit: Also called lazy sit, slouch, or frog sit. Whenthe dog sits, its legs are not positioned bent and close to the body. They canbe loose and off to one side, or one or both legs may be straight out in front.
Sway Walk: Also called a loose walk. When the dog is walking,the back end sways back and forth because the hips are loose. The dog seems tobe tiptoeing or walking very lightly on its rear legs. A dysplastic dog willbe reluctant to jump or "stand up" on its hind legs.
Unusual Lying Position:Legs are straight out and off to theside when the dog is lying on its stomach or legs are straight out behind thedog. (All dogs lie with their legs behind them on occasion, but many dogs withhip dysplasia lie like this all the time.)
Limping: The dog may favor one hind leg or the other, andmay alternate legs that it is favoring.
Doesn’t Jump: Not only does the dog not jump on you, it seems to pull itselfup by its front end onto furniture instead of jumping up.
Underdeveloped Hind Quarters and Overdeveloped Chest: Thisis caused by the failure to use the hind legs normally and jump. The dog alsomay actually be shifting weight forward.
Occasionally the symptoms break down by age:
Symptoms in young dogs: Puppies who are already in pain fromhip CHD tend to be very good puppies. They do not roughhouse the way that normalpuppies do, and they tend to sleep for a long time after playing or going fora walk. Some owners describe their puppy as the best puppy they’ve ever had.The second warning sign is a puppy that runs with both back legs nearly together,almost as a bunny hop (see above). After exercise the puppy might be reluctantto rise, will sit back as if unsteady, and (this will be most apparent) willhave difficulty climbing stairs or inclines. The puppy might look slightly underdevelopedin the rear quarters. When it stands the rear legs may not be parallel, but rathertoo close together at the ankles. This is a condition called "cow hocked." Anowner might notice a boniness to the pelvic area from lack of good muscle development.Another hint of trouble is an inability to extend the leg backward very far (decreasedrange of motion).
Signs usually become evident between five and eights months of age. But remember,as we learned above, some dogs do not show any signs at all of hip joint degenerationuntil adulthood.
Symptoms in breeding dogs: Those looking to breed their dogs(especially for competition) should have an X-ray in all circumstances. In onetest case, a Golden Retriever had absolutely no outward symptoms. He jumped andswam and had never shown any kind of lameness. In preparation for breeding, theowner had the dog X-rayed, and the X-ray displayed severe abnormalities in theleft hip joint. Were the changes due to a genetic propensity for hip joint abnormalities,or was this actually due to an injury early in the pup's life that impacted theproper growth of the joint structures? No one can say for certain. But if theabnormal hip was due to genetic determiners, why take a chance of the litterhaving even worse hip joint conformation? (Note: The owner decided not to breedthe dog.)
Signs of CHD in older dogs: Some dogs with dysplasia escapepain or simply accept it as a fact of life—at least for the first few phasesof life. In fact, they don't complain until degenerative joint disease sets in.Affected older dogs will sit rather than stand, have trouble arising, run withthe rear legs together, and be unable to keep up speed on walks. Every veterinarianhas been mystified, from time to time, when an X-ray of an older dog who onlyrecently seemed to be having hip trouble revealed extensive degenerative changesin the hips due to long-term dysplasia.
It is very important to keep this fact in mind: A dog can appear normal andyet have hip dysplasia. Just because a four-year-old dog isn't showing signsof trouble does not mean it doesn’t have hip dysplasia or won’t in the future.
Hip dysplasia diagnosis
Diagnosis of hip dysplasia in dogs is usually made by a veterinarian througha combination of a physical exam and X-rays. The veterinarian may even be ableto feel looseness in the joint or may be able to elicit pain through extensionand flexion. Regardless, the results are straightforward and usually not difficultto interpret.
However, about half of the animals that come in for a determination on thehealth of their hip joints are not showing physical signs, but are intended tobe bred. The breeder wants to ensure that the animal is not at great risk fortransmitting the disease to his or her offspring.
Hip Dysplasia Testing Methods
There are two different testing methods that can be performed: the older OFAtesting and the newer Penn HIP method.
OFA: The method used by the Orthopedic Foundation for Animals(OFA) has been the standard for many years. The OFA maintains a database of hipevaluations for almost half a million dogs. Radiographs are taken by a localveterinarian under specific guidelines and are then submitted to the OFA forevaluation of hip dysplasia and certification of hip status. Since the accuracyof a dog’s diagnosis of hip dysplasia using the OFA technique increases after24 months of age, the OFA requires that the dog be at least two years of ageat the time the radiographs are taken. They also recommend that the evaluationnot be performed while the female is in heat. To get the correct presentationand ensure that the muscles are relaxed, the OFA recommends that the dog be anesthetizedfor the radiographs. OFA radiologists evaluate the hip joints for congruity,subluxation, the condition of the acetabular margins, and acetabular notch, andthe size, shape, and architecture of the femoral head and neck. The radiographsare reviewed by three radiologists and a consensus score is assigned based onthe animal's hip conformation relative to other individuals of the same breedand age. Using a seven-point scoring system, hips are scored as normal (excellent,good, fair), borderline dysplastic, or dysplastic (mild, moderate, severe).
PennHIP: The diagnostic method used by the University ofPennsylvania Hip Improvement Program (PennHIP) uses distraction/compression radiographicviews to more accurately identify joint laxity. Radiographs of the hip jointsare taken with the dog under heavy sedation. Two views are obtained with thehind limbs in neutral position; this maximizes joint laxity. Weights and/or otherdevices are used to help push the head of the femur further into or away fromthe acetabulum. The amount of femoral head displacement (hip joint laxity) isquantified using a distraction index (DI). The DI ranges from 0 to 1. It is calculatedby measuring the distance the center of the femoral head moves laterally fromthe 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 luxationwith little or no coverage of the femoral head. A hip with a distraction indexof .6 is 60% luxated and is twice as lax as a hip with a DI of .3. When the DIwas compared to the OFA scores for 65 dogs, all dogs scored as mildly, moderately,or severely dysplasticby the OFA method and had a DI above .3.
Hip joint laxity as measured by the DI is strongly correlated with the futuredevelopment of osteoarthritis. Hips with a low DI are less likely to developosteoarthritis. Hips with a DI below .3 rarely develop osteoarthritis visibleon radiographs. Although hips with a DI above .3 are considered "degenerativejoint disease susceptible," not all hips with a DI greater than .3 eventuallydevelop osteoarthritis. It is known that some hips with radiographically apparentlaxity do not develop osteoarthritis. A means of differentiating lax hips thatdevelop osteoarthritis from those that do not is important in developing a prognosisand making treatment recommendations. In one study, the DI obtained from dogsat four months of age was a good predictor of later osteoarthritis, though the6- and 12-month indices were more accurate.
To assure quality and repeatability among diagnostic centers using PennHIP,veterinarians must take a special course and become certified. As this techniquegains popularity, more veterinarians are becoming certified.
Anesthesia: During the diagnosis, anesthesia is necessary.To yield an X-ray with the information the owner is trying to discover, the dogmust be perfectly relaxed. Because the position required to take a diagnosticX-ray is unnatural, even very gentle, cooperative dogs cannot relax enough tobe X-rayed properly. It is frustrating for the veterinarian for an owner to claimthat anesthesia is not necessary, that the dog will “do anything you tell itto.” Unless at the time of exposure of the X-ray the dog is positioned precisely,with no movement, the X-ray will not be credible.
Another great advantage of anesthesia is that it allows the veterinarianto palpate and manipulate the hips to actually feel the degree of looseness.Also, the tension of the Pectineus Muscle is best assessed under anesthesia.Any grating or grinding from calcium deposits along the hip joints can be evaluatedbetter in a sleeping dog than in one that is awake. Let sleeping dogs lie, indeed.If the pelvis is tipped only slightly to one side or the other, one hip thatisn’t normal can appear to be and one that is not dysplastic can appear to be.To complicate things, 10% of dysplastic dogs will be affected in only one hip.The X-ray should be done right.
X-rays can be done as early as at five or six months of age, if dysplasiais suspected. The advantage of radiography in a younger animal is that if youplan to breed it, you can save the time and financial and emotional expense relatedto breeding if the X-rays show unquestionable hip dysplasia. Again, the advantageof the PennHIP procedure is obvious, since dogs over four months of age can beevaluated.
It is very sad indeed for any pet owner to see his or her special pal affectedby the discomfort and mobility problems associated with Canine Hip Dysplasia.Armed with knowledge and forethought, highly selective breeding is your bestdefense against CHD.
Effects of Hip Dysplasia on the Muscles
Research has shown that dogs with CHD have significantly decreased sizes oftotal pelvic musculature surrounding and acting on the hip joint. Whether thisis a contributing factor or a result of hip dysplasia remains to be proven. Onemuscle that can contribute to worsening of hip dysplasia is the Pectineus Muscle.(See Exercise section.)
Effects of Hip Dysplasia on Ligaments
Attaching to the head of the femur from the center of the hip socket is atough fibrous ligament called the Ligament of the Head of the Femur. If thisligament is stretched or torn, the hip joint will be less stable—and this isexactly what happens to dogs with dysplasia. In fact, some of the first changesto take place in young dogs developing hip dysplasia occur in this ligament,especially if the muscle mass of the pelvis is underdeveloped. The ligament swells,develops tiny tears, and then stretches. In advanced CHD, the ligament can totallybreak down and cause more harm than good.
Effects of Hip Dysplasia on Joints
The joint capsule surrounds the joint and produces synovial fluid to nourishand lubricate the joint cartilage. In addition, the joint capsule provides somesupport to the joint. In dysplastic joints, the capsule becomes irritated, stretched,and scarred. In advanced cases the capsule loses its elasticity and inhibitsa full range of motion in the joint. A lot of the pain associated with hip dysplasiaoriginates from inflamed nerve endings in the joint capsule, so any pathologyhere will have a noticeable effect on the dog.
The surfaces of the head of the femur and the acetabulum are covered withwhat is termed hyaline cartilage. In a dysplastic joint, the points of pressureand the amount of pressure applied to areas of cartilage surfaces are abnormal.The cartilage is not able to function as it should, so it changes or disintegratesas a response. The changes range from thickening in abnormal areas to thinningin others. Sometimes the pounding it takes erodes the cartilage down to the underlyingbone. The result is more pain and discomfort, more inflammation, more calciumdeposits from inadequate healing attempts, and eventual breakdown of the jointas a unit. Nutriceuticals, such as Chondroitin Sulfate and Glucosamine, may beeffective in aiding the repair and maintenance of this articular cartilage.
Since bone is alive, it responds to stress and grows in a manner that tendsto distribute weight loads evenly. As a result of posture changes brought onby discomfort, the dog's weight-bearing forces stress the bone in unnatural ways.The bone does what it is supposed to do in response and changes its shape.
Hip Dysplasia Prevention
There are many different theories on how to prevent the progression of hipdysplasia. Nutrition, exercise, and body weight may all contribute to the severityof degenerative joint disease after hip dysplasia has developed. New informationconcerning other factors that contribute to hip dysplasia may come forward inthe future, but for now, we have to stick to what we know for sure. (If ownersinsisted on only purchasing an animal that had parents and grandparents withcertified good or excellent hips, then the majority of the problems would beeliminated. This is, of course, cold comfort to those needing care for dogs theyalready own.) Following the newer recommendations for exercise and nutritionmay help, but will never come close to controlling or eliminating the diseaseif stricter requirements for certified hips are not instituted or demanded.