Overview of Hip Dysplasia

What is Canine Hip Dysplasia (CHD)?

Canine hip dysplasia is a genetic disease of dogs that causes looseness, abnormal development and arthritis of the hip joint. The hip joint is a 'ball-and-socket' type joint. The 'ball' is the uppermost part of the thighbone, or femur, and is called the 'head of the femur. The 'head' is connected to the rest of the bone by the 'neck'. The 'socket' is part of the pelvic bone, and is called the 'acetabulum'. Normally, the ball, or head of the femur, fits very tightly within its socket, or acetabulum. With hip dysplasia, this fit becomes loose and the joint partially dislocates, or subluxates. This subluxation can cause discomfort, abnormal development and arthritis, later in life. Hip dysplasia is usually a bilateral disease, which means both hips are often affected.

Canine hip dysplasia is an extremely common disease today, despite over 25 years of organized effort to reduce its incidence. Nearly one third of all orthopedic cases, seen at referral institutions, have hip joint disease related to CHD. According to the Orthopedic Foundation for Animals, the percentage of pure-bred dogs with CHD ranges from 1.8% to 48.1%, depending on the breed. Most commonly, CHD affects the large and giant breeds, although any breed can be affected.

Evolution of CHD

Hip dysplasia is NOT a congenital disease in dogs. This means that puppies are NOT born with loose hips, unlike human infants who usually have the problem at birth. In puppies, the looseness, or laxity, develops at around 4 months of age. Laxity alone can cause soreness in some dogs, usually in puppies 6 - 10 months old. Since the head of the femur is not seated well in its socket, the surrounding tissues are asked to provide more support than they are capable of, especially during exercise. These tissues can stretch and tear causing discomfort. Between the ages of 6 months - 2 years old, arthritis begins and progresses for the life of the pet. Severe arthritis also causes soreness, which usually occurs in the older dog who may have had problems as a puppy or who never showed any previous signs at all. Arthritis is the body's response to inflammation and hip laxity. The most notable changes that occur are the progressive thickening of the tissues around the joint and the production of bone around the head of the femur and acetabulum.

Causes of CHD

The specific mechanisms which cause CHD are not known. Genetics certainly plays a role, however, the specifics of how the disease is passed from one generation to the next, is very-complex and not completely understood. For example, puppies born from a breeding pair with hip dysplasia, although more likely to have the disease, may be completely normal. Similarly, normal breeding pairs, although more likely to have normal puppies, may produce offspring with severe hip dysplasia. This complexity with regard to genetics has frustrated efforts to eliminate the disease completely, and has led people to believe that environmental factors are responsible for disease expression, as well.

Nutrition and growth rate are considered to be important environmental factors related to CHD. There is strong evidence, from a number of studies, that dogs who are overfed, and gain weight too rapidly, are predisposed to CHD. This seems to be most important for large or giant breeds in the first 6 months of life. There is good evidence that puppies who grow more slowly have less chance of acquiring CHD. The final adult body size of these puppies is about the same as puppies who grow more quickly. Therefore, feeding premium puppy-foods, 'free-choice' to puppies, is NOT recommended, especially with large breed dogs, Additionally, providing vitamin or calcium supplements, is NOT recommended for puppies who are fed a balanced nutritionally complete dog food. Most reputable dog foods, even those for adult dogs, have all the vitamins and minerals puppies need. Veterinarians, or veterinary nutritionists, should be consulted when deciding how much of what food is safe to feed the growing puppy. 

Signs and Symptoms of CHD

Dogs showing signs of soreness with CHD can be any age and any size. However, most of the dogs are large, weighing from 45 - 90 pounds. Whether young or old, the signs of CHD are similar. Most commonly, an owner will notice that their pet is reluctant to exercise, work or play.

Common complaints are:

  • Limping or short-strided steps in the rear legs

  • Slow to get the rear-end up off the floor, and slow to lie down.

  • Difficulty with climbing stairs or jumping.

  • Tends to 'warm out' of the lameness (limping), which is worst when the pet first gets up, morning stiffness.

  • Tends to be worse after heavy exercise, usually the next day.

  • Some days are better than others, often cold and wet days are worse.

These signs of CHD rarely crop up, or worsen suddenly. Usually owners have perceived a problem for a long time and have noticed the signs getting worse slowly, over months or years. Additionally, the signs of CHD are rarely severe. Dogs usually show only mild to moderate lameness or soreness.

Signs of problems NOT consistent with CHD include:

  • All of a sudden, there's a problem with, the back legs, and there's never been a problem before.

  • There's been a mild problem for a long time, but die signs are suddenly much worse.

  • He/she is holding the limb up, completely off the floor.

  • He/she is having tremendous trouble sitting up and walking, and sometimes can't get up at all.

If any of these signs are present, the problem is NOT likely to be CHD. The most common rear-end diseases, mistaken for CHD, are knee and back problems. Knee problems usually cause the animal to hold the limb up off the ground, which is rare with CHD. Back problems, like slipped discs, cause injury to the spinal cord or nerves. Dogs with neurologic disease of the back will often walk uncoordinated in the rear-end, with a 'drunkard-type' gait. Some dogs will tend to scrape their feet or toe nails when walking. Both incoordination and dragging the feet are NOT usually seen with CHD.

Many different diseases can cause rear leg problems. Just because a dog has some arthritis of the hips, does NOT mean that the problem is, related to CHD or even the hips themselves. Determining the cause of rear leg problems is often difficult and requires consultation with an experienced veterinarian or orthopedic specialist.

Diagnosis of CHD

The Young Dog (under 1 year of age)

Deciding which tests to use when evaluating a dog for CHD depend significantly on the patient's age. As mentioned, younger dogs with CHD, tend to have notable laxity without much arthritis. Therefore, with younger dogs, the primary goal toward diagnosing CHD is detecting hip joint laxity. Palpation, or careful manipulation of the hip, is an extremely important tool. There are certain manipulation tests that are very sensitive at identifying laxity of the hip joint, Often the patient needs to be sedated, or anesthetized, in order to permit careful and gentle manipulations. Radiographs (x-rays) can also be very helpful when trying to identify laxity in the hip joint.

The Older Dog (over 1 year of age)

As mentioned, older dogs with CHD, tend to have arthritis, and less notable laxity. In these older dogs, the primary goal toward diagnosing CHD is detecting evidence of hip joint arthritis. Radiographs are the best method and the routine view, with the legs pulled straight back, provides a sensitive indicator for even the earliest signs of arthritis.

The Orthopedic Foundation for Animals (OFA)

The Orthopedic Foundation for Animals, Inc. is a private, non-profit foundation that has maintained a hip dysplasia registry since 1966. The goal of the foundation was to reduce the incidence of CHD by identifying dogs with affected hips so that they could be removed from breeding programs. When a dog is two years of age, radiographs are taken of the hips (the routine view) and a consensus, of three evaluations from veterinary radiologists, is reported back to the owner. Dogs are categorized as normal, borderline or dysplastic. Normal dogs are issued a breed registry number and the results are made public to the appropriate breed club. The OFA provides a reliable standardized evaluation for detecting arthritis in older dogs.

When is Treatment Necessary?

Whether younger or older, the clinical consequences of CHD are extremely variable from dog to dog. For example, some young dogs with laxity never develop arthritis, and some old dogs with severe arthritis never show signs of soreness.

Most veterinary orthopedic surgeons agree that if signs of limping or soreness are very mild, or absent, then treatment probably isn't necessary. Some owners worry about their pet being sore, yet not showing any signs. It is true that some dogs are more stoic than others, like people. But most dogs that are significantly uncomfortable, even the toughest, will show one or more of the signs listed earlier. In general, a dog with CHD that performs well, and can run, jump and play normally, probably does NOT need treatment.

Some owners, may request a surgical treatment because they would rather do the surgery on their pet when it is young and healthy, than later when the pet is older. Most of the surgeries are safely and routinely done on older pets. The modern anesthetic drugs are extremely safe, and anesthetic complications occur very rarely. Additionally, most of the surgeries, especially for the older dogs, do not become more difficult to perform with time, and some actually get easier. Remember, if your dog is not showing signs, there's no need to put him/her through a surgery now, that he/she may never need in the future.

Conservative Treatment of CHD

Conservative therapy can be a good option for many dogs, especially the younger ones, who may do well for years once they get over their first bouts of soreness. Conservative therapy has three-major components:

  1. weight control,

  2. use of anti-inflammatory drugs, and

  3. exercise restriction.

Weight control is extremely important. Obesity causes excessively high forces to be transmitted through already abnormal hips. Soreness may be exacerbated, and arthritis accelerated, in dogs that are overweight. The appropriate weight and diet program for your dog can be obtained from your veterinarian or from a veterinary nutritionist.

Anti-inflammatory medication is an important part of conservative therapy especially when soreness flares up. Aspirin is the most commonly used drug, however there are other oral medications or injections that can be very effective. Consult your veterinarian, or veterinary orthopedic-specialist, for the appropriate doses, medications and prescriptions. DO NOT treat your dog yourself. Drugs such as aspirin, acetaminophen (Tylenol) and ibuprofen (Advil, Motrin) can be extremely toxic to dogs when given an incorrect dose. The metabolism and dosages of some drugs are much different in dogs as compared to people.

Exercise must be controlled for conservative therapy to be effective. "Full-out" running, jumping and roughhousing should be prohibited as much as possible. Extended walks or jogs, on a leash, can be beneficial. When soreness flares up, exercise should be extremely limited for a few days. Often cage or kennel rest works best. Some owners mistakenly believe that their pet knows his or her own limits, and will restrict themselves as needed. In general this is not true. It could be argued that many people don't recognize their own limits, and will 'over-do-it' exercising, even though they're likely to regret it the next day. Most dogs are like these people. If allowed, they will run, jump or play to their fullest ability, even though they are likely to reinjure themselves. Owners must take responsibility for limiting the exercise for their pets.

Surgical Treatment of CHD

The three most common surgical treatments of CHD have three differing objectives. One objective is to save the dog's own natural joint by eliminating the laxity and preventing the progression of arthritis. This objective is usually reserved for the younger dogs who still have a joint worth saving. A second objective is to remove the source of the soreness by removing part of the joint itself. The arthritic femoral head and neck are removed and a 'false-joint' made of scar tissue and muscle eventually provides, relatively, pain-free movement. The third and final objective is to remove and replace the arthritic femoral head and acetabulum with an artificial joint. With joint replacement, dogs maintain normal movement and mechanics of the hip joint, and are pain-free very soon after surgery.

Saving the Natural Joint - Triple Pelvic Osteotomy

Triple pelvic osteotomy (TPO) is a surgery designed to save the natural joint by reducing or eliminating the laxity, or looseness. If the laxity is eliminated then the arthritis, which would follow, can be prevented. With TPO, the pelvis is cut in three places ('triple osteotomy' means 'three cuts in bone'), so the acetabulum, or socket, can be rotated over the head of the femur to prevent it from slipping out of the socket or subluxating.

The TPO is not appropriate for all dogs and works best in dogs that have no arthritis present in their hips. Dogs are usually younger (5-10 months old) when this surgery is performed, before arthritis has begun. Usually both hips are operated in two separate surgeries, 4 - 8 weeks apart. Most surgeons reserve this surgery for dogs that are significantly sore, and showing many, or all, of the signs consistent with CHD described earlier. Exercise must be severely restricted, for 2 - 3 months, to allow the pelvic bones to heat after surgery.

The TPO surgery has a good success rate if it is performed on an appropriate candidate; many dogs are improved clinically and arthritis is effectively prevented in some dogs.

Removing the Natural Joint - Femoral Head and Neck Ostectomy

Femoral Head and Neck Ostectomy (FHO) is designed to eliminate the source of discomfort by removing part of the hip joint. The femur is cut so that the head and neck of the femur are removed ('ostectomy' means' bone is cut and removed'). Scar tissue forms between the femur and acetabulum, where the femoral head and neck used to be; this is called a 'false-joint' because motion, between, the bones, is maintained without the 'true' ball-and-socket joint. Eventually, this scar tissue provides enough support to permit use of the limb without causing significant discomfort.

The FHO surgery is usually performed on older dogs, which already have significant arthritis. Usually one hip is operated on at a time, although some surgeons prefer to do both hips at the same time. One major advantage of the FHO is that exercise restriction is only needed for a few days after the surgery. After 10 - 14 days, exercise is even encouraged to accelerate formation of scar tissue.

The FHO surgery has a variable success rate. It can take up to 3 months for the dog to start using the leg well. Additionally, almost one-third of owners report that their dogs continue to limp or have trouble jumping, and 50% of owners report muscle atrophy (thinning) in the leg that was operated. Many surgeons feel that large or giant breeds do more poorly than smaller breeds, with FHO.

Replacing the Natural Joint - Total Hip Replacement

Total hip replacement (THR) is designed to eliminate the source of discomfort by replacing the arthritic joint with an artificial joint or hip prosthesis. The THR surgery is a state-of-the art procedure, very similar to the operation in humans. The arthritic femoral head and neck is removed and replaced with a metal head and stem (head- cobalt chrome metal; stem- titanium metal). The arthritic socket is removed and replaced with a plastic cup (high molecular-weight plastic). The metal head and plastic cup fit together like the original ball-and-socket joint, providing support and pain-free, mechanically sound movement almost immediately after surgery.

The THR surgery is performed on dogs 9 months of age or older, which have arthritis. Only one hip is operated on at a time, because most dogs will only ever need one hip replaced. The smallest-sized implants are often too large for dogs under 30 pounds. Exercise restriction must be enforced for 2 months, following the surgery, to allow all the tissues to heal around the prosthesis.

Total hip replacements have been performed in canine patients since 1974, and have enjoyed excellent results. Over 95% of patients return to normal function after the surgery. Over 80% of dogs-do NOT need a second surgery despite the presence of arthritis in the other hip. Animals will run, jump and play as they did before the discomfort hindered them. Working animals, including police and hunting dogs, have successfully returned to their duties after THR.

Other Surgeries

Other surgeries have been reported as beneficial in the treatment of CHD. These surgeries, designed to reduce soreness and eliminate the laxity associated with CHD, include Intertrochanteric osteotomy (ITO) and pectineal myectomy. Although there may be occasional indications for these procedures, nether has been shown to reliably prevent the progression of arthritis. Therefore, any improvement noted post-operatively with these procedures, may be short-lived.

Where can you get more information?

Canine hip dysplasia is a common disease, however, many diseases can mimic it's signs and complicate diagnosis. Canine hip dysplasia is also a complex disease with numerous treatment alternatives. Deciding which treatment is best for your dog depends on numerous factors, including: severity of the signs, the dog's age, your pets purpose in life (i.e., pet, hunting or police) and financial concerns. The surgical procedures, if needed, are difficult to perform and often require the services of surgeons with advanced training. If you have questions about CHD, your first step should be to call or schedule an appointment with your local veterinarian. If additional help is needed, your veterinarian can schedule a consultation with the nearest veterinary orthopedic specialist.


Acetabulum- The socket component of the hip joint, and part of the pelvis.

Arthritis- a chronic degenerative condition of the joint which can cause pain and is usually associated with added bone around the joint.

Atrophy- a wasting, or loss of mass, especially muscle.

Bilateral- on both sides, left and right.

Congenital- present at birth.

Dysplasia- abnormal development of a body part.

Dysplastic- having canine hip dysplasia.

Femoral- relating to the Femur.

Femur- the thigh bone.

Lameness- abnormality in gait, limping.

Laxity- looseness, usually related to a joint.

Luxation- when a joint is completely out of place, or dislocated.

Ostectomy- a cutting and removing of bone.

Osteotomy- a cutting of bone, as with a saw.

Pelvic- relating to the pelvis.

Pelvis- the basin-like skeletal structure that connects the spinal column to the hind limbs.

Prosthesis- an artificial device used to replace a missing body part.

Radiographs- x-rays

Subluxation- when a joint is partially out of place, or partially dislocated.

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