Hip dysplasia (canine)

The hip dysplasia or hip dysplasia ( HD) is a malformation of the hip joint. This affects all breeds of dogs, with larger breeds develop the disease very often. It was first diagnosed at the German Shepherd Dog and is therefore placed incorrectly mainly in connection with this race, despite the fact that other breeds are more affected. The frequency of occurrence ( prevalence) can amount to over 50 percent depending on the breed. Even in domestic cats this disease can occur, especially among Maine Coon cats.

The HD is ( is the heritability between 20 and 40 percent) to a large extent genetically determined, which is why many breed associations call the HD - freedom for breeding approval. Since improper diet and posture can contribute to the development and progression of the disease, is a multifactorial ( many factors dependent ) events. Clinically, HD is reflected in the increasing restriction of movement and pain arising as a result of pathological remodeling of the hip ( coxarthrosis ). In the advanced stage, only the removal of the hip joint with or without implantation of an artificial hip joint to bring about a significant improvement. If this is not possible, can often maintain an adequate quality of life through lasting pain for long.

Symptoms and diagnosis

The severity of clinical symptoms of HD varies depending upon the age and stage of the disease. For relatively young animals, aged six months to a year, it comes to pain, because the head of the femur in the acetabulum ( acetabulum ) is only insufficient support and are irritated by its abnormal mobility pain registering nerve fibers of the periosteum of the glenoid rim. Older animals form of pain rather due to progressive degenerative changes ( osteoarthritis ) of the hip joint.

An incipient HD manifests itself in increasing pain when walking, the dog does not want to walk far, is more often out screams while playing occasionally and shows an unstable gait. When Browsing the hind limb the pelvis toward the pre- led limb is moved sideways ( CBM -twist ). For movements of the joint one pops, clicks or grinding of the joint can be audible. Upon detection of the symptoms of immediate trip to the vet is advisable.

Palpation

Already over stress on individual joints also unclear lameness of the hind limb in the presence of a HD can often be quickly mapped to the hip joint. The assessment of severe hip dysplasia often makes special tests required to make a statement about the joint stability can. Most commonly, the Ortolani test is used: The thigh is supported by lying on the healthy side animal at right angles to the spine. A launched on the knee hand pushes now under heavy pressure the femur towards the spine. In case of strong instability of the joint, they will lead to dislocation or subluxation of the hip joint. If now the thigh led away from the body axis, the femoral head slides with a click ( Ortolani -click) in the pan back. This test should be performed only by a veterinarian as possible, possibly in anesthesia.

X-ray

A reliable way to detect the degree of severity of the disease, is the X-ray examination. The joints need to be stretched, which causes severe pain in the presence of HD. Therefore, it is performed under general anesthetic. Prerequisite for a meaningful diagnosis is the exact positioning of the animal in the supine position with straight, parallel mounted thighs and perpendicular to the beam path screwed kneecaps. Additional pictures to be taken beam path in " frog position " of the thigh or in the side ( latero -lateral ).

An important evaluation criterion is the Norberg angle. It is defined as the angle formed is removed between the line connecting the centers of both femoral heads and the front edge of the socket ( see illustration). As for HD free animal he should be more than 105 ° ( yellow lines ). Other evaluation criteria are the congruence of the femoral head and acetabulum, the width of the joint space, the pan contour, the contour of the femoral head and the presence of evidence of arthritic processes such as roll-shaped thickening of the femoral neck, bead-rings at the joint socket located under the cartilage condensations of the bone in the socket region and the addition of bone ( osteophytes ) at the base of the joint capsule ( Morgan line). The Morgan line is a sensitive early marker for instability of the hip joint.

The breeding evaluation of HD recording is the VDH only by approved by the breed breeding associations appraiser possible to the vet send a contribution of the X-ray images.

Severities

Usually, a distinction is made between five different degrees of severity. The data in percentages refer to a study of 3749 dogs in the years 1991-1994 in Switzerland and give the distribution of the dogs on the different levels of HD.

Sometimes the levels of AD are still divided into A1 and A2, B1 and B2, C1 and C2 and D1 and D2.

Differential diagnoses

A diagnosis of hip dysplasia must be differentiated from other disorders of the skeletal system. In addition to fractures and dislocations, these are mainly tumors of the bone, which occur relatively frequently in the region of the femur in large dogs. In short statured animals aseptic femoral head necrosis ( Legg - Calvé -Perthes disease) must be distinguished. Furthermore, occur in rapidly growing dogs often detachment of the articular cartilage on ( osteochondritis dissecans ), which are also painful. Furthermore, diseases of the knee joint (eg cruciate ligament), pelvic fractures and diseases of the spine ( herniated disc, especially in small breeds ) and instability at the lumbar-sacral transition of the spine ( cauda equina syndrome, common in German Shepherd Dog) excluded.

Treatment

You can not cure HD, but only delay the onset of clinical symptoms and the progression of the disease or reduce the pain. The more often the dog performs certain movements, the faster wear the hip. These movements are mainly those that are particularly compress the joints, such as climbing stairs, jumping on hard surfaces and the like. You can allow the dog with The early detection and proper management of the disease a normal life.

The following treatment options:

• Drug therapy with anti-inflammatory and analgesic medications ( anti-inflammatories )
• PIN Operation: transection or removal of the musculus pectineus and Elevation of the joint capsule edge to suppress the pain-conducting nerve fibers. This is a very effective pain therapy, the effect lasts for several years.
• Capsular shift: Here, the joint capsule is tightened surgically. The surgery is only useful in young animals, unless definite signs of wear yet occurred and prevents subluxation and thus the progression of the disease.
• Pelvic osteotomy: For this, all three pelvic bone ( ilium, ischium and pubis ) are severed, the pelvis tilted slightly to one side and the bone then joined again by osteosynthesis. The aim is that the femoral head is the acetabulum better. This operation is complex and advisable only in young dogs in which no visible changes to the shape of the femoral head are made in terms of a beginning of arthritis.
• The insertion of an artificial hip joint is a very expensive treatment. The operation generally leads to freedom from symptoms to old age. It is important to support the dog during the subsequent muscle building through a lot of movement. Run the bike and swimming are ideal. Good results are also achieved with the additional medication by muscle building.
• Femurkopfresektion: Here, the joint head of the femur (caput femoris ossis ) is removed, followed by a connective tissue connection between the pelvis and femur developed. Connected with intensive physiotherapy, this method offers a good chance to live a pain-free life. Frequently stays by this treatment method but a permanent malfunction back.
• Stem Cell Therapy: The stem cell therapy, it is possible to rebuild cartilage and bring about a reduction in pain.
• Inserting one or more pins into the gold muscles at acupuncture points. The gold pins remain in the muscles. This method of treatment is to be classified in the field of alternative medicine, its efficacy has not been established.
• Physiotherapy: for pain relief and to build muscle.
• An orthopedic dog bed: but for pain relief, an effect has not been established.

Prevention

An inhibition of progression can through proper diet and not too much sport - be achieved - especially by little stress and the avoidance of upsetting and over-stretching of the hip joint. A physical therapy can relieve through the strategic structure of the pelvic and thigh muscles, the hip joint. The addition of cartilage-building supplement feed is another possibility.

To avoid the inheritance of the malformation, a certificate of HD - freedom for breeding approval is required for most dog breeding associations. But the pairing of HD - free parents animals does not guarantee that the offspring are free of HD. Many breed associations apply in the selection of a breeding evaluation.

Literature and evidence

• Leo Brunnberg: diagnosis of lameness in the dog. Examination, diagnosis, therapy notes. Parey Verlag, Berlin 1999, ISBN 3- 8263-3275 -X