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Canine hip dysplasia

How would you feel if you can determine whether your canine would suffer from canine dysplasia or not? Yes, hip scoring techniques just do that. But, if your canine is already suffering from this painful disease, there are ways to control them. Let’s see how.

The basics

Assessment of the coxo femoral joint (hip joint) for its congruity, conformity and the contoural landmarks of

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Dr. TN Ganesh

the femoral head and acetabulum through a radiographic view of the hip is called ‘Hip Scoring’. Based on the phenotypic expression of the polygenetic genes responsible for manifesting Canine Hip Dysplasia (CHD), further aggravated by the environmental factors such as diet, exercise intolerance, stress on the hip joints etc, the disease progress to damage of bone ends i.e. degenerative joint disease (DJD). Radiography is the confirmative tool to diagnose CHD. Scores are assigned to different criteria of the joint and are later summed up to reveal the hip scores. These scores in turn are helpful in arriving at a threshold score, in order to classify hip dysplastic dogs and differentiate from good hip joints.

The hip scores can be subjective or objective in nature. From the year 1930, all around the world, many methods of hip scoring procedures are practiced, of which, some renowned scoring schemes are Orthopaedic Foundation for Animals (OFA) method in the USA, BVC/Kennel Club method practiced in common wealth countries, Federation Cynologique Inernationale (FCI), Penn Hip (Pennsylvania Hip Improvement Program) method, etc.

OFA method

The most commonly used radiographic grading system for CHD, was established by the OFA. One function of the OFA is to provide a service for the diagnosis and registry of hip status for all canine breeds.

Here, under sedation, the patient in dorsal recumbency (lying in back) in standard hip extended view radiograph is taken and the coxofemoral joints are evaluated for the following factors:

  • Congruity of the femoral head (ball) and the acetabular (cup) margin.
  • Amount of coverage of the femoral head by the acetabular rim, as defined by the intersection of the femoral head physeal scar with the dorsal acetabular rim (at least 50 percent of the femoral head should be covered by the acetabulam). Remodeling (bone changes) and flattering of the femoral head.

Based on the criteria mentioned below, the coxofemoral joints are given one of the seven grades. In German Shepherds, evaluation of CHD by the OFA radiographic method has reliability for correct diagnosis of 69.9 percent at 12 moths, and 95.4 percent at 24 months.

Penn HIP method (Quantitative Radiography)

Radiograph showing severe hip dysplasia

The Pennsylvania Hip Improvement Program (Penn HIP) method is a stress radiographic method intended to provide a quantitative means of determining laxity (looseness) before the dog is 24 months of age. By correlating joint laxity with subsequent incidence and severity of CHD, this method can provide optimum predictive value.

The stress – radiographic method requires deep sedation or general anesthesia. The patients are positioned in dorsal recumbency, with the coxofemoral joints in a neutral flexion – extension angle to allow maximum lateral displacement of the femoral head. The neutral positioning avoids spiral tensioning of the fibrous elements of the joint capsule and hydrostatic influences that decrease hip laxity.

Radiograph – OFA Hip extended view

A compression view and a distraction view are obtained via the Penn HIP compression – distraction device. The distance between the centre of the acetabulum and the centre of the femoral head is measured on both views via templates or gauges. The distance is divided by the radius of the femoral head, a numerical value between 0 and 1 is determined (the distraction index). The index quantitates the relative displacement of the femoral head from the acetabular center.

In addition, the compression view delineates the articular surfaces and provides information concerning acetabular depth, thickness of articular carticular, and the center of rotation of the joint.

The distraction index quantitates passive joint laxity. Dogs with an index less than 0.3 rarely develop radiographic evidence of DJD. Hips with a distraction index of greater than 0.3 are considered to be susceptible to DJD.

Thus, the Penn HIP method shows promise for detecting susceptibility of CHD in dogs as early as 16 weeks of age.

Penn HIP Distraction radiographPenn HIP Compression radiographRadiograph showing FHNERadiograph showing THR

Treatment of canine hip dysplasia

The aims of treatment of CHD are alleviating pain, arresting secondary degenerative changes, and producing maximum joint function.

The treatment schedule for canine hip dysplasia should be based on:

  • age and health
  • clinical severity of the disease
  • radiographic appearance of the joint
  • intended function of the dog, and
  • financial constraints of the owner.

Medical therapy and management

The aim of medical therapy is oriented towards reducing pain and slowing the deterioration of the coxofemoral joint. Medical therapy should be reserved for patients with mild or intermittent clinical signs. Monetary considerations may prompt the client to choose medical therapy alone.

Exercise – the activity should be restricted to a level that the dogs can tolerate without signs of pain or exercise intolerance.

  • Short leash walks initially followed by gradual increase to maximum level of function does not cause pain or lameness.
  • Non-weight bearing activities (e.g. swimming) are excellent means of exercise and it avoids concussive trauma to the joints.
  • Severe exercise restriction results in increased exercise intolerance, loss of muscle mass and tone, decreased range of motion and exacerbation of cartilage (soft bone) destruction.

Weight – the patient weight must be maintained in the optimum range for the age and breed.

  • Obese patients should loose weight.
  • Diet control is a must by adapting to low caloric diet or maintenance – type dog food. Conservative therapy, consisting of exercise restriction and weight control, is effective in controlling pain and lameness in a significant number of dogs with CHD.

Anti–inflammatory and analgesic agents – anti-inflammatory and analgesic therapy using appropriate drugs is an adjunct in medically managed patients.

Surgical management

A hip dysplastic case which has progressed to osteoarthritis (damaged bones of joint) warrants a surgical management for effective pain reduction. The various surgical techniques adopted for the management of CHD are briefed as follows:

Pectineal myectomy: Pectineal myectomy (cutting the muscle) is proposed to relieve muscle spasm and the associated pain.

  • The pain relief has been attributed to release of muscle tension, reduced stress on the joint capsule and increased abduction resulting in articular alterations.
  • This procedure is performed bilaterally.

Triple Pelvic Osteotomy (TPO): Triple Pelvic Osteotomy (cutting bone in three places & joining after correction) is a surgical procedure designed to correct the biomechanical imbalances in a dysplastic hip, early in progression of CHD.

  • Hence, correction takes place before skeletal maturity and also before secondary degenerative changes to occur.
  • The goals of TPO are correction of femoral head subluxation and restoration of the coxofemoral weight – bearing surface area.

Femoral Head and Neck Excision Arthroplasty (FHNE): Femoral Head and Neck Excision Arthroplasty (cutting ball portion of bone) is a salvage procedure.

  • Joint function and pain are eliminated by FHNE and only a fibrous pseudo joint (false joint) exists. The pseudo joint is less stable than normal, and the range of motion is reduced.

Total Hip Replacement (THR): Total Hip Replacement (artificial joints) is a salvage procedure that can produce a functionally normal joint, eliminate secondary degenerative changes, and alleviate joint pain.

  • The candidate should be skeletally mature and have pain and/or lameness attributable to coxofemoral disease.
  • Here the affected joint is replaced with artificial (prosthesis) joint.

On a concluding note

The limited success in reducing the prevalence of CHD even in countries where hip scoring is routinely done and registries are made is due to insensitivity of detection methods, lack of parents or progeny considerations, and owner or breeder willingness to breed dogs with less than phenotypically excellent hips. Hence, routine hip scoring and breeding only those dogs achieving an excellent OFA rating at two years of age or dogs that have a Penn Hip DI of less than 0.3 at four months of age is indicated to control Canine Hip Dysplasia.

(The author is professor of surgery, Madras Veterinary College, Chennai and senior lecturer in Veterinary Surgery, Faculty of Medical Sciences, The University of The West Indies, Trinidad).

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Understanding canine Hip Dysplasia

It’s very disheartening to see our loving pal suffer from canine hip dysplasia, which causes discomfort and mobility problems. Here are a few ways to improve or eliminate its symptoms.

Canine hip dysplasia (CHD) is the most common development disorder of the hip joint, characterized by abnormal development of the hip joint. It usually occurs in both hind limbs, affecting both hip joints. Its effect ranges from very mild lameness to a crippling disease. Lameness may appear at any age.

Hip dysplasia is a hereditary condition and breeding of affected animals should be discouraged. The best way is to breed dogs with disease free joints based on radiographic evaluation and who have come from families with disease free joints. Do not breed dogs whose offspring have hip dysplasia. Dogs with hip dysplasia can produce normal pups and normal looking dogs can produce hip dysplastic pups.

How it occurs?Dog health

The hip joint is a ball and socket joint. The ball (the top portion of the thigh bone or femur) fits into a socket formed by the bones of the hip called the pelvis. In hip dysplasia, there is a loose and improper fit between the socket and the femur, the ligaments which hold them together also become loose, hence causing the ball to slide out of the socket partially in the initial stages (subluxation) and completely in long standing cases. When this occurs repeatedly, the ball gets worn out unevenly, causing erosions on its surface and exposing the underlying bone. Subsequently, bony proliferations occur (osteophytes) eventually resulting in degeneration of the hip joint (Osteoarthritis) and the dog becomes painful, lame and weak in the affected limb.

It is caused by multifactorial-genetics (polygenic-caused by many different genes), environment and nutrition (increased calcium and/or high calorie intake). However, the development of the disease is influenced by body weight, size and rapid growth patterns.

What are the clinical signs?

There are two types of clinical signs :

  • Young dogs who are between 5-8 months exhibit sudden decrease in activity, sore hindquarters, difficulty in rising and reluctant to walk or climb stairs. Initially, it may be noticed once in a while but will begin to get worse over time.
  • Older dogs show intermittent or continuous hind limb lameness after exertion, prefer to sit than stand, stiffness or difficulty in rising, reluctance to run and jump, short choppy steps of the hind limbs, loose or waddling gait, bunny-hopping when running and painful hip joint with decreased range of motion of hip. Shoulder muscles are stronger and thigh muscles are weak. Lameness and pain is usually due to secondary degenerative joint disease (DJD) and osteoarthritis.

How can it be diagnosed?

  • Physical examination : Laxity (excessive looseness of the hip), pain and/or crepitus (caused by rubbing of bony ends) of the hip joints.
  • Radiography : X-rays are taken to see the fit of the femur and pelvis and to look for bony changes in the hip joint. This is done under sedation. The severity of clinical signs often does not correlate with the severity of radiographic signs. Special radiographic procedures are also available to hip joints. Radiographic changes are seen between 6-18 months after which the disease progression is slow. They are graded by the principles laid down by the Orthopaedic Foundation for Animals (OFA) as borderline, mild, moderate and severe based on the radiographic evidence of damage to the hip joints. Another method of evaluation is a Penn Hip distraction method. Please consult your vet for further details of these procedures.

Radiographs are done to screen for presence or absence of hip dysplasia to select dogs who are suitable for breeding.

How can it be treated?

There is no cure but your dog’s pain and lameness can be managed by following certain conservative management procedures :

  • Restricting activity by limiting exercise to several regular 10 minute walks a day on a leash only for 6 weeks. Confinement to a small cage which encouraged the young pup to sit with his hind limbs spread was shown to reduce the incidence of CHD in genetically susceptible pups. 
  • Physiotherapy: Passive flexion and extension of hind limbs over a range of motion and distal to proximal massage helps prevent joint stiffness and reduces wasting of hind quarter muscles. 
  • Weight loss is absolutely essential for overweight and obese dogs. (To determine ideal body weight for each breed, consult your vet.) 
  • A restricted feeding programme during the rapid growth phase in suspected dogs. 
  • Pain control with analgesics: Consult your vet for the appropriate drug and dosage regimen. Do not selfmedicate. 
  • Chondroprotectives like glucosamine and chondroitin can be used. 
  • Acupuncture/shortwave diathermy/therapeutic ultrasound may give temporary relief from pain. 
  • Swimming is also useful – the aim being to build up muscle mass to support the hips. 
  • Surgical therapy: Surgery may be necessary if signs are severe and unresponsive to medical therapy or chronic in nature. 
  • In young patients, Pectineal myectomy (cutting the pectineus muscle) is an alternative to allow temporary pain relief. 
  • Triple pelvic osteotomy (cutting the bones of pelvis, rotating and fixing with special bone plates) are best performed before hip joint changes occur and is performed before the dog reaches skeletal maturity (usually within one year). 
  • Total hip replacements are indicated in skeletally mature animals with severe painful disease. 
  • Femoral head and neck arthroplasty: Surgical removal of femoral head and neck results in a false joint and pain free movement of hip. Best suited for dogs less than 25 kg. It is a common procedure that can be done with minimal instrumentation and gives good results.

(Dr. S. Ayyappan, M.V.Sc; Ph.D, F.ASIF (Swiss) has a Certificate in Canine Orthopedics (Swiss) and a Post Doc in Veterinary Surgery (USA). He can be contacted at: 9841249129/26475988, e-mail:jujups61@hotmail.com)

-Dr. S. Ayyappan

 


Did you know?

  • Canine hip dysplasia was first reported in 1935.
  • It is mostly seen in giant/large breed dogs like German Shepherds, Retrievers, St. Bernards, Labradors, etc.
  • Hip dysplasia can never be cured but clinical signs may be improved or eliminated with medical or surgical therapy.
  • The clinical signs may go through periods of exacerbation or remission throughout the animal’s life.