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Hip Dysplasia and Hip Scoring

The Saint Bernard Club Inc

Understanding Hip Dysplasia and Hip Scoring
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Hip Dysplasia is by definition an ill fitting hip. This can be caused by having shallow sockets, abnormal heads and necks of the femur and from excessively loose ligaments. Hip Dysplasia is a polygenetic inherited condition that is affected by environmental influences such as weight, diet and exercise, which can interact to cause rapid wear and tear of the hip joint leading to arthritic change.

Hip Dysplasia is a definite problem in Saint Bernards that needs to be assessed and taken into account before heavily working or breeding with an animal.

Hip Dysplasia is a complex genetic and environmental problem but should be kept in its proper perspective relative to the breed as a whole. It is one genetic problem, not the only one.

The Australian Veterinary Association (AVA) has a scoring scheme that is Australia wide with averages produced for each breed. The average for Saint Bernards in 1991 was 21.2, the Club has suggested a combined mating total for both dog and bitch of 45 with neither dog or bitch being in excess of 30 as a guideline.

Ideally one should breed from stock that is at or below the breed average. See Standing Order 1.18 & 1.19.

X-rays are taken by your vet and are sent into AVA for grading, you receive back a certificate with their assessment.

Scoring is done on 9 different points of the hip joint anatomy and each area (apart from the caudal acetabular edge which is out of 5) is scored out of a possible 6 points. The lower the score, the better the hips. The maximum score per hip is 53, with an overall total of 106. The score is usually expressed as e.g. 0/3, where the first figure is the total score achieved in the right hip. A score of 51/48 would indicate that both hips are severely arthritic.

The first two areas scored, the Norberg angle and subluxation, are considered to be more influenced by environmental factors e.g. excessive weight, which can give a greater degree of looseness of ligament. The other areas scored all involve arthritic changes and are considered to have a high degree of inheritance.

POINTS OF THE HIP JOINT ANATOMY

1. Centre of the femoral head
2. Cranial Acetabular Edge
3. Dorsal Acetabular Edge
4. Cranial Effective Acetabular Edge
5. Acetabular Fossa
6. Caudal Acetabular Edge
7. Femoral Head/neck Reconturing
8. Femoral ahead Reconturing.
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Hip Scoring - A Standardised System

Introduction

The first significant reports of hip dysplasia appeared in the 1930's and since this time much has been written about the disease.

Hip dysplasia simply means an abnormal development of the hip joints resulting in degenerative changes.

The disease is genetically inheritable and is passed from sire or dam to offspring but as the gene has incomplete penetrance, an animal may carry the gene for hip dysplasia without displaying any signs themselves. This means that parents with normal hips can produce offspring with severe hip dysplasia.

An added problem is the poor correlation between radiographs (x rays), the major diagnostic tool, and the clinical signs, therefore a dog may appear to be sound in the hips but have severe changes on radiographs.

Obviously this is a complex disease and in an attempt to identify affected dogs and classify the severity of the dysplasia, a number scoring systems have been developed. These schemes are difficult to relate to each other, so a standardised system is necessary to gain the maximum long term benefit to breeds as a whole.

From 1st July 1989, the Australian Veterinary Association (AVA) introduced a scoring system developed by the German Shepherd Dog League in the UK and now the standard method of assessment of the British Veterinary Association (BVA).

Procedure for Scoring

All veterinarians in Australia have access to the scheme and only a single radiograph is required. Application forms can be obtained by your veterinarian from the AVA office and a two generation pedigree must be included on this form.

Preferably the dogs ID/tattoo number or otherwise registration number should be recorded on the radiograph.

It is essential that your dog be given a general anaesthetic for the radiographs as the dog must be correctly positioned on its back with hind legs extended and parallel to each other. The entire pelvis and hind legs to the stifles must be included and the legs held as close to the x-ray plate as possible. Obviously even the quietest dog would be difficult to restrain in this position without an anaesthetic.

Any tilting of the pelvis is undesirable as it usually improves the appearance of one hip and makes the other look worse than it actually is, making accurate assessment difficult.

The radiograph and completed form are submitted to the AVA National Office with a fee and stamped addressed envelope should be included so that the results maybe forwarded to the issuing veterinarian. All radiographs are retained for research purposes.

Scoring is done to the BVA/GSDL scoring system and the scoring sheet will be sent to your veterinarian who will interpret the results for you.

The pedigree information gathered is summated to give an overview of the situation in the major breeds and reports will be presented annually to veterinarians.

A detailed account of the method of scoring is most necessary for this discussion, however a brief description of the major points taken into account may help the breeder understand the significance of the figure which has been arrived at.

Each hip joint is assessed separately using nine features shown in the below diagram. Each feature is assessed according to written guidelines and given a number from 0 to 6 being grossly abnormal and 0 normal. The addition of these figures for both hips results in a score between 0 and 106. Therefore, from this it can be seen that the higher the score, the more abnormal the hips are.

The nine features looked at are designed to indicate the degree of subluxation of the joint (ie. how unstable the joint is) and the severity of the degenerative changes to all parts of the joint. See bottom diagram.

When the overall score is arrived at, more weight is given to the degenerative changes as these are considered to be more significant in the disease.

So Your Dog Has a Hipscore - What Now?

By comparing your dog's score with data collected for the particular breed Australia wide, an assessment can be made as to whether your animal is suitable for breeding. Because the dog is assessed with others of the same breed, there is less pressure from other breeds which naturally have "better" hip conformation. Thus a Rottweiler's hips, for example, are not expected to be the same as those of a Greyhound. Your veterinarian will assist you with this.

The advantage of this scheme is that it allows comparison within the breed and selection of the best hips of that particular breed. Also, due to the previously described genetic nature of the disease, sires and dams with normal hips but which consistently produce offspring with poor hips may be "weeded out".

With the increased awareness of breeders to the problem of hip dysplasia and this standardised scoring system, the future will hopefully see a gradual improvement in hip conformation.

EXTRACTED FROM A PAPER BY DR SANDRA LISTER, BVSC (HONS), MACVSC
PRINTED IN THE PAL DIGEST SPRING 1989

(เฉพาะผู้มีส่วนเกี่ยวข้องและลูกค้า The Spirit of Saintbernard)

Create Date : 15 กรกฎาคม 2551

Last Update : 1 สิงหาคม 2551 4:01:31 น.

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