What Is Hip Dysplasia? |
KC/BVA Hip Scoring Scheme |
Cocker Spaniel Health Testing |
The current BMS for cocker spaniels is 13 (total of both hips) - [2009/2010]
The procedure for hip scoring is as follows:
The dog is taken to the owners own veterinary surgeon. The owner of the dog competes the "green" form confirming the identity of the dog and giving permission for the results (the score) to be published by the Kennel Club. The microchip of the dog is read and that number together with the dogs sire and dam's details are also entered onto the "green" form.
The next step it to anesthetise (general anaesthetic or heavy sedative) the dog (so he can be manipulated into the correct position without struggling or moving). Once under anaesthetic/sedation the dog is placed into position for X-Ray. The traditional positioning of the dog for hip scoring is for the dog to be placed on his back (the dog should lie true i.e. not twisted) with supports to prevent him from rolling to one side.
The dogs kennel club registration number and the microchip no. are placed next to the dog and the letter "R" to indicate the right hand side is placed under the dog (adjacent to the hips), these are made of metallic materials so they show up on the X-Ray film.
Positioning
The vet will manipulate the pelvis & hips of the dog so that they are rotated whilst at the same time ensuring that the legs (femur) to kneecap (patella) are straight and extended. To ensure the legs remain straight, the legs are taped together and the feet are raised on a pad.
Now that the pelvis is rotated, the dog’s legs straightened, the patella's (kneecaps) are aligned the pelvic area is radiographed. Once the film has been developed, the dog is brought round from the anaesthetic (or given a reversal agent if sedated) and the procedure is complete.
Poor Positioning & Better Positioning
In the X-Ray's above, despite poor positioning (the femur bones are not straight) the 'ball" & "socket" position is similar & wouldn't adversely affect the score for those areas, however the score for the 'Norberg Angle' would rise dramatically as the angle is decreased due to the rotation of the "ball" within the "socket".
Poor positioning has the potential to alter a score considerably (for the worse!). The film is for the same dog, the first film was rejected and a second taken!
When the procedure is complete, the "green" form together with the x-ray picture (film) and the fee to the BVA is posted to the BVA by the veterinary surgeon. When the dog's hips have been scored, the "green" form (now complete with score and the scorers signature) is posted with the x-ray films back to the submitting vet. The "green" form is then issued to the dog’s owner.
Please visit this link (to the BVA) for full details about the procedure.
When to hip score:
The minimum age for hip-scoring is 12 months there is no maximum age. It should be noted that the older a dog is when it is scored may have a slight impact on the results (slightly higher score, but not significantly so) due to natural wear & tear and the aging process, scoring older dogs does however give a more accurate result. However, an older dog being scored will NOT show dysplasia on an X-ray film due to more advance age unless the dog already has dysplasia.
The costs involved:
The cost of hip-scoring comprises two parts a) the set fee payable to the BVA (for scoring) and b) the fee to your own vet for the anaesthetic, time taken to perform the procedure & for the cost of the radiographic film (the x- ray film).
Our dogs are immobilised via heavy sedation which takes 10 - 15 minutes to take effect ('Domitor'/'Torbugesic'), and not a general anaesthetic, when the procedure is complete they are given a reversal agent ('Antisedan') & rouse within about 5 - 10 minutes. Any dog having a general anaesthetic will need to remain at the veterinary surgery for several hours to ensure he has recovered from the anaesthetic.
The BVA fee is set annually (each January) & is currently £50.00 (inc. VAT) [2011]. The veterinary costs will vary from vet to vet and also to some extent on the weight of the dog (heavier dog = more sedation agents/anaesthetic!).
Our Costs:
- Vet's Fee: £115.00 approx. - based on the weight of the dog
- BVA Fee: £50.00
Total: £165.00
Below is a copy of one of our dogs "green" forms. Personal details are fictitious (the score has been unaltered).
Here is the x-ray film that relates to the above score. The hip joint is a "ball" and "socket" joint and is marked with a red arrow.
Each of the dogs hips are scored 0 - 6 points (0 is good 6 not so good). There are nine areas focused upon. All areas are important but the area thought to be the most important is the "Norberg Angle" & the "Subluxation".
The first 3 (out of 9) parts of the score relate to the conformation of the hip, scores in the remaining 6 indicate secondary changes i.e. arthritis/degenerative joint disease. Healthy dogs should have scores of "0" in the remaining six aspects of scoring.
Anatomy of the hip:
| Norberg angle | - | This is the angle formed by a line connecting the centres of both femoral heads and one drawn between the centre of a femoral head and the craniodorsal rim of the acetabulum on the same side. It is a means of assessing hip laxity and is used in the detection of hip dysplasia. |
| Subluxation | - | Means the partial displacement of a joint in this case the displacement of the head of the femur. |
| Cranial acetabular edge | - | The score indicates the degree of minor alterations in the shape, contour and possibly the length of the CrAE are generally believed to be indicators of poor articular congruence, while more severe changes are clearly consequences of chronic instability, abnormal marginal wear and remodelling of the joint. |
| Dorsal acetabular edge | - | Forms a well defined interface which traverses the Femoral Head almost vertically and extends a little beyond it cranially and caudally. |
| Cranial effective acetabular rim | - | The earliest detectable abnormalities of the CrEAR are either minor exostosis (outgrowth from a bone), usually in the form of a small, well-modelled osteophyte (small abnormal bony outgrowth), or slight 'rounding off' of the junction between the CrAE and DAE. |
| Acetabular Fossa | - | Detectable bone deposition in the AF is almost always associated with marked subluxation and the amount tends to increase in proportion with the increase in the other radiographic hallmarks of secondary degenerative joint disease (osteoarthritis). |
| Caudal Acetabulem Edge | - | The CaAE is the segment of the acetabulum which is subject to the widest range of normal radiographic variation. Radiographic abnormalities are scored between 0 and 6 and changes are due mainly to exostosis (outgrowth from a bone) with signs of wear being apparent only in advanced cases. |
| Femoral Head and Neck Exostosis | - | The normal FH should have a smooth roundish profile, but the shape may vary considerably. |
| Femoral Head Recontouring | - | This criterion is used to record the extent to which the FH shape is altered as a consequence of instability. Thus scores are likely to be awarded only in cases in which secondary changes are well established, when remodelling occurs as a result of the combined effects of periarticular new bone formation and loss of subchondral bone following total destruction of articular cartilage. |
Key to the anatomy of the hip (the points scored):
- Cranial Acetabulem Edge
- Cranial Effective Acetabulem Rim
- Dorsal Acetabular Edge
- Caudal Acetabulem Edge
- Cranial Effective Acetabular Rim
- Acetabular Fossa
- Femoral Head
Norberg Angle
Under the KC/BVA Scheme, the Norberg Angle is one assessment criteria out of a total of nine areas. It is therefore technically possible for a dog to score less well on this aspect but still be determined to be none dysplastic due to better scores on the remaining 8 areas of assessment including the "Subluxation". However it is generally agreed that a poor Norberg Angle is linked to "Subluxation" and degenerative changes in the other areas of examination, therefore the "Norberg Angle" will usually have a significant contribution to whether secondary changes are evident & therefore scored higher.
By comparison, countries using the FCI Hip Scheme, the Norberg Angle is I believe the sole determinant of a dogs hip conformation. Ideally a UK BVA score should indicate '0" for each hip on the Norberg Angle. The Norberg Angle provides a quantitative assessment of the degree of congruence between the femoral head (FH) and acetabulum; the length of the cranial acetabular edge (CrAE), which gives a relative indication of acetabular depth and a measure of coxofemoral subluxation (laxity).
To calculate the Norberg angle:
Take the centre of each femoral head (hip ball) and draw a line between them. Then take the centre of the femoral head and draw a line to the outer point of the pelvis. The angle between these lines is the Norberg angle. The Norberg angle is calculated for each hip joint. The Norberg Angle ranges from 55 to 115 degrees.
Dogs with scores above 105 degrees are accepted as having normal hip-joint conformation, hips are 'good' with angles of 100-105 degrees, fair with angles of 100 degrees. Dogs with scores of 90-95 degrees indicate moderate dysplasia and finally dogs with angles of less than 90 degrees equal severe dysplasia.
Lower scores indicate that hip laxity is present as the 'ball' is not deeply contained within the 'socket' thereby creating less angulation (90 degrees is defined as an acute angle). Good Norberg Angles always depict the line pointing to the outside edge of the body, angles which are nearing perpendicular indicate poorer conformation & angles pointing towards the centre line of the body indicate very poor conformation the closer they deviate from 90 degrees to the centre of the body, in summary this means that the lower the degree of angle the poorer the conformation of the joint.
If the angle is correct (105 deg or above) the score given by the BVA will be '0'. The X-ray below scored '0' for the Norberg Angle on both the left and right hand sides.
Method Of Measuring the Norberg Angle (in degrees)
Norberg Angle Measurements (approx.) for this X-Ray
Norberg Angle Measurements (approx.) for this X-Ray
For more information about canine hip dysplasia please visit our hip dysplasia page.