ABSTRACT: This article aims to bring the reader up to date on current guidelines, along with a straightforward description of positioning for the BVA/KC hip and elbow schemes. The reader is reminded that the BVA/KC scheme is open to both Kennel Club registered dogs and non-registered dogs. This is especially pertinent with the relatively recent crossing of different pedigree breeds resulting in Labradoodles' and Cockerpoos', for example.

Hip and elbow screening schemes are available to owners of all dogs – whether Kennel Club (KC) registered or not – and with dogs of at least one year of age. They are a means of assessing the hip and elbow joints for signs of dysplasia and/or associated osteoarthritis.

The information gleaned from carrying out the procedure is particularly helpful to owners of potential breeding stock prior to first mating. The intention is to encourage breeding only from dogs well below the Breed Mean Score (BMS) and the aim is to reduce the incidence of hip dysplasia and osteoarthritis in future generations.

BVA/KC hip and elbow radiographs

Since 1st January 2010, dogs must be permanently identified (ID) with either an ear tattoo or a microchip. The veterinary surgeon submitting the films must ensure that the ID on both the paperwork and the dog match. This information must be placed as a primary marker, along with the date and Kennel Club registration number (if the dog has one).

If the dog isn’t KC registered and needs to have hips and elbows scored, the only ID required is the date and ID chip number. A left and/or right marker must also be placed as a primary marker.

Digital images should be submitted as dry laser images or high quality prints as, at present, disks are not acceptable. The image submitted should not vary by more than 10 per cent and a scale should be radiographed on to the image at the time of exposure.

One ventrodorsal, extended view of the pelvis (a grid should be used) is submitted for the Hip Dysplasia (HD) scheme and two views of each elbow –   flexed and neutral (without grid) – are required for the Elbow Dysplasia (ED) scheme

Radiation safety protection

The dog should be prepared under general anaesthesia or deep sedation to enable only mechanical restraint for the positioning of the animal. All four sides of collimation should be visible on the radiographs.

Hips

Positioning

The patient is placed in dorsal recumbency with the head and body held in a straight line, by means of a cradle or sandbags over the axillae. The hind limbs are drawn caudally and the hocks inwardly rotated. A tie is placed just proximal to the stifles.

A tie is also looped around each hock and attached to a small sandbag which is allowed to hang over the edge of the table. A foam wedge is placed under the hocks and a sandbag set on top to aid extension of the hind limbs and to help prevent axial rotation.

Landmarks

Feel for the greater trochanter and ensure the patellae are central.

Centre

Align on the midline at the level of the cranial edge of the pubis. 

Collimate

Collimation should include the body of the pelvis and extend caudally to the stifles.

Tips

An inch-thick table mattress is very useful when positioning for any radiographs, but particularly handy when positioning a bony dog for hip X-rays. Long boot laces can be used for tying the stifles – they tie securely and can be washed and reused many times!

Elbows

Positioning

The patient is placed in lateral recumbency, with the forelimb under investigation drawn cranially and the contra lateral limb drawn caudally, abducted and secured with a sandbag or tie. For the neutral view the angle between the humerus and forearm should be 110° and for the flexed view the angle should be 45°. A foam wedge should be placed under the carpus to ensure the carpus and elbow are in the same plane and there is no rotation of the limb. For the flexion view, a sandbag on top of the foot/carpus helps to keep the elbow joint in position.

Landmarks

Feel for the humeral condyles and ensure they are superimposed.

Centre

Align over the joint space.

Collimate

Collimation should include only the distal third of the humerus and proximal third of the radius/ulna.

Tips

When radiographing both elbow views on one cassette, try and have the elbow joints at the same level, as this makes it easy on the eye when reviewing. Also cover the side of the cassette not being used, to reduce scatter on the second image.

The submitted films

The films are scrutinised by two out of a panel of 11 veterinary surgeons with qualifications and experience in either – or both – radiology and orthopaedics. Film reading takes place weekly, with the session lasting several hours, during which time approximately 270 films are examined.

Reasons for refusal

There is a series of possible reasons for refusal by the panel to assess images.

•   documentary errors – incorrect dating of both parts, absence of information, incorrect information

•   labelling errors

•   poor positioning – centring and tilt (HD); degree of flexion/extension and rotation (ED)

•   image quality errors – processing, exposure factors

•   not using a grid – (HD) using a grid (ED)

•   digital – poor print quality, size.

What is the panel looking for? 

Hips

There are nine anatomical features (Figure 1) producing a numerical score between 0 and 53 for each hip. The scores of each hip are then combined to give a total score ranging between 0 and 106.

Figure 1: Hip evaluationThe BMS is published (see BVA/KC website) for each noted breed and the intention is that dogs well below that
mean – and ideally below 10 – may be used as breeding stock. However, it is important for the veterinary surgeon to convey to the owner from which of the nine parameters the score has arisen.

Scores arising only from parameters 1 to 3 are more likely to be inheritable traits, whilst scores from parameters 4 to 9 reflect secondary change, which may be influenced by environmental factors – exercise, diet, weight, for instance. It is also worthwhile researching the scores of other relationships to see if there is consistency and/or good selection criteria throughout the family.

Elbows

Elbows are scored individually with a range of 0 to 3 for each elbow. The margins of the joints and the bone structure itself are evaluated (Figures 2 and 3).

Figures 2&3: Elbow evaluation. On the neutral view. IFigure 2], the panel is looking at the radial head, the medial coronoid process and the ulnar notch. On the flexed view, (Figure 3], its members are looking at the medial and lateral epicondyles and the anconeal process

The degree of extension/flexion is obviously important, as is the degree of rotation.

Primary lesions and/or osteoarthritis will be given a score of 3, whilst the joint margins are measured and scored thus: <2mm = 1; 2-5mm = 2; >5mm = 3. The elbow with the highest score is the grade given for the dog. A low grade reflects little/no dysplasia.

Penn Hip scheme

The Penn Hip scheme is one of the hip screening schemes available in the USA. Three pelvic views are required – one VD extended view, one compression view and one distraction view. The latter two require the hips to be in a neutral stance’ position.

Until recently the stance' views were unachievable without ‘hand-holding’ and, therefore, contravened the Guidance Notes for Safe Use of Ionising Radiation within the UK. Recently, however, a technique has been developed to achieve these views without hand-holding and the scheme can now be carried out in the UK following training and accreditation by the Penn Hip organisation.

Training requires the veterinary surgeon to attend a compulsory one-day Penn Hip training course, followed by the accreditation process. Accreditation requires that you first purchase a ‘distractor’ device, and then you must demonstrate technique consistency by carrying out the three required views on five patients, along with two repeat stance views (a total of five films per dog). 

Training and accreditation is available to veterinary nurses under the supervision of a trained and accredited veterinary surgeon. Again, consistency of technique is verified, with films submitted as for the veterinary surgeon, along with one extra film per dog – positioned and taken by the supervising vet (a total of six films per dog).

It is the degree of laxity within the hip joint that is measured and this is termed the Distraction Index (DI). The DI ranges from zero (very tight) to one (very loose). The closer to zero, the more congruent the hip joint and, therefore, the smaller the chance of developing osteoarthritis.

The scheme has demonstrated that the degree of hip laxity can be reliably prognostic from the age of 16 weeks.

Conclusion

The aim of both the BVA/KC scheme and the Penn Hip scheme is to produce data and information for owners and breeders to enable them to make informed choices when breeding their dogs. However, in order to do this, the data available should be representative of the whole population of dogs within each breed.

Unfortunately many owners/breeders choose not to submit films from dogs that show obvious signs of disease. This produces a shift in the BMS produced by the BVA/KC. Once Penn Hip certified, the veterinary surgeon signs a clause to ensure that every dog radiographed for the scheme will have the films submitted –   regardless of the state of its hips. Perhaps this should be the case for the BVA/KC scheme?

Author

J L Riches-Tomei DipAVN (Medical) RVN

Julie joined Davies Veterinary Specialists in 1998, as part of a small team of VNs. Following completion of a DipAVN in Medical Nursing she was promoted to Nurse Supervisor (Diagnostics) with responsibility for what had become a large team of nurses. Returning to work in 2006, after the birth of her daughter, she was appointed Radiography Nurse and now enjoys spending time radiographing and CT scanning referred cases, all day. everyday!

To cite this article use either

DOI: 10.1111/j.2045-0648.2010.00012.x or Veterinary Nursing Journal Vol 26 pp 49-51

Veterinary Nursing Journal • Vol 26 • February 2011 •