CONTRIBUTOR(S): Vetstream Ltd, John Houlton,
Elbow dysplasia – BVA/KC scheme
Elbow dysplasia – BVA/KC scheme
Elbow dysplasia (ED) is an important cause of lameness in medium to large breed dogs. Dysplasia means abnormal development and ED is an inheritable, developmental condition that causes lameness in both young and older dogs.
Young dogs may be lame from multiple types of abnormal cartilage development or from joint incongruity (incorrect alignment of the joint surfaces). These dogs will develop osteoarthritis at an early age which becomes progressively more severe as they grow older. Other dogs may not show lameness as puppies but exhibit arthritic changes in later life. However, there are many dogs with subclinical disease that show no sign of lameness but still have an increased risk of producing affected offspring. These dogs can only be detected by screening.
Elbow dysplasia is a difficult disease to treat and osteoarthritis is a common sequel which may cause severe lameness in later life. Prevention is definitely better than cure!
What is the BVA / KC elbow scoring scheme?
The BVA/KC Scheme was introduced to identify affected dogs and to provide advice to breeders in order to reduce the prevalence of the condition. Elbow radiographs of any breed of dog (including non-registered animals and crossbreds) may submitted to the scheme. Nevertheless, the scheme is particularly recommended for those breeds where elbow dysplasia is common.
The current BVA list includes:
- Basset Hound
- Bernese Mountain Dog
- English Mastiff
- German Shepherd Dog
- Great Dane
- Irish Wolfhound
- Newfoundland
- Golden Retriever
- Labrador Retriever
- Rottweiler
Submission to the scheme is a two stage process. The first stage involves your veterinarian taking radiographs of your dog’s elbows. Any breed of dog is eligible but dogs must be at least one-year-old. There is no upper age limit. The dog’s KC registration certificate and any related transfer certificates must be available so that the appropriate details can be printed on the radiograph. Additionally your veterinarian will also check your dog’s microchip/tattoo numbers which will also be printed on the radiographs.
Dogs will need to be sedated or anesthetized so appropriate arrangements should be made with your veterinarian. Frequently, radiographs are taken for the hip and elbow dysplasia scheme at the same appointment. Payment for the radiographs is made to your veterinarian.
Owners should sign the declaration (first part) of the certificate, to verify the details of the dog are correct and grant permission for the use of the results.
The second stage involves submission of the radiographic images by your veterinarian to the BVA together with the scoring fee made (payable to the BVA) and the part-completed certificate of grading. The veterinary surgeon submitting the X-ray certifies that the X-ray was taken on the date indicated and the dog’s identity is correct.
How are the radiographs interpreted?
The radiographic images are examined by two panellists who assess them using an internationally recognized scoring scheme. Panellists are appointed annually by the BVA and each year they undertake a quality assurance exercise to ensure consistency of interpretation.
Points are awarded for changes seen in the elbows with each elbow being given a grade.
Four grades are possible for each elbow:
0 = unaffected.
1 = mild changes.
2 = moderate changes.
3 = severe changes.
The overall grade of the dog is that of the higher graded elbow. For instance, if the left elbow is graded as 2 and the right as 3, the overall grade of the dog is three.
The scrutineers complete the certificate and sign it. It is then returned to the submitting veterinarian together with the radiographs if they are not digital images.
Once a certificate has been issued further radiographs of the dog may not be submitted for regrading. Owners may appeal against the original grade but these must be lodged with the BVA, in writing, within 45 days of grading. The original radiographic images and an appeal certificate must be submitted by the owner’s veterinarian to the BVA. These will be reviewed by a second pair of panellists and re-graded by the Chief Scrutineer whose decision will be final.
Occasionally radiographic images submitted to the scheme are rejected because they cannot be scored accurately. This may be due to technical problems with the image or inaccurate positioning of the elbow. Scrutineers must be confident that the grade they give is correct and if there are features that are open to misinterpretation it is in the dog’s interest that better images are submitted. Incorrect identification of the patient will also result in return of the radiograph and certificate for the error to be corrected.
How are the grades interpreted?
Responsible breeders should select their breeding stock (both dogs and bitches) only from animals with an overall grade of 0. Infrequently, offspring may be affected even though both parents had zero scores. This is discouraging but it should be remembered that a random assortment of genes will occasionally result in a disappointing genotype. Such disappointment can be reduced by considering the dam and sire’s Estimated Breeding Values (EBVs) to determine the genetic risk for each dog passing the disease to their offspring. EBVs are a more accurate indicator of genetic risk than using an individual dog's elbow score alone. EBVs link all available pedigree information with data collected through the BVA/KC elbow dysplasia scheme. The information on relatives (who share genetics) influences the genetic risk of an individual. Therefore, the more dogs that are scored under the scheme, the more accurate the EBV will be. This is reflected in the confidence of the EBV which is an indication of how much scoring information has been used to calculate the EBV. The more scoring information available, from the dog itself and/or its relatives, the greater the confidence that the EBV is close to the actual genetic risk.
A dog's EBV can change during its lifetime, either upward or downward, as more information becomes available, either about the dog itself, or its relatives. Ideally breeders should use dogs that that have an EBV which is lower than average (ie a minus number), and preferably with a confidence rating of at least 60%. Dogs with an EBV which is higher than average can still be bred from with care, providing they are mated to a dog with an EBV which is well below average (assuming that the confidence for both dogs is high). If a dog with less than an ideal elbow score, but a low EBV that has a good confidence, is bred from, its offspring should be carefully monitored and preferably they should be elbow scored themselves.
EBVs are available on the Kennel Club website under MateSelect (https://www.thekennelclub.org.uk/services/public/mateselect/Default.aspx ). Due to limited available data, not all breeds have published EBVs.