Complex inherited disorders

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Complex inherited disorders are often caused by a number of different genes and are also influenced by environmental factors, such as diet and exercise.  The way in which these conditions are inherited is not straight forward; hence the name complex inherited disorders. 

Where tests for these conditions are available, dogs are often tested through grading systems, which rate to what degree the dog is affected by the condition. Complex diseases can cause clinical conditions that worry breeders the most, such as hip and elbow dysplasia, and heart disease. These complex diseases are usually seen across many different breeds and are also described in both cross breeds and mixed breeds.

Which tests are relevant to your breed?

Before breeding, check whether any of the conditions mentioned below may be relevant to your breed. Information on the tests that are available and recommended can be found on our Breed Information Centre, or by contacting your veterinary surgeon, breed club, and/or your dog's breeder.

The results of dogs tested under any of the BVA/KC health schemes are published on the Kennel Club's online health resource Mate Select and in the quarterly publication, The Breed Record Supplement.  Mate Select is free and easily searchable, assisting breeders wishing to check on the health status of a potential mate for their dog.

What tests are available for complex inherited disorders?

The Kennel Club, in conjunction with the British Veterinary Association (BVA), currently run four clinical screening schemes:

It has been designed to address the problem of hip dysplasia. The scheme evaluates radiographs that have been taken of an individual dog's hips. Each hip is evaluated by two experts who score nine anatomical features of the hip and score each hip out of a total of 53. The two hip scores are then added together to give an overall total hip score. So, a dog's hip score can range from 0 to 106, and the lower the hip scores the better the anatomy of the dog's hips.

In breeds where significant numbers of dogs have been through the hip scheme, it is possible to calculate a breed mean hip score, which gives a feel for the average score within that breed.

For additional information on considering hip score results when breeding you may also wish to read the section below on estimated breeding values.

It has been designed to address elbow dysplasia. Each dog is assessed from radiographs that are taken of the dog's elbows. Each elbow is graded on a scale of 0 to 3, by two specialists. The lower the grade, the better the anatomy of the elbow. In this scheme, if the dog has two different elbow grades, the higher of the two is used as the dog's elbow grade.

has two lists, Schedule A and Schedule B. Schedule A contains all of the known inherited eye diseases and the breeds that are currently known to be affected by these conditions. Schedule B, lists breeds and conditions where further investigation is urged. Specialist panellists, appointed by the BVA, can examine any individual dog for clinical signs of these diseases. Some of these inherited eye diseases are not present from birth and breeders especially are advised to have their breeding stock examined throughout their dog's life.

View the schedule A or schedule B lists here.

MRI scans, scanned under BVA procedures, are reviewed by a panel of BVA appointed neurologists and radiologists and graded by two scrutineers. Grading is assigned according to the severity of the CM and SM changes. As CM/SM is a progressive condition, scans throughout the dog's lifetime are recommended, generally at years 1, 3-5, and over 5.

Procedure Notes, submission details and breeding advice are available for all these schemes from the BVA Canine Health Schemes (CHS) office, for more information, visit www.bva.co.uk/Canine-Health-Schemes/

Breed Clubs health screening schemes

In addition to the BVA/KC Health Screening Schemes, many breed clubs support dog health and good breeding practices through their own health improvement strategies and health screening programmes. These programmes are organised by the breed club using specialist veterinarians that they have identified. The results of these screening programmes are collated and disseminated by the breed clubs.

To find contact details of your local breed club, please visit our Breed Information Centre.

BAER Test Health Programme

The BAER (Brainstem Auditory Evoked Response) test (PDF) is used to evaluate the hearing of a dog by detecting the electrical activity of the brain in response to an auditory stimulus (usually clicks), which is recorded and displayed on a computer screen. The test is a reliable method for determining whether a dog is deaf and for measuring the extent of its hearing loss. However, the test does not measure the full range of canine hearing, only hearing in the normal human range (some dogs will test as 'deaf' but can still hear very high pitched noises).  

Breeding advice for complex inherited disorders

Where health testing is recommended for your breed, it is important that any potential breeding stock is tested prior to mating. The results of these tests should be carefully considered and used responsibly to produce healthy puppies. If any of the BVA/KC health schemes are recommended in your breed, then once you know the results for both the potential sire and dam, you may wish to refer to the scheme specific advice found on the clickable links above or from www.bva.co.uk/Canine-Health-Schemes/.

It is important to ensure that you also take into consideration all health test results, the general health of each parent, the inbreeding coefficient of the potential puppies that could be produced, the temperament of the dogs and their conformation.

How complex inherited disorders are passed on to any progeny is not straight forward and so you may wish to also consider the results of any breeding dog's parents, grandparents, siblings and previous offspring.

Estimated Breeding Values

As mentioned above, complex disorders, such as hip and elbow dysplasia are inherited in a complex way and the extent to which an animal is affected is also influenced by their environment. Estimated Breeding Values, or EBVs, are a resource that can be used by breeders to assess the degree of risk to which an animal may have inherited, and pass on, genes associated with a particular health condition.

Currently EBVs are available, via the Kennel Club's Mate Select, for hip and elbow scores and are calculated using data from the BVA/KC hip and elbow dysplasia screening schemes. EBVs are a more accurate way of measuring a dog's genetic risk, than by using the scores from the BVA/KC schemes alone. EBVs take into consideration a dog's hip or elbow score, as well as the scores of all of their relatives. By using this additional data, it excludes non-genetic or environmental factors.

You can currently find EBVs for hip scores for 15 breeds and elbow scores for 5 breeds on the Kennel Club's Mate Select resource, available at www.mateselect.org.uk.

EBVs are currently not available for all breeds.  The Kennel Club's ability to provide EBVs is based on complex calculations, but is dependent on both:

  • The proportion of dogs scored in a breed
  • The spread of those scored dogs across each pedigree

Therefore, currently, EBVs are only available for breeds with a large number and wide spread of tested dogs.

EBVs are available for the:  Akita, Bearded Collie, Bernese Mountain Dog, Border Collie, English Setter, Flat Coated Retriever, German Shepherd Dog, Golden Retriever, Gordon Setter, Labrador Retriever, Newfoundland, Rhodesian Ridgeback, Siberian Husky, Tibetan Terrier and Rottweiler.

For further information on other health considerations to make prior to breeding, please see our 'Breeding for Health' information guide (PDF).

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