Breeding dogs on the basis of a single genetic test carries risks and may not improve the health of pedigree lines, scientists from The Roslin Institute at the University of Edinburgh have warned.

About half of all cavalier King Charles spaniels are affected by an inherited heart murmur.

Only a combined approach that makes use of DNA analysis, health screening schemes and pedigree information will significantly reduce the frequency of inherited diseases.

This approach will also improve genetic diversity, which helps to counteract the risk of disorders, the researchers say.

They made the recommendations having reviewed the various approaches being taken to minimise potential defects in pedigree animals.

Kim Summers of The Roslin Institute said breeders were keen to embrace DNA testing to improve the health of their breed.

“We need to make sure these powerful technologies are used to best advantage,” Prof Summers said.

Pedigree dog breeds are created for desirable physical and behavioural characteristics, which often stem from breeding between closed familial lines over years and – in some cases – centuries.

This approach means inherited diseases can become more common in pedigree populations. About half of all cavalier King Charles spaniels, for instance, are affected by an inherited heart murmur that can be life-threatening.

Health screening dogs before selecting animals to breed from has already helped to reduce the prevalence of some diseases, such as floating kneecap in the Dutch kooikerhoundje breed.

DNA tests are now available to help identify dogs carrying gene mutations known to cause some severe illnesses. It is hoped this technology will help eliminate disease-causing genes from pedigree lines.

But the scientists maintain ruling out breeding dogs solely on the basis of a single failed DNA test result will reduce the gene pool of pedigree lines and make inbreeding more common. It could also inadvertently increase the prevalence of other genetic diseases that have not been tested for.

They recommend limiting the use of individual stud dogs to promote more diversity in pedigree lines and cross-breeding to introduce even greater genetic diversity.

Breeding the offspring that result from cross-breeding with the original pedigree for 10 generations can produce animals that share 99.9 per cent of their genetic material with purebred animals, but lack the gene faults that cause disease.

This approach has been successful in generating Dalmatians lacking a genetic defect that causes kidney stones, which is common in the breed.

Lindsay Farrell of The Roslin Institute said although carrying a specific genetic variant might raise the likelihood an animal would suffer from the associated disease, it was not guaranteed.

“When making breeding decisions, genetic testing needs to be considered alongside health screening and family history,” Dr Farrell said.

“That will help keep as much genetic diversity as possible in our pedigree dogs and, at the same time, reduce the prevalence of inherited diseases.”

The article is published in the journal Canine Genetics and Epidemiology. The Roslin Institute is funded by the Biotechnology and Biological Sciences Research Council.

View your activity >

Leave a Reply

Be the First to Comment!

Notify of