THE PRACTICE of outcrossing being used to help breed away from extremes of conformation was discussed at a recent meeting of the Dog Advisory Council (DAC).
The council discussed problems caused by selection for extremes and DAC member Dr Cathryn Mellersh said the aim was to develop sound advice on how extreme conformations could be tackled.
Inheritance of most of these traits was likely to be complex, she said, and a range of solutions needed to be considered. One potential but sometimes contentious solution was outcrossing, she said, particularly when there was insufficient variation within a breeding population to make progress or make it quickly enough to satisfy everyone.
Tom Lewis of the Animal Health Trust was invited to discuss the issues to be considered, and he said the first was to understand what was meant by outcrossing, for example a breeder introducing a new line into one previously closed and/or the introduction of imported dogs of the same breed; and/or the introduction of a dog of a different breed.
He said an important starting point was to establish why outcrossing was being considered in the first place and to consider whether it was possible to achieve the necessary improvement within the existing population. In livestock, outcrossing was used commonly to gain hybrid vigour in the dam line and subsequent further unrelated crosses were used to establish the desired qualities in the end product, such as fatter lambs, he said.
No silver bullet
However, if outcrossing was used to resolve a problem in a particular breed and it resulted in variation in the progeny, breeders who desired predictability and uniformity would need to back-cross, which could result in the same limitation of variation as in the original, he said.
The key message was that outcrossing was not a silver bullet, and might resolve one problem only to create others, he concluded.
The point was made during discussion that time was needed to allow selection to be exerted at a reasonable pressure and to allow for purging of unwanted characteristics.
The KCís health and breeder services manager, Bill Lambert, said the KC was open to the idea of outcrossing, and reference was made to the programme devised to produce a naturally docked tail in the Boxer. He said the KC would consider favourably proposals from a breed club to outcross to address a health problem, particularly if based on scientific advice.
A proposal from an individual would not be ignored but was less likely to be successful because an effective programme required both critical mass in terms of numbers of dogs and backing from the breed, he said. When considering whether outcrossing might be a suitable solution it was necessary to take account of not just the actual population size but the effective population size of the breed in question, those present agreed.
The question was posed whether the use of sires in breeds of low population size should be limited, as it was said was done in Sweden. Again it was pointed out that it was effective population size which needed to be considered rather than population size, as breeds which produced large litters could be numerically large but still have limited effective populations.
Absolute limits were not favoured, Mr Lewis said, because variation between breeds was too great and it was better to maintain flexibility to address different cases.
DAC chairman Sheila Crispin wound up discussion by inviting people to volunteer to become part of a working group to look at the issue of outcrossing.
A single standard for breeding dogs was also discussed, and council member Chris Laurence said a working party on the subject chaired by Prof Sir Patrick Bateson had concluded its work with the differences between the Assured Breeder Scheme (ABS) standard and that of the councilís decreasing considerably.
He said the aim of the working group had been to arrive at the point where the two standards were the same. Prof Batesonís working group, composed of equal numbers of Council and Kennel Club members, had worked well under his chairmanship, he said, and had agreed a single version which will be considered by the KCís ABS sub-committee on January 8.
KC chairman Steve Dean said there had been a mix-up regarding which version the sub-committee should have been looking at, but that this had been sorted out and progress should now be possible.
Mr Laurence said the working group had come up with a better version than that circulated originally by the DAC in that it clarified some complex issues and was generally less complicated. This shows the benefit of working collaboratively, he said.
Finance for the DACís work is still being sought. It has enough money to continue until the end of next year but not enough to pay for the projects it would like to undertake, Prof Crispin said. She thanked Dogs Trust, the PDSA and the RSPCA for continuing to support it financially; she said the Council did not want to continue to ask the same groups for help with funding and would be approaching other bodies, such as the KC Charitable Trust.