(l-r) Speakers: Dr. Kathryn Mellersh (Senior Canine Geneticist at the Animal Health Trust).
Dr Jeff D Sampson (Kennel Club Canine Genetics Coordinator.
The Staffordshire Bull Terrier Breed Council Genetics Sub-Committee who attended the Seminar: Clare L ee, Ivor Keyes, Lesley McFadyen and Archie Bryden
The first of two seminars, organised by the Genetics Sub-committee of the Breed Council GB and NI, entitled ‘DNA Testing for the SBT - the Way Forward’ was held on Saturday 21st January at Over Hulton Conservative Club, near Bolton. The audience of over sixty, including a few Boston Terrier fanciers, heard two very informative and challenging presentations by Dr Cathryn Mellersh of the Animal Health Trust and Dr Jeff Sampson, the KC’s Genetics Co-ordinator.
Following introduction by Ivor Keyes, who has been the main link between the breed and the AHT, Dr Mellersh, who is involved with all the genetic tests for conditions affecting many different breeds, commenced proceedings with a detailed look at basic genetics, chromosomes and mutations, down to the chemical units making up DNA. This was very challenging for the listener, even those with some understanding of the subject, but such was Cathryn’s skill at presenting the topic that few, if any, were ‘lost’ during her talk. She then went on to consider the genetics of the two conditions of concern in Staffords – L-2- Hydroxyglutaric Aciduria (L-2-HGA), a neurological condition causing spasms, and Juvenile Hereditary Cataract (HC). Both are caused by defective recessive genes and pedigree diagrams showing how they can go from generation to generation, possibly originating from a single dog, were presented.
Cathryn then proceeded to describe the development, and associated problems, of diagnostic tests for both these conditions. With L-2-HGA, fortune was kind to the researchers as by this time both the human and canine genomes had been sequenced and L-2-HGA had also been described in humans so it was a case of looking for a similar gene in both species. The test for HC has been a bigger problem. For several years a search, which proved unsuccessful, had been on for a linked marker test and there is no human equivalent of the condition. However, once the canine genome had been sequenced, the sensible approach of simply looking at that area of the genome involved with the eyes, and where similar conditions exist in other animals, did yield dividends and the gene responsible for HC in Staffords was identified. This gene is also the cause of HC in Boston Terriers although they can also be affected by late onset hereditary cataracts for which the genetic mechanism is as yet unknown.
The last part of Cathryn’s talk dealt with the ‘nitty gritty’ of breeding and how the conditions may be bred out, including the sensible use of carriers, without depleting the gene pool.
Following on, Dr Sampson discussed how the KC could help. This would involve the well established procedures of publishing the results of all DNA tests in the Breed Records Supplement and adding details to dogs’ registration documents. One may also get access to such results via the health pages on the KC web-site.
Moving on to the way forward, Jeff emphasised that the consensus opinion of experts worldwide, was that DNA testing should not drive breeding programmes. Breeders must consider breed type, temperament and health, equally and in no particular order – in other words look at the dog overall. As an example, he referred to how CLAD had been dealt with in Irish Setters but pointed out that dealing with the two conditions in Staffords might not be so easy. The main problem is that, unlike the situation in Irish Setters where most breeders are apparently members of breed clubs and thus relatively easy to contact, there are vast numbers of breeders registering Staffords with the KC who are not involved with clubs or the general show scene. Consequently they are not so easy to contact and influence. In an effort to counter this, it is hoped to post a ‘mail-shot’ to all who have registered litters in recent years, informing them of the new developments and the need for responsible testing.
An extremely lively discussion ensued. This dealt with questions asked, via e-mail, by overseas fanciers who are concerned about getting their own dogs tested and similar problems although much of these had been already covered. The most emotive and heated topic was the use of carriers and it must be quite bewildering for those who have previously preached against their use to be told they can now use them, albeit wisely with the appropriate testing. Both speakers were quite emphatic on this point, stressing that carriers must not be formally withdrawn from breeding programmes, although all recognise some may choose not to use carriers under any circumstance and no one is likely to use them if a suitable alternative exists.
Cathryn Mellersh, stressed, most eloquently, the self-evident elementary point that if you take genes out of the pool they are lost for ever and cannot be recovered, demonstrating how a gene pool may be decimated by successive removals. Perhaps the need to preserve a breed’s gene pool was emphasised best by one of the Boston Terrier visitors – this lady told how disastrous the removal of carriers of the late-onset cataracts had been for that breed. This allowed the early onset form to become more prevalent simply because breeders had to go in a different direction and resulted in a ‘terrible mess’!
The seminar finished with Mrs Laureen Williams, a well known breeder from the North East, presenting Dr Mellersh with a cheque for £300 for the AHT. These monies, raised by a group of collaborating breeders, came from donations, some from overseas, and from the sale of car stickers promoting the use of the new tests. A point that is often overlooked is that the AHT, with whom we enjoyed such successful collaboration, is, in fact, a charity but sadly does not have the high national profile, and consequently income, of those animal welfare organisations with a higher profile.
The second seminar will be held this Saturday, 28th January, at Hillside Hall, Abbots Langley, Herts. Anyone wishing to attend should contact Lesley McFadyen, tel 01205 871762.