Cavalier club hears presentations on genetic diversity, EBV and MRI scans

12/06/2013

THE UK and the European methods of scanning Cavaliers and recording and disclosing results formed part of presentations made to members of the Cavalier King Charles Spaniel Club recently.
  The speakers were Dr Paul Mandigers, a veterinary specialist in neurology and companion animal science at Utecht University, and president of the Belgian Toy and Cavalier Club, Arnold Jacques, who is also a member of the scientific committee of the Belgian Kennel Club.
  Dr Mandigers spoke about the chiari malformation and syringomyelia (CM/SM) in toy breeds, and said the TV programme Pedigree Dogs Exposed had caused panic at all levels ‘from the Government, Kennel Club, breeders and clubs’. This had resulted in some poor decisions being made hastily, he said.
  A goal should be ‘to get away from scanning’, he said, adding that MRI scans might be incorrect, and that publication of scan results was dangerous and should be avoided because it encouraged ‘naming and shaming’, which was ‘not healthy’.
  The European scheme of scanning does not require disclosure of results.
  The results of scans for SM and CM were published for the first time by the KC in 2012 when, amid concern on the part of Cavalier breeders, the British Veterinary Association (BVA) and the KC agreed to forge ahead with an official health scheme.
  Attempts have been made to put Cavalier estimated breeding values (EBV) in place since 2007, but the subject of SM in the breed has been the cause of much unrest since Pedigree Dogs Exposed was screened in 2008. Some breeders are not keen to have the scan results recorded on their dogs’ registration documents and want them to show only the date of the scan.


Standard change

Mr Jacques told those present that to maintain genetic diversity it was important to integrate colours and widen the gene pool, and the Cavalier club is to ask the KC to change the breed Standard so that white is no longer ‘undesirable’.
  Dr Mandigers stressed the need for scientists and breeders to work together on health issues affecting the Cavalier, explaining that he had looked at 866 scans between 2002 and ’12, including clinical cases, and then re-evaluated the same scans using the KC/BVA CM/SM scheme protocol for the European scheme. After studying data from more than one breed he had concluded that CM and SM could be two separate conditions.
  "At least, this is the case in breeds such as the Chihuahua and French Bulldog,” he said. "Most likely it is also the case with the Cavalier.
  "But as virtually all Cavaliers have CM it is difficult to distinguish.”
  All breeding stock should be scanned for SM, he said, but the ‘baby should not be thrown out with the bath water’.
  "We are currently still not able to define our true sick animals from our true healthy ones,” he said. "All aspects of health should be considered.”
  Although one would never choose to breed from a dog with symptoms of SM or a young dog with a heart murmur, he said, one may need to breed from a dog ‘with not such a good scan’ but which comes from a good heart line, ie where parents/grandparents, are over the age of five with clear hearts.
  A syrinx – which causes syringymyelia – results when cerebrospinal fluid, which normally flows around the spinal cord and the brain, collects in a small area of the cord and forms a pseudocyst. In the case of SM, the syrinx can expand and elongate over time, destroying the spinal cord. Having studied scans, Dr Mandigers said, when the syrinx was round in shape and cerebrospinal fluid could surround it he had seen no signs of pain or other symptoms.
  Where the syrinx was irregular in shape and the cerebrospinal fluid was unable to surround it the dog would experience pain and show symptoms of SM, he said.


Careful breeding

"This may mean, in fact, that these dogs are not only clinically different but may also be genetically different,” he said. "We still do not know.”
  The number of Cavaliers affected by SM is a small percentage, he said, and with careful breeding the condition could be eradicated.
  "In the Netherlands, the breeders have been scanning since 2002 and we have seen a clear drop in the number of affected animals as the years go by,” he said. "The selection does work.”
  Dr Mandigers talked about the shape of the Cavalier’s skull and its relation to CM/SM.
  "There might be some relation but it’s not as simple as that,” he said. "A recent study done in Germany showed there was a relationship between a specific narrowing of a small skull foramen and SM. That’s why we need to have as a primary objective to define our phenotype correctly.
  We need to find tools other than scanning, such as a molecular test,” he said. "Currently we are only doing MRI scans and this might be incorrect.
  "Maybe we need to also use a CT scan to define true sick dogs from the others. The more dogs we can use the better it will be. And maybe we are now too strict.”
  However, Clare Rusbridge, a specialist in veterinary neurology, said that as universal MRI scanning was not required in the UK and many other countries, breeders of dogs susceptible to SM could choose which animals to scan and which results to send to the European scheme.
  The European scheme accepted images from unofficial MRI reporting schemes, she said, which might not be of the same standard as that of the BVA/KC scheme.
  "The data taken out is only as good as the data put in,” she said.
  In the second presentation, Mr Jacques told those present that to ensure the future of the Cavalier a sustainable breeding policy was needed in the world of ‘quantitative genetics’. This, he said, would establish the heritability of certain traits so scientists would be able to make predictions about siblings based on the characteristics of parents, grandparents, brothers, sisters and so on.
  European experts were far further ahead than the UK in their EBV programme, he said, and so impressive had been the work done that they had received Flemish government support with a grant to develop a Mate Select-type programme based on EBV calculated from all types of health screenings, including DNA tests, eye tests, MRI scans, cardiologist reports, to offer a reduction of the inbreeding coefficient.
  In the UK, the Animal Health Trust (AHT) has received funding from the KC to help develop its EBV programme. Currently, it is able to look at data provided from the KC/BVA schemes with regard to CM and SM, heart problems, dry eye/curly coat and episodic falling, he said.
  To build a sustainable breeding programme, close collaboration was needed between breeders, breed clubs and the scientists, he went on. Measures imposed ‘from the top simply did not work’, he said.  Instead, breeding policies should be developed in close collaboration between the various parties, otherwise each initiative, however good, would be ‘doomed to fail’.
  Following Mr Jacques’ suggestion, the Cavalier King Charles Spaniel Club made a formal request to the KC to look at its pedigree database for Cavaliers. The European study already has the pedigrees of 125,000 Cavaliers, Mr Jacques said. 
  "We have to work in collaboration with Europe and encourage the experts to work together,” he said.
  The thrust of Mr Jacques’ presentation was the need to maintain genetic diversity, and he highlighted that, particularly in Europe, particolours and whole colours are treated almost as two separate breeds in breeding programmes.  By integrating the colours the gene pool instantly widens, he said.
  However, in order to encourage breeders to ‘take the risk’ and produce whole colours with white, the breed Standard would need a very slight adjustment. In the UK this breeding had been done occasionally to improve the quality and type, and stock mismarked with white are kept to breed on the next generation. In Europe this is not possible, Mr Jacques said. The Cavalier was an English breed and, therefore, under FCI rules the English breed Standard has to be applied strictly. Therefore, all breeding stock is assessed prior to any breeding, and a whole colour with white would not be permitted to be bred from.


Changes to Standard

Following this presentation, the Cavalier Club gave its support by proposing to all regional clubs that changes are made to the Standard so that references to ‘white undesirable’ are removed from the whole colours, and  the words ‘broken up’ in the phrase ‘black and white well spaced, broken up…’ removed from the particolours.
  The KC’s health and breeder services manager Bill Lambert, who was present at the talks, said that if the majority of Cavalier clubs gave their support to the revision of the Standard the KC would be ‘highly likely’ to make the changes. "How much more attractive than outcrossing!” he said.
  Chairman of the Cavalier King Charles Spaniel Club, Sheena Maclaine, said: "It is very important that the right dog for the right bitch is selected based on all its health factors and not just one. It was great to hear this from one of the world’s leading experts – a message that humble Cavalier breeders had failed to get across at meetings with the KC and BVA experts in scheme planning meetings.”
  Following the presentations, club members had their say. Elaine Waddington, former health representative Northern Cavalier King Charles Spaniel Club, said:
  "Dr Mandigers’ talk on CM/SM was enlightening with some new ideas being delivered. The sharing of research between countries will help to ensure a more balanced view and can only be helpful.
  "I left the meeting feeling more positive that there was hope that our beautiful breed could be saved.”
  David Crossley, health representative of the Humberside club: "It was good to hear European scientific views based on fact and not personal theories.”
  Rob Dix, the KC’s breed liaison and health liaison representative: "Dr Mandigers’ presentation was so well received because he told us that some of the other leading experts’ theories may well be wrong, and that there was a considerable amount of tunnel vision. It felt like, at last, there was some challenge to existing theories backed with sound science.”
  Afterwards, Dr Rusbridge said the European EBV was an excellent scheme, ‘potentially’.
  "In the Netherlands there is a requirement for 100 per cent participation, and all Cavaliers must be scanned twice in their lifetime,” she said. "Its all-inclusive policy means that it has the potential to be a very useful tool for Dutch dogs.  
  "However, universal MRI scanning is not required in the UK or in many other countries which means that, potentially, breeders of dogs susceptible to SM can be selective about which animals to MRI and which scan results to submit to the European scheme.
  "I am also told that the European scheme will accept images from unofficial MRI reporting schemes which may or may not be the same standard as the BVA/KC CM/SM health scheme. Because of this selection bias and the very human temptation to submit only good results the EBV results may be biased for UK and other international dogs – the data taken out is only as good as the data put in.  


Peer-reviewed

"Also, there is no way that the puppy-buying public can confirm if the breeder is making sensible breeding choices, ie, what is to stop the breeder saying that they are MRI scanning and are using this scheme when they are not? In contrast, the UK’s BVA/KC CM/SM health scheme allows anyone to search for a dog and its results on the KC website and receive the reassurance that parent dogs were indeed scanned.
  "Of course, I respect and welcome that Dr Mandigers has an alternative viewpoint. Different theories and research approaches are the way that advances are made in science and I look forward to him further supporting his comments by the publication of peer-reviewed research, which can then be considered by the full research community.”
  Mrs Carter said she was surprised by the enthusiasm with which the concept of EBV was greeted by those at the presentation when ‘the Cavalier Club website shows that EBV were first introduced to Cavalier breeders in May 2008’. 
  "Also shown on the website is a series of appeals from the club for breeders to send in health information to geneticists at the AHT,” she said. "Although there are already EBV for health problems in some breeds, the limited information actually provided by breeders caused the UK scheme for Cavaliers to falter. The AHT is now waiting for enough reliable, standardised information to come through from the new BVA/KC CM/SM scheme. Unfortunately many breeders are boycotting it.
  "Over the last year there have been many questions asked about the reliability of the European EBV scheme when those promoting it are requesting breeder-selected health certificates for dogs with no permanent identification, produced by different vets and specialists using very different standards.
  "The European EBV are part of a larger four-year project, and work to include UK dogs cannot start unless the KC agrees to allow access to their Cavalier registration database. Accurate EBV could be produced by the AHT in a much shorter time by breeders supporting the official BVA/KC schemes but, of course, that does mean that all health test results will be available to puppy buyers. Publication of results is something that many breeders wish to avoid.”  
  Mr Jacques’ suggestion that the mismarked clauses in the breed Standard be removed to boost genetic diversity was a sensible one, Mrs Carter said.
  Ms Rusbridge’s and Mrs Carter’s comments were put to Mr Jacques who said that an international team of experts including Dr Mandigers, who specialises in SM/CM, is to study the pedigrees of Cavaliers. The next step will be to collect data on the health issues facing the breed, and Dr Mandigers is currently reviewing ‘hundreds’ of MRI scans.
  "There have been many questions asked by British people, but I always tell them to be patient,” he said. "We can’t build a sustainable breeding programme in a few months, and we cannot afford to make statements that we have to recall later on.
  "As soon as we have made the decisions, we will communicate them.”
  Mr Jacques and Dr Mandigers will speak again and answer questions the day after the club’s ch show on March 2 at the KC Building at Stoneleigh. All the other clubs will discuss the proposals and give the Cavalier King Charles Spaniel Club their views.
The full content of the presentations is available at www.thecavalierclub.co.uk.


 

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