View Full Version : AHT interim Episodic Falling Syndrome statistics
16th May 2012, 03:47 PM
Animal Health Trust reports interim statistics from its DNA study of Episodic Falling Syndrome in the cavalier King Charles spaniel. One out of five cavaliers were found to carry the defective gene.
As of May 15, 2012: 2,811 cavaliers have been DNA-tested for episodic falling syndrome, of which 104 (3.7%) have been found to be "affected" with two of the mutated EFS gene, 605 (21.52%) are "carriers" with only one of the mutated gene, and the rest, 2,102 (74.78%), are clear of the defective gene.
16th May 2012, 04:44 PM
wow, I didn't think there would be so many carriers. Do you know the months of the data collection for this last statistics? Clearly I can see why breeders need to keep the carriers in their breeding program.
Labradors have a similiar condition called Exercise Induced Collapse. Carriers are encouraged to be removed from breeding but Labrador gene pool is so much larger than the cavaliers.
16th May 2012, 05:16 PM
... Do you know the months of the data collection for this last statistics? ...
AHT starting collecting DNA samples in April 2011, so this is about a year's worth. There still are at least a hundred samples in the pipeline, yet to be examined.
16th May 2012, 05:27 PM
It's a lot higher than I would have expected.
Then again,they are interim statistics and people would have started testing to hunt down suspects.
But I hope it puts an end to the notion that carriers could or should be removed from breeding programmes.
Carriers are in fact healthy dogs,and in the hands of capable and competent breeders,can be utilised for the benefit of the breed.
16th May 2012, 05:48 PM
I would guess as well many owners had suspect EF dogs tested and had the parents tested. It could very well skew results for the worse. I would like to see numbers again in a year after CEO breeders have their breeding dogs tested.
Overall I think the DNA testing is being done so congrats to all those involved that helped with the development of the tests!
16th May 2012, 07:31 PM
I will note again that the researcher behind this, Jacques Penderis, stated strongly to me in an interview posted elsewhere here that he felt EFS was MORE common than epilepsy in the breed and he classified it as a 'common' genetic issue in cavaliers. I know as many EFS & epileptic cavaliers as I know symptomatic SM cavaliers in Ireland. My vets (a large practice with about 6 clinics) say they see both regularly in cavaliers (EFS & epilepsy, that is).
The results from such a massive sample would be very hard to skew -- initially there was such a small response for getting samples that they put out a wider call (eg to pet owners) for the free testing. So this is almost certainly a very random sample, with a lot of dogs eventually coming from breeders through club appeals. But I think there just aren't that many affected dogs for there to be anything like the hundreds and hundreds of expected carrier parents to influence the sample. Of the breeders and pet owners I know who submitted DNA for this, none had suspected EFS dogs.
I think overall it is impossible not to use carriers of CM/SM either -- that's why MRIs are probably going to remain important tools for many years and must be an expected cost with this breed. What's needed is not a DNA test simply for the condition, but a DNA test that can incorporate in what the Canadian team suspect and have found compelling evidence for -- that there is also a 'protective' gene or genes that in some dogs, prevents CM evolving into SM or into highly symptomatic SM.
Hence again why just submitting scan results that only take into account the presence of a syrinx is not adequate for DNA work in the breed -- SM is only part of the picture.
EFS and CC were far easier to isolate as they are simple inheritance genes. MVD and CM/SM are on all evidence, far more complicated.
The worrying thing is how many potentially serious health issues there are in the breed, with MVD an almost-certainty in all dogs and so widespread in early onset form that it skews life expectancy, and CM almost all dogs, and SM the majority. The situation is so severe that I think anyone with a supposed CM free dog has a moral and ethical obligation to submit the scan to at least one of the BVA/KC panel neurologists for a second opinion. Such dogs are just too rare, and too many neurologists are poor at reading for CM.
Right now cavaliers have a lot of bullets to dodge. :(
16th May 2012, 07:35 PM
From my interview last year:
It turns out the condition is caused by a simple recessive trait, which makes it much easier to exactly locate and also easier to address, as well as easier to create a genetic test. Basically, breeders will be able to test to see whether any dog carries the gene for EFS. By eliminating dogs with the gene–or at least initially breeding dogs with the gene to dogs without the gene iF a wider gene pool is needed, as is probably the case as he describes this as a 'widespread' condition, both internationally and within the breed generally–gradually the incidence will drop and the condition could be entirely eradicated.
He said the gene involves the brain, and this is definitely not a muscular disorder (he said one paper was published that erroneously stated this a while back, but it is clear this is not the case). he said the gene is a quite interesting one, and that it has not in the past been known to be involved with genetic conditions, and the discovery may be of help in human medicine. But he could not give me any detail because the results are not yet published.
He also noted that he would define episodic falling as a *common*, not a rare condition in the breed. He said the incidence of EFS would be much higher than of epilepsy, for example–he would consider cavaliers to be “moderately” affected by epilepsy. He also said the vast majority of cases are very mild, with many stabilizing by age 1. He said it is actually quite rare for cases to be severe or to require a dog to be euthanized.
We split the hour pretty much evenly between EFS and SM. Some of the key points that I found interesting during our discussion on SM was his observation that they see almost no other breed than cavaliers coming in with SM, and he thinks it is actually quite rare in other breeds, including the toy breeds/brachycephalic dogs. He says they do not even see it as an occasional incidental finding when doing MRIs on other breeds, whereas they would commonly find CM and often SM on any cavalier MRI. He said he is not sure why one center in the US has seen up to 40% of its SM caseload in other breeds, and wonders if this is due to a local problem in certain US populations of breeds. he noted yorkies are one breed they see with SM as well.
He also would be quite conservative on choosing whether to do surgery– he feels surgery is something to consider after medication fails, or in young severely affected dogs. He said he did not feel there was any outstanding evidence so far that surgery is a better choice than medications and notes existing studies are more about anecdotal evidence on whatever approach a given team is doing. (This is true–there has been no proper comparative study.) He also noted, however, that perhaps there were benefits to doing surgery when affected dogs were young, before their syrinxes have a chance to expand and cause damage.
He is quite convinced that the problem of SM and many of these other neurological issues lies in the shape of the cavalier skull; he said some "extreme" internal feature not yet identified that has been bred in which now sometimes causes serious problems inside the brain and the spine as a result, amd a high degree of CM/SM ( though he uses the terms Chiari malformation and syringohydromyelia himself). He emphasized (as have other researchers) that this has nothing to do with the outward shape of an individual skull or head but has to do with the fact that the dog is generally in the brachycephalic category and that there is some *internal* element affected by this particular type of skull in this particular breed. he noted that there are neurological conditions known throughout the brachycephalic breeds.
He encouraged breeders to continue to scan and submit scans and DNA As the only way forward for addressing SM, which he described as a more serious and difficult problem than EFS. He said that it may be in future that the Cavalier will be pointed to as one of the healthier breeds because with breeder support, some of its genetic problems will have been identified and breeders will have the tools to breed away from these neurological issues.
He also noted that he felt it was beneficial that different researchers approach these health issues from different directions and with different ideas, including treatment ideas, because this is more beneficial in trying to understand and resolve the problem. in that sense, he indicated it would be quite counterproductive for every researcher to have a common agreement around these health issues. The fact that many people have had many ideas has helped already to eliminate some ideas and hone in on others.
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