PRA rcd4 update

[Gillian Kennedy-Sloane]

Following a meeting between Professor Ed Hall, Chairman of the Breed Health Committee, Dr Cathryn Mellersh. Canine Genetics Research Group Leader from AHT and Dr Jeff Sampson, Genetics consultant to the Kennel Club we have been advised by Ed Hall that in addition to the 7 dogs which have been identified with PRA rcd4 there are 3 more having "mid-onset" PRA and which do not have rcd1 or rcd4. 

Any Irish Setter with suspected sight problems can have DNA testing free-of-charge if the sample sent to the AHT is accompanied by a certificate from a veterinary ophthalmologist confirming PRA       ( Progressive Retinal Atrophy).

To get your dog tested for PRA by an ophthalmologist you will need to see your vet first and ask for a referral to an eye specialist.

[Dee Rance]

This is great news...for us that are/were clear of PRARcd1 and seeminly clear for perhaps Rcd4 it was going to cost me £60 to have my Jasmine tested for this (I would have paid this to help the breed)...Thanks to all concerned...now will have to go find the letter from Prof. Peter Bedford...

[eva ciechonska]

Oh no not another one!  Diana Van Der Valk did mention other forms of PRA and the need for regular eye testing, which is mandatory in Holland. 

Is there more information about "mid-onset" PRA? 

[Gillian Kennedy-Sloane]

  Eva:

 The  information we have is what the AHT released in their announcement on the PRA rcd4 test

 

Other Forms of PRA

The research we have carried out to identify the rcd4 mutation has revealed that there are at least three forms of PRA segregating in the Irish Setter; rcd1, rcd4 and an additional, third form, that has yet to be identified.  We know there is a third form of PRA because of the ten dogs with LOPRA, whose DNA we have been sent to analyse, only 7 have two copies of the rcd4 mutation.  The remaining 3 dogs do not carry either the rcd1 or rcd4 mutations, meaning their PRA must be due to another, as yet unidentified, mutation.  There is some evidence that this third form of PRA has, on average, an earlier age of onset than rcd4, but we need to examine more dogs before we can be confirm this.

The age at which dogs with the rcd4 mutation develop PRA seems to vary and we know about dogs as young as 4yo and as old as 10yo, that have been diagnosed with LOPRA, and that carry two copies of rcd4 mutation.  But it is important to remember that the age at which a dog is diagnosed with PRA can vary according to circumstances, and is not necessarily the same age at which it started to develop PRA.  For example, a dog whose PRA is detected at a routine eye examination will have an earlier age of diagnosis than a dog whose PRA was only detected once it started to lose its sight.  It is also possible that the dogs that have developed PRA very early also carry the mutation for the third, unidentified, form of PRA (as well as rcd4) and it is this ‘mid onset’ mutation that has caused them to develop PRA at a relatively young age.  More research will be required to understand the variability in age of onset more fully.

Our research indicates rcd4 is a common form of PRA among Irish Setters and the development of this test therefore enables breeders to slowly decrease the frequency of an important form of PRA in their lines.  However, because we know that at least one other form of LOPRA exists within the breed, we cannot guarantee that any dog will not develop PRA, even if they are clear of the rcd4 mutation.

[eva ciechonska]

I too thank you for the clarification.  It seems that we have a bit of an uphill struggle but take heart that we have 2 DNA tests for PRA which we can avail ourselves of and hope identification of the third form will not be in the too distant future.  It is worrying though that IS who have successfully vaulted over two hurdles can still potentially come unstuck on the third!!

It seems now that the recommendation is to additionally test hereditary clear stock for PRArcd-1 and CLAD after one generation.  I think I will just open an account with the AHT!!!!  

 

[lyn hathaway]

what fantastic news and well done animal health trust.

this goes a long long way in helping the breed .

its just so sad they have found others but through having regular eye checks and free dna if there is a problem im sure it can be eradicated quite soon 

[Dee Rance]

I don't think there is yet, (a DNA test) but if more dogs are tested then we may find out just what was wrong with the other dogs...one of mine included...she started going blind at the age of about 2 years and she was almost totaly blind in her left eye, and only had a small amount of sight in her right eye (at the age of 10)...it is the time just before total blindness that the stress is highest in the dogs concerned...I suspect Layla was the same Lyn??? when she went through the last stages of her distressing problem...I just hope now we can finally get this under controle..god willing....everyone should be tested....even if you aren't going to breed your dogs. And the beautiful Layla can at least rest easy knowing what exactley is wrong with her...she is such a wonderful lady....you have done such a wonderful job with her Lyn...you should be so proud of her....I know that you are.... 

[lyn hathaway]

yes dee layla did have quite a few problems in the latter stage been very disorientated bumping into things she previously kept going round it really frightened me as i thought it was always going to be like that.

shes different now very confident and as adapted fantastically .you wouldnt know there was a problem if she didnt have cataracts (saying that before cataracts she had illuminous green eyes she looked like an alien)

shes so special to me was before but more so now and dee im so proud of her 

[Dee Rance]

And yes I agree it is terrifying watching them bumping into things...Jas was still at this stage, unfortunately, and there really isn't anything that you can do for them they just have got to find things out for themselves. And that is hard...

But like you I was so very proud of my girl...you know how would people think if their kids started to go blind....would they just say, don't worry about it it doesn't hurt them, and you must stay possitive...and that will make it all OK???? I very much doubt it...and some of us (who's kids have flowen the nest) have got our dogs as 'family' so it is very hard...I know that dogs aren't 'humans in hairy coats' but they are our familys, our hobbies and our friends....and it hurts when they go blind..it hurts a lot...

[Gillian Kennedy-Sloane]

Sue:

This is the second form of LOPRA we have been told about and no there isn't a test which is why we need more owners to let the AHT know if their Irish Setter has LOPRA (Late Onset PRA) as it has been called if it was not the very early form of rcd1.