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PRA and the Glen |
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****** BOCHUM PRA RESEARCH PROJECT ******
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Progressive retinal atrophy (PRA) is an inherited eye disease, now known to affect some Glen of Imaal Terriers. Affected Glens will eventually lose their sight. |
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This page looks at progressive retinal atrophy and the Glen of Imaal Terrier, and explains the rationale for eye testing. General information about PRA and its mode of inheritance can be found on the Progressive Retinal Atrophy page, together with a table illustrating basic breeding outcomes. The PRA Pedigrees page discusses breeding issues concerning the Glen and PRA. To continue reading this page, please click on the links below or scroll down the page: |
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Written: Sept 2003
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The first case of PRA in Glens was diagnosed in August 1996. Since then, responsible breeders have established a programme of regular testing of their Glens. All Glen owners, whether they have pet Glens, show Glens, working Glens or breeding stock, are urged to have their dogs tested regularly. An international database has been set up to monitor the results. |
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In July 2001, a young Glen aged 2 years and 2 months had an eye examination with "suspicious" findings. Six months later, he was re-tested and a diagnosis of PRA was confirmed. |
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Since then, in 2005, we have had a another Glen with a definitive diagnosis of PRA at 2 years and 2 months of age. |
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In April 2004, another Glen aged 7 years and 10 months had a diagnosis of PRA confirmed at her eye examination. She had been regularly tested "clear" prior to this, with one "suspicious" test result before confirmation of the diagnosis. |
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The examination |
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The difficulty with PRA is that there is currently no test to determine a Glen's genetic status i.e. we cannot do a simple blood test to identify whether a Glen is normal, a carrier or affected. For the time being, we have to rely on eye testing by a veterinary ophthalmologist. Eye testing can identify affected Glens. However, a "clear" test result cannot differentiate the normal Glen from the carrier Glen or even the Glen who goes on to test affected at a later date. |
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Eye examination should be carried out by a certified veterinary ophthalmologist. Your dog will be given some eye drops, to dilate the pupils. After about 20 minutes, your dog can be examined. The examination takes place in a darkened room; the vet will look into your dog's eyes using an instrument called an indirect ophthalmoscope. This examination takes just a few minutes, and is a non-invasive and painless procedure for your dog! |
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You need to bring your dog's registration documents with you when you have your dog's eyes tested. The veterinary ophthalmologist will issue you with a certificate, valid for one year, detailing his/her findings. |
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Eye testing sessions |
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Many national breed clubs organise eye-testing sessions at their shows. In the UK, the two weekly dog papers, Our Dogs and Dog World, list eye testing sessions around the country. Our Dogs - click on "Show Calendar" and then go to "Eye testing & microchipping" Dog World - click on "Dog Man's Diary" and then go to "Health and eye testing" |
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Professor Peter Bedford and Dr Gregory Acland both have a special interest in PRA in Glens. They conduct the eye-testing sessions at the Glen of Imaal Terrier breed club shows in the UK and USA, respectively. N.B. You don't have to enter the show to have your Glen's eyes tested. Contact the organisers to request an appointment for the eye-testing session. Contact details can be found on the GOITA (UK) and GITCA (USA) club websites. |
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Costs |
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The cost of eye-testing at breed club shows and events in the UK is relatively inexpensive, up to £20.00 per dog. GITCA (Glen of Imaal Club of America) request a discretionary fee of $25.00, (members and non-members), which is donated to Dr Acland's research fund at Cornell University. |
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If you are unable to attend any of the eye-testing sessions at club shows and events, contact your nearest database co-ordinator (below), or your vet, and they should be able to help you locate a specialist veterinary ophthalmologist. N.B. A "private" eye-testing session will cost you a little more. |
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Reporting of results |
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A database (see below) has been established to record and monitor all eye test results. All Glen owners and breeders are encouraged to submit their Glens' eye test results to their nearest database co-ordinator (below). |
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As Glen owners, I feel that we all have a responsibility, both to the breed and to the breeders, to undertake regular eye testing of our Glens. Think of each eye test result as a piece in a jigsaw puzzle; the more pieces we have, the more sense we can begin to make of the bigger picture. Inevitably, the more Glens that are tested, the more information the breeders will have to enable them to make their breeding decisions. |
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PRA in Glens is thought to be "late onset" i.e. it is very unlikely that a Glen would show any degenerative changes (at eye examination) as a puppy. There has been some debate as to [i] how often testing should be carried out, [ii] at what age we should start testing our Glens, and [iii] up until what age should we be testing? |
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In the light of what we know to date - see History of PRA and the Glen (above) - it would seem sensible to start testing by 2 to 3 years of age* and continue with annual testing until at least 8 to 9 years of age. It is also suggested that the owners of all older i.e. over 9 years of age, non-tested Glens, arrange a "one-off" eye examination for their dog(s), for the database records. |
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Professor Bedford, a veterinary ophthalmologist with a particular interest in the Glen, recommends that breeders have their litters routinely screened for congenital and hereditary eye anomalies. He suggests annual screening thereafeter. |
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A three-part international database has been established to record eye test results and monitor the incidence of affected animals within the breed: |
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Tested Glens
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Glens that have tested "clear" and are
not known to be carriers.
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Please notify your nearest database co-ordinator of the results of your Glen's eye test: |
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UK
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Jean Rogers
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jean@e-f-g.co.uk
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The minimum information required for the database is detailed in the table below. Your database co-ordinator will advise you where to send a copy of the eye certificate. |
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Your Glen's full kennel name |
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Date of birth |
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Date of test (month & year) |
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Please indicate: Tested "clear" (i.e. no clinical evidence of PRA) OR Tested affected |
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Sire's (father's) kennel name |
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Dam's (mother's) kennel name |
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I believe that "reputable and responsible breeders" [i] have their Glens checked annually by a certified veterinary ophthalmologist and [ii] try to minimise the risk of producing Glens that will develop PRA (and eventually lose their sight) by making informed and considered breeding selections. |
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To help you decide which breeder, here are some questions that you might like to ask: |
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1. |
Have both the dam and the sire of the litter had their eyes checked, and certified as "clear", by a certified veterinary ophthalmologist within the last year? |
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All Glens, and especially breeding stock, should have annual checks. Certification of "clear" results is only valid for one year from the date of examination. Ask to see the certificates, which will detail the date of examination and the findings of the examiner. |
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Have all four grandparents of the litter had their eyes checked, and certified as "clear", by a certified veterinary ophthalmologist within the last year? If any are over eight years of age, have they had a "clear" test since they turned eight? |
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The breeding ethics of any breeder buying in, and using, a Glen with untested parents should, in my opinion, be questioned. In effect, these breeders are: |
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[i] |
using Glens with no "history" - so how can they give you any idea of the possibility, or not, of your Glen ever developing PRA and losing its sight in the future? |
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[ii] |
condoning the irresponsible breeding practices of the breeders who don't bother to test. |
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Eye testing has been established within the breed for long enough now that any Glen being bred from should have tested parents i.e. the parents and grandparents (at least) of any litter born now should all have up-to-date eye test certificates. |
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What is the "PRA status" of the parents and grandparents? |
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Ask the breeder to identify untested Glens, affected Glens and any known carrier Glens in the pedigree. Also ask if any of the others have affected or carrier litter siblings (brothers and sisters) e.g. in the absence of any further information, litter siblings of known carriers have a 50% chance themsleves of being a carrier. |
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Affected Glens should not be used in a breeding programme, if (as with the Glen) there is no genetic marker available. There is currently no concensus of opinion within the Glen community regarding the breeding of known carriers. |
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Just because a Glen tests "clear" doesn't mean that it won't produce Glens that go on to develop PRA e.g. the mating of two known carriers (both of which will test "clear") will produce puppies that each have a 25% chance of developing PRA. This is why it is important to ask not only about the latest eye test results, but about the PRA status as well. |
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4. |
What chance does each puppy in the litter have of developing PRA? |
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The fewer affected and carrier Glens in the pedigree, the less likely it is that a Glen will develop PRA. (The PRA Pedigrees page takes a detailed look at various different breeding scenarios and outcomes). |
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How old was the bitch when she was mated? |
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This is a rather more controversial issue and there is no consensus of opinion regarding the age of first mating of dogs. However, there are breeders who would agree that, as the youngest age at which PRA has been diagnosed in Glens is two years and eight months, it makes sense to wait until at least that age before first breeding from a bitch. The bitch should, of course, have had a "clear" eye test result at or after the age of two years and eight months. (The PRA Pedigrees page discusses age of first breeding in more detail. See under 'INTRODUCTION' and 'At what age should a Glen first be bred from?'). |
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Remember: Any Glen, whatever age, should have had a "clear" eye test result within the year prior to any breeding. |
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Those breeders who do not have their Glens tested would probably argue that PRA is not a life-threatening disorder, so why bother? However, it is generally accepted, by both the veterinary profession and many breeders, that it is "good practice" to screen for any hereditary disorder that has been identified (and recognised) in a breed, with the aim of reducing the incidence of affected animals within that breed. This cannot be achieved without a committment to regular testing. |
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The owners and breeders who have Glens diagnosed with PRA will tell you that the news comes as an awful shock because, very often, they have not yet noticed any signs that their Glen's sight is failing. Inevitably, the quality of life of an affected Glen, as its sight deteriorates and eventually fails, will be compromised. |
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Why "breed blind"? (No apology here for the pun). This is what, in effect, some breeders are doing. So, even if it means waiting a little longer for an eagerly anticipated puppy, I would urge Glen puppy buyers to support those breeders who: |
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[i] |
undertake regular testing of their animals; |
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[ii] |
are "open" about the PRA status of all Glens in the pedigree; |
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[iii] |
wait until their bitches are nearer three years of age (or older) before first breeding from them. |
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Progressive Retinal Atrophy
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PRA Pedigrees
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