THE BASSE​T GRIFFON VENDÉEN CLUB
OF GREAT BRITAIN

EYES

BGVs' EYES     

In 1996, a PBGV imported into England from France was tested and found to have Primary Open Angled Glaucoma.  This was the first known case in the UK.  It set in motion many years of intense effort and liaison between the BGV Club, Peter Bedford Professor of Veterinary Ophthalmology and the Animal Health Trust in researching and attempting to eradicate this eye disease from the breed.  Regular eye testing and now DNA testing play a large part.  There has been no indication of the disease in GBGVs.   

WHAT IS GLAUCOMA?       

PRIMARY GLAUCOMA is an inherited canine condition.  It is sub-divided into two types - Open Angle Glaucoma (POAG) and Closed Angle Glaucoma (PCAG).  In both forms glaucoma results from reduced drainage of fluid within the eye, causing a build up of pressure and damage to the delicate structures within the eye.  This in turn leads to pain and probable blindness.    

Closed angle glaucoma  This type of glaucoma is more difficult to detect as the problem occurs further down in the eye structure and pressures can be OK one day and escalated the next.  It is more complex than POAG and may involve more than one type of mutation making it harder to find in the canine DNA.  Although rare, during the screening process of PBGVs, Primary Closed Angle Glaucoma has been found.

Open angle glaucoma is a disease in which the cells that produce sight in the retina are destroyed by a slow rise in the internal fluid pressure in the eye. Normally this fluid, known as the aqueous, is constantly produced inside the eyes to feed the lens and the cornea. It is drained from the eye back into blood vessels and the production and drainage rates are balanced.  In POAG it is a disturbance of drainage which leads to an accumulation of this fluid and hence the pressure rise. The sight gradually diminishes and, as the fluid pressure increases, the eye enlarges and the lens may dislocate. Eventually the dog becomes blind.     

EYE TESTING    

The British Veterinary Association/Kennel Club Eye Scheme offers the facility of eye testing to screen for inherited eye disease.  Anyone can use the information to eliminate or reduce the frequency of eye disease being passed on to puppies and, importantly, it gives early warning where treatment may be needed to delay onset.    Although any breed can be examined for eye disease, currently only the results of those breeds that appear on a Kennel Club list (Schedule A) have these included on the KC computer records and published in the KC Breed Records Supplement.  The eye test certificate records any possible problems and, importantly, whether a PBGV that has been Genetically diagnosed by DNA test as having POAG is Clinically Affected or Clinically Unaffected at the time of eye testing.  These eye test results for any PBGV affected by POAG may change from one test to the next, depending on whether the eye drops used are keeping the pressures under control.​  
Put simple this means:   
CLINICALLY UNAFFECTED        EYE PRESSURES SATISFACTORY AT TIME OF EYE TESTING                    
CLINICALLY AFFECTED              EYE PRESSURES RAISED AT TIME OF EYE TESTING    

Message from Peter Bedford: "Undoubtedly there is evidence that Open Angle Glaucoma is inherited. This disease is difficult to manage because it is often silent in its approach and, by the time the diagnosis is made, the dog's sight is badly affected and the eye may be enlarged. Once the process starts it is almost impossible to control. The earlier the diagnosis, the better the chance of effective treatment   

EXPLAINING THE EYE TESTS        

BACKGROUND    

As several factors were involved, for many years the BGV Club in collaboration with Prof Peter Bedford concentrated on abnormal anatomy in the drainage angle and subtle pressure rises in the eye.  They therefore encouraged two types of eye testing - gonioscopy and tonometry.  Only tonometry is now needed.    

GONIOSCOPY   (The abnormal anatomy).  

This is an eye examination, separate from the routine one carried out under the BVA/KC/ISDS Eye Scheme.  It is done to detect glaucoma predisposition, or how likely the eye is to develop glaucoma.  This test only had to be done once in a PBGV's lifetime, from 4 months old onwards.  It ensured the angle was open and provided information on what is generally described at pectinate ligament dysplasia.  For POAG the angle is not abnormal in clinical appearance in affected dogs and the advent of DNA testing early 2015 rendered this test unnecessary.    

TONOMETRY   (The pressure).  

This BVA/KC/ISDS regulated test, which still takes place for PBGVs, measures pressure within the eye and out-flow pressure.  It aids early identification of problems such to POAG, Progressive Retinal Atrophy and Lens Luxation.  It is ideally done annually, preferably up to the age of 9.   Twice a year is advisable and, if a dog is related to a known "Affected", every 3 months.   

WHAT RECORDS DOES THE BGV CLUB HOLD?  

From 2006, after members had sent in the results of their PBGVs' eye tests (with their consent) the BGV Club committee compiled a full record of all who had undergone eye testing.  For a small fee to cover printing and postage, this was made available in booklet form to club members, with the BGV Club retaining full copyright and a restriction on reproduction.  The aim of making the information available to members was to help breeders in their selection of sire and dam in an effort to control POAG in the breed.   In 2014-15 this method of maintaining a track on PBGV eye health was superseded by the advent of DNA testing and the official Kennel Club publication of results.  

DNA TESTING       

In the UK, the PBGV was originally the first breed certified for POAG under the Eye Scheme.  After many years' research, in 2014 the Animal Health Trust gave the exciting news that they had identified the genetic mutation responsible for POAG in PBGVs.  Since early 2015 a DNA test has been available. This test largely obviates the need for gonioscopy and will be invaluable in eradicating the disease from PBGVs as there is no predisposing factor that can be screened for by eye examination before the onset of the disease.   Following closure of the AHT and until the newly formed Canine Genetics section gets fully under way again, you can send cheek swabs to Animal DNA Diagnostics, having first paid for the test on-line or made an order by phone.   Animal DNA Diagnostics analyses these and sends a Letter of DNA Analysis, telling you whether your PBGV is Affected, a Carrier, or Clear of the disease.  They also send results to the Kennel Club.   

DNA TESTING RESULTS    

From early 2015 the AHT provided the BGV Club with regular updates on how many DNA tests by country had been carried out by them.  Naturally, over time, the number  decreased as most owners had come on board already.  The AHT also provided a list of those countries from which less than 5 samples had been received.  This was probably because the breed is numerically small in some countries.   ​Another factor in the diminishing number of DNA tests being carried out is that, armed with the knowledge of a PBGV's health status, breeders can now avoid a breeding that poses a risk.     ​The KC also publishes results of all PBGV DNA screening passed onto them by laboratories.  However this list is incomplete. The absence of published results on their website may be due to a number of reasons one of which is that, at the time of testing, the puppies had not been issued with full registration details so the DNA results could not be added to the database.    To help breeders when planning a litter, the BGV Club therefore provides a more complete list of DNA POAG testing results, which is updated regularly.
   
ANSWERING YOUR QUESTIONS ABOUT DNA TESTING      

DO ALL PBGVs NEED TESTING REGARDLESS OF AGE?   

YES!!!  Certainly all breeding stock should be tested. However, in the knowledge that a Clear to a Clear mating will produce all Clear puppies, consider which PBGVs need to be tested.  If you own several you may not need to have all of them tested as you may be spending money unnecessarily. Look at your pedigrees and start with the older hounds. In many cases this will entail liaison between breeders where one has used another's stud dog. If both sire and dam are tested Clear, off-spring from that mating will automatically be*Hereditary Clear, thus no need to test them. However, with the various possible permutations, any other than progeny from two Clear parents will require testing to establish their status. This is especially important with those destined for reproduction, as the key to managing genetic conditions with a DNA test through successive generations is in knowing exactly where the faulty copies of the genes are.   

*   ............ from the KC regarding DNA testing of Hereditary Clear Dogs. Pedigree error is a known phenomenon. DNA tests exist to ensure that no Affected puppies are born. The Hereditary Clear Status will therefore be limited to two Generations from January 2022

** i.e. great grand progeny (3rd generation) will need to be tested.   ** And an update from the KC dated 6 July 2021 - "Originally scheduled to come into effect in January 2022, this has now been postponed to 2023 to allow for necessary development work to be completed and in order for ‘hereditary clear’ status to be as effective and reliable as possible".   

IF A BREEDING BEWEEN TWO CLEARS BEARS NO RISK, WHAT ARE THE CONSEQUENCES OF OTHER MATINGS?  

For example, a Carrier can still be used for breeding purposes but the Carrier will need to be put to a Clear to avoid producing Affected offspring. The resultant litter from such a mating would produce on average 50% Carriers of the mutation. Although statistically two Carriers will produce Affected and Clear, this isn't guaranteed. Each dog carries one good and one faulty gene, so there is a chance that both sire and dam passed on their good gene.
 
As a breeder, even if you endorsed your puppies "Progeny not eligible for registration", based on known test results of the parents, if your litter is other than 100% clear, it will be your responsibility to contact those who bought a puppy from you, advising they get their PBGV's DNA analysed if they intend breeding - and making them alert to the possible consequences of reckless breeding.   

SO SHOULD WE BREED FROM CARRIERS?  

As part of her Animal Heath Trust work Cathryn Mellersh  produced a valuable and useful paper on the subject giving advice that Carriers should always be included in the first one or two generations that follow the launch of a DNA test for a recessive mutation.    This is regardless of the frequency of the mutation as it gives breeders the opportunity to capture desirable traits, such as breed type and temperament, before they start to select for dogs that are Clear of the mutation.    

WHAT IS THE DIFFERENCE BETWEEN ORDERING A SWAB TEST KIT AND ORDERING SWAB TESTING? 

When you order and pay on-line or by phone for a DNA test, you will be sent a swab test kit and instructions how to use it. At the time of ordering you will provide various details about your BGV including registered name, registration number, provisional name if not already registered, date of birth, sex and microchip number. ​ When you have a kit and have swabbed your BGV's mouth, you then send it off for testing and analysis.  

IS VETERINARY OR OTHER RESPONSIBLE CONTROL NEEDED WHEN SWABBING? 

Wiping round the inside of your BGV's mouth and cheeks is not difficult therefore it is not necessary to seek help from your vet, unless you want him/her to confirm that he/she has checked the microchip number during swabbing. 

DO I GAIN ANY BENEFIT FROM BEING AN ASSURED BREEDER?  

At the moment there are no discounts for Kennel Club Assured Breeders which can be applied for purchases at Animal (DNA) Diagnostics.   

DO ANY CONDITIONS APPLY FOR AN ASSURED BREEDER? 

As a Kennel Club ABS member,  you are obliged to DNA test your PBGVs.  This became effective from 20 July 2016.  It will not be necessary for those who breed from a Clear sire and Clear dam, as the offspring will be automatically clear (but see * above).

THE AHT (CANINE GENETICS) ALREADY HOLDS MY PBGV'S SWABS 

If a sample was used in the AHT's research and contributed towards finding the causal mutation for POAG in PBGVs, they would have reported their findings directly to the owner.  In the event, only a few cases were used to achieve this goal. PBGVs whose eyes were OK were not needed. While an increase in the intra-ocular pressures would indicate a case, an absence of this increased pressure didn't necessarily indicate an unaffected control - the PBGV could have been a carrier.   Submissions for DNA testing to any laboratory should ideally be traceable from when the order is placed through to providing the result. An exception to this is where a new sample is unobtainable because the dog has passed away since the research sample was submitted.  If you ever need information on a DNA test that was done some time ago, ask for a Letter of DNA Analysis and give a donation to help with the cost of analysis.        

HOW DO I FIND OUT THE STATUS OF A PBGV WHEN CONSIDERING A MATING OR BUYING A PUPPY?    

DNA test results are gradually fed through from the laboratory doing the test to the Kennel Club for publication. However bear in mind that the KC list of DNA test results is by no  means exhaustive, as some information may not have been available to them at the time, such as registration details.   You can search for a PBGV here, on the Kennel Club website    Alternatively, you can also view information on any PBGV's DNA status by using the BGV Club compiled Test Results here.     Another useful source of information can be found on the PBGV Club of America website which gives details of all PBGVs either registered with the AKC or shown in American PBGVs' pedigrees.  The information includes DNA test results.   

WILL I STILL NEED TO GET MY BGV's EYES TESTED?   

YES!!!  DNA testing is not an alternative to clinical testing but rather a tool to be utilised by breeders in conjunction with their normal selection criteria of conformation, temperament etc. Any dog or bitch intended for use in breeding should continue to be clinically screened on a regular basis. Certainly an eye examination before breeding is advisable in case there is a problem; and continued regular testing will highlight any problem.     

MOST IMPORTANTLY, even if you have obtained a DNA analysis, bear in mind that causes of glaucoma can be genetic or acquired, such as infections or trauma (known as secondary glaucoma).  Your PBGV may be predisposed to a combination of genetic mutation and a concurrent acquired eye disease.   In addition, with evidence that POAG can present in older dogs, eye testing into old age on an annual basis is therefore extremely desirable.   Great strides have been made in detecting the gene that causes the mutation leading to POAG and, while there is certainly no need for alarm, bear in mind that this is an evolving science and there may always be the exception that proves the rule.  If a problem is found early, there are remedies which may increase the length of time that your PBGV's eyesight remains good.   Eye testing should still take place, as there are other eye diseases that might be detected.  Picking them up early will help prevent it becoming an issue for the breed in the future  If you have any questions about DNA testing for POAG in PBGVs, contact Vivien Phillips, 01442 851225, vphillips@btinternet.com

Within the first year of DNA testing for POAG, over 1,050 PBGVs worldwide were tested by the Animal Health Trust.  

OTHER EYE PROBLEMS     

While POAG and cataracts remain the main problem in the breed, there is some minor evidence of diseases such as Persistent Pupillary Membranes (PPMs) and Lens Luxation.   For more details go to the Specific Concerns page.
CONTINUE TO CHECK EYES REGULARLY, IT MAY SAVE YOUR PBGV'S SIGHT!