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?
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.
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
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.
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
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:
UNAFFECTED EYE PRESSURES SATISFACTORY AT TIME OF EYE
EYE PRESSURES RAISED AT TIME OF EYE TESTING
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
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
(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
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.
RECORDS DOES THE BGV CLUB HOLD?
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.
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.
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.
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.
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
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.
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.
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
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
ALL PBGVs NEED TESTING REGARDLESS OF AGE?
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
** 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".
A BREEDING BEWEEN TWO CLEARS BEARS NO RISK, WHAT ARE THE CONSEQUENCES OF OTHER
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
SHOULD WE BREED FROM CARRIERS?
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.
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.
IS THE DIFFERENCE BETWEEN ORDERING A SWAB TEST KIT AND ORDERING SWAB
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.
you have a kit and have swabbed your BGV's mouth, you then send it off for
testing and analysis.
VETERINARY OR OTHER RESPONSIBLE CONTROL NEEDED WHEN SWABBING?
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
I GAIN ANY BENEFIT FROM BEING AN ASSURED BREEDER?
the moment there are no discounts for Kennel Club Assured Breeders
which can be applied for purchases at Animal (DNA)
ANY CONDITIONS APPLY FOR AN ASSURED BREEDER?
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).
AHT (CANINE GENETICS) ALREADY HOLDS MY PBGV'S SWABS
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.
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.
DO I FIND OUT THE STATUS OF A PBGV WHEN CONSIDERING A MATING OR BUYING A PUPPY?
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
can search for a PBGV here, on the Kennel Club website
you can also view information on any PBGV's DNA status by using the BGV Club
compiled Test Results here.
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
I STILL NEED TO GET MY BGV's EYES TESTED?
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.
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.
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,
Within the first year of DNA testing for POAG, over
1,050 PBGVs worldwide were tested by the Animal Health Trust.
OTHER EYE PROBLEMS
POAG and cataracts remain the main problem in the breed, there is some minor
evidence of diseases such as Persistent Pupillary Membranes (PPMs) and
more details go to the Specific Concerns page. CONTINUE TO CHECK EYES REGULARLY,
IT MAY SAVE YOUR PBGV'S SIGHT!
If you have any concerns about your BGV's well-being which appear to be related to any of the known health problems in the breed, let us know. We are here to support you.