During the last few years there has been an eye disease
discovered in many breeds. It is nothing new, the first case of PRA was
observed in England almost hundred years ago. We have tried to believe
it could not affect our lovely Lhasa Apsos. To be realistic, though, why
could it not happen to our breed when all the other Tibetan breeds are
affected with PRA ?
The first case was confirmed in Sweden
in the beginning of 1996. Since then, we have had a total of 33 cases of
PRA confirmed, 4 in Sweden, 12 in Norway, 2 in Denmark, 2 in Australia, 1 in the
Netherlands and 12 cases in England.
There are now (September 2000) approximately 1500 Lhasa Apsos tested for
this disease and 33 are proven affected with PRA. Because this is a recessive
gene, it means that as many as 330, or more than one fifth of those 1500 tested, may be dogs
carrying the defective gene! (The predicted carrier rate is about 10 times
as high as the affected rate).
There are also
4 Lhasa Apsos not counted in the above statistics. They are eye tested a
couple of times by one eye specialist as affected and also tested by
another specialist as unaffected! Before listing these four dogs we need a safe
identification (microchip/tattoo)
PROGRESSIVE RETINAL ATROPHY (
PRA ) is the medical
name of the disease. It means that the thin light sensing layer, the retina,
in the back of the eye slowly will die out. The dog has full sight at birth
and then slowly begins to lose cells of the retina. The unfortunate thing
about PRA is that it may not show up until the dog is around two and a
half to eight years of age. It always will end up in blindness.
The first signs can be seen when the dog doesn't want
to go out at night or when the dog is afraid of going into a dark room.
The dog has lost the night vision. When PRA progresses the dog can go upstairs
but seldom downstairs, it will jump up in the sofa or the bed and must
be helped down. When it has come this far it is important not to move any
objects in the dog's surroundings. The dog can still perceive moving objects
but will not see stationary things.
You can often see a green or orange shine reflecting out
of the dogs eyes. This is due to incoming light reflecting off the retina.
Normally we don't see this except in very dim light, because in most situations
the pupil is constricted. In PRA, the pupil will often be widely dilated
- the eye's vain attempt to let in moree light. Some dogs can be aggressive
when loosing sight but most of them will still be social. Even if your
Lhasa Apso has been blind it can live a normal life if you don't move the
dog from its normal surroundings. When loosing one sense the remaining
senses will be developed and more used.
This disease donīt follow what we call common sense
because the dogs develop their other senses to a level we never can imagine
and we are completely fooled into thinking a PRA dog still has a very good
sight.
The first case of PRA in Sweden was discovered when the
owner took the dog to the vet because they thought he had pain in the back
when he refused to go downstairs. The vet thought the dogs eyes seemed
to be a little bit strange so he was referred to an eye specialist the
same day. The dog was completely blind from PRA at 5 and a half years of
age. The owners of the dog told his breeder about the diagnosis, but they
were told to be quiet and not to discuss this with anybody. Two months
later the owners couldnīt keep this secret any longer and later on
this dog's parents were tested. The sire was also affected with PRA but
he could still see a little at seven years. His owner says he can move
freely in the forest and also see very small spiders moving on the wall
?? We met the father a year before he was tested and we thought he behaved
himself a little bit peculiarly.
Another dog, went to the vet for an eye infection and
she was also sent to an eye specialist. She was also completely blind with
PRA at nine years of age. All the other cases were discovered through
deliberate testing. In every case, the breeders were shocked because
they hadnīt noticed anything unusual about their dogs. They went
to the ophthalmologist believing their dogs could see very well, and totally
convinced that their dogs would be tested clear. Some of these other
cases were also totally blind!.
An eye specialist veterinarian can see if there is any
PRA in the eyes of your Lhasa Apso. Only dogs having PRA will test positive.
They have gotten a defective gene from both their parents. If your
dog is tested clear from the disease it can still be a carrier of the defective
gene and this gene has come from one of the parents.
If you plan to breed, it is necessary to test the stud
dog every year and the bitch each time before breeding them. The only thing we
can do to date is to examine our Lhasa Apsos and not to use proven carriers of
PRA in our breeding. In a couple of years we hope there will be a gene test
available where we also can identify the carriers. While we are waiting for this
method, every Lhasa Apso breeder and owner should examine for PRA and report the
test result to their local Lhasa Apso Club and of course to the breeder of the
tested dog. Breeders all over the world are working together to accumulate
information about PRA, because they need to know the dimensions of the PRA
problem in their respective breeding populations, and we need to encourage the
research toward a DNA test for the disease.
